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+I n t e r n a t i o n a l   T e l e c o m m u n i c a t i o n   U n i o n
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**X.1033**
+
+(04/2016)
+
+SERIES X: DATA NETWORKS, OPEN SYSTEM  
+COMMUNICATIONS AND SECURITY
+
+Information and network security – Network security
+
+# --- **Guidelines on security of individual information services provided by operators**
+
+Recommendation ITU-T X.1033
+
+## ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY
+
+|                                                        |                      |
+|--------------------------------------------------------|----------------------|
+| PUBLIC DATA NETWORKS                                   | X.1–X.199            |
+| OPEN SYSTEMS INTERCONNECTION                           | X.200–X.299          |
+| INTERWORKING BETWEEN NETWORKS                          | X.300–X.399          |
+| MESSAGE HANDLING SYSTEMS                               | X.400–X.499          |
+| DIRECTORY                                              | X.500–X.599          |
+| OSI NETWORKING AND SYSTEM ASPECTS                      | X.600–X.699          |
+| OSI MANAGEMENT                                         | X.700–X.799          |
+| SECURITY                                               | X.800–X.849          |
+| OSI APPLICATIONS                                       | X.850–X.899          |
+| OPEN DISTRIBUTED PROCESSING                            | X.900–X.999          |
+| INFORMATION AND NETWORK SECURITY                       |                      |
+| General security aspects                               | X.1000–X.1029        |
+| <b>Network security</b>                                | <b>X.1030–X.1049</b> |
+| Security management                                    | X.1050–X.1069        |
+| Telebiometrics                                         | X.1080–X.1099        |
+| SECURE APPLICATIONS AND SERVICES                       |                      |
+| Multicast security                                     | X.1100–X.1109        |
+| Home network security                                  | X.1110–X.1119        |
+| Mobile security                                        | X.1120–X.1139        |
+| Web security                                           | X.1140–X.1149        |
+| Security protocols                                     | X.1150–X.1159        |
+| Peer-to-peer security                                  | X.1160–X.1169        |
+| Networked ID security                                  | X.1170–X.1179        |
+| IPTV security                                          | X.1180–X.1199        |
+| CYBERSPACE SECURITY                                    |                      |
+| Cybersecurity                                          | X.1200–X.1229        |
+| Countering spam                                        | X.1230–X.1249        |
+| Identity management                                    | X.1250–X.1279        |
+| SECURE APPLICATIONS AND SERVICES                       |                      |
+| Emergency communications                               | X.1300–X.1309        |
+| Ubiquitous sensor network security                     | X.1310–X.1339        |
+| PKI related Recommendations                            | X.1340–X.1349        |
+| CYBERSECURITY INFORMATION EXCHANGE                     |                      |
+| Overview of cybersecurity                              | X.1500–X.1519        |
+| Vulnerability/state exchange                           | X.1520–X.1539        |
+| Event/incident/heuristics exchange                     | X.1540–X.1549        |
+| Exchange of policies                                   | X.1550–X.1559        |
+| Heuristics and information request                     | X.1560–X.1569        |
+| Identification and discovery                           | X.1570–X.1579        |
+| Assured exchange                                       | X.1580–X.1589        |
+| CLOUD COMPUTING SECURITY                               |                      |
+| Overview of cloud computing security                   | X.1600–X.1601        |
+| Cloud computing security design                        | X.1602–X.1639        |
+| Cloud computing security best practices and guidelines | X.1640–X.1659        |
+| Cloud computing security implementation                | X.1660–X.1679        |
+| Other cloud computing security                         | X.1680–X.1699        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T X.1033
+
+# Guidelines on security of individual information services provided by operators
+
+## Summary
+
+Recommendation ITU-T X.1033 addresses security aspects of the information services provided by telecommunication operators. In the transformation from providing traditional basic telecommunication services to providing comprehensive information services, operators have expanded their services to include content services and information and communication technology (ICT). These new services not only change the operational models but they also add new security issues to be resolved.
+
+This Recommendation provides guidelines on the security of the individual information services provided by telecommunication operators. The scope of this Recommendation covers the classification, security requirements, mechanisms and coordination of individual information services.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                   |
+|---------|----------------|------------|-------------|------------------------------------------------------------------------------|
+| 1.0     | ITU-T X.1033   | 2016-04-29 | 17          | <a href="http://handle.itu.int/11.1002/1000/11830-en">11.1002/1000/12849</a> |
+
+## Keywords
+
+Information service, security.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2016
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                          | <b>Page</b> |
+|--------------------------------------------------------------------------|-------------|
+| 1 Scope.....                                                             | 1           |
+| 2 References.....                                                        | 1           |
+| 3 Definitions .....                                                      | 1           |
+| 3.1 Terms defined elsewhere .....                                        | 1           |
+| 3.2 Terms defined in this Recommendation.....                            | 1           |
+| 4 Abbreviations and acronyms .....                                       | 2           |
+| 5 Conventions .....                                                      | 2           |
+| 6 Information services provided by telecommunication operators.....      | 2           |
+| 6.1 Communication services .....                                         | 3           |
+| 6.2 Content services.....                                                | 3           |
+| 6.3 Informationization service .....                                     | 4           |
+| 6.4 Individual information service .....                                 | 4           |
+| 6.5 Classification of roles .....                                        | 4           |
+| 7 Security objectives.....                                               | 5           |
+| 8 Security requirements .....                                            | 5           |
+| 8.1 Security requirements of traditional telecommunication services..... | 5           |
+| 8.2 Security requirements of content services .....                      | 7           |
+| 8.3 Security requirements of informationization services .....           | 8           |
+| 8.4 Security coordination.....                                           | 9           |
+| 9 Security mechanism.....                                                | 9           |
+| Bibliography.....                                                        | 12          |
+
+
+
+## Recommendation ITU-T X.1033
+
+# Guidelines on security of individual information services provided by operators
+
+# 1 Scope
+
+This Recommendation provides guidelines on the security of individual information services provided by telecommunication operators. It describes the classification of the individual information services provided by telecommunication operators as well as security objectives, requirements, mechanisms and coordination of individual information services.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+None.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 bearer service** [b-ITU-T I.112]: A type of telecommunication service that provides the capability for the transmission of signals between user-network interfaces.
+
+**3.1.2 teleservice** [b-ITU-T I.112]: A type of telecommunication service that provides the complete capability, including terminal equipment functions, for communication between users according to protocols established by agreement between Administrations and/or recognized operating agencies (ROAs).
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 basic telecommunication service**: A bearer service or teleservice. The terms "bearer service" and "teleservice" are defined in clauses 3.1.1 and 3.1.2, respectively.
+
+**3.2.2 individual information service**: This is the service process of content searching, indexing, information collection, filtering, ordering and provision of content to specific user(s) or to user groups based on information obtained of users' requirements, privileges, preferences and habitual behaviours, etc.
+
+**3.2.3 informationization service**: A service that offers solutions to encountered issues or a service that provides assessment, prediction and prevention of possible problems by using information technology and other high-tech means.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                                          |
+|------|------------------------------------------|
+| CRM  | Customer Resource Management             |
+| ICP  | Internet Content Provider                |
+| ICT  | Information and Communication Technology |
+| IPTV | Internet Protocol TeleVision             |
+| ISP  | Internet Service Provider                |
+| IT   | Information Technology                   |
+| OA   | Office Automation                        |
+| QoS  | Quality of Service                       |
+| ROA  | Recognized Operating Agency              |
+| SMS  | Short Message Service                    |
+| TV   | Television                               |
+
+# 5 Conventions
+
+None.
+
+# 6 Information services provided by telecommunication operators
+
+Information services provided by telecommunication operators include voice services, data services and information services such as online information providing and data indexing via public networks, e.g., fixed networks, mobile networks, Internet and other telecommunication infrastructures. The informationization service provided to other organizations by operators is also included. To provide information services, telecommunication operators and/or other third parties must collect, analyse and process information and construct a platform to help users to access, share and exchange the information.
+
+Information services provided by telecommunication operators can be classified into three categories (as shown in Figure 1):
+
+- Communication service;
+- Content service; and
+- Informationization service.
+
+![Venn diagram showing the composition of information services provided by telecommunication operators. Three overlapping circles represent 'Communication service', 'Content service', and 'Informationization service'.](731f533b0599c8e42a063f06e4332045_img.jpg)
+
+A Venn diagram consisting of three overlapping circles. The top circle is labeled 'Communication service'. The bottom-left circle is labeled 'Content service'. The bottom-right circle is labeled 'Informationization service'. The circles overlap in the center and at the intersections between pairs of circles. The circles are light blue with a thin black outline.
+
+Venn diagram showing the composition of information services provided by telecommunication operators. Three overlapping circles represent 'Communication service', 'Content service', and 'Informationization service'.
+
+X.1033(16)\_F01
+
+**Figure 1 – Composition of information services provided by telecommunication operators**
+
+## **6.1 Communication services**
+
+Traditionally, telecommunication operators provide communication services with their network infrastructures including fixed networks, mobile networks, Internet, satellite, etc. These services include voice, video, data and multimedia. Typical communication services include:
+
+- Telephone services;
+- Internet broadband service;
+- Mobile services;
+- Directory service;
+- Telegraph service;
+- Telematic service;
+- Message handling service;
+- Videophone.
+
+## **6.2 Content services**
+
+Content services are the extension of communication services. These kinds of services may be provided by operators as well as by third parties, such as Internet service providers (ISPs) and Internet content providers (ICPs). Typical content services include:
+
+- Access portal;
+- Web indexing/searching;
+- Application store;
+- Mobile reading/advertising/newspaper;
+- Mobile television (TV)/Internet protocol television (IPTV);
+- Location service/mobile navigation;
+- Social networking.
+
+Usually, in order to address the application and content services area, operators need to design and develop applications and produce content themselves or simply collect contents from other companies that produce music, television programmes, or financial services such as credit cards, stock trading, etc.
+
+In the transformation from providing traditional basic telecommunication services to providing comprehensive information services, the operators expand their services to include content services and information and communication technology (ICT). Consequently their business value chain changes to include these new businesses, as shown in Figure 2 below.
+
+![Figure 2 – Content service chain diagram showing Traditional value chain, New value chain, Application value chain, and Content value chain.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg)
+
+The diagram illustrates the Content service chain, divided into four main value chains:
+
+- Traditional value chain:** A sequence of four grey chevron-shaped boxes pointing right: "Access service", "Terminal device", "Network device", and "Network operation".
+- New value chain:** A sequence of three chevron-shaped boxes pointing right: "Middleware" (grey), "Application" (yellow), and "Content" (red).
+- Application value chain:** A sequence of four yellow chevron-shaped boxes pointing right: "Requirement analysis", "Application design", "Application practice", and "Application-operation".
+- Content value chain:** A sequence of four red chevron-shaped boxes pointing right: "Content making", "Content management", "Content providing", and "Portal".
+
+Dashed lines indicate relationships and data flow between the chains:
+
+- A dashed line connects the "Application" box in the New value chain to the "Requirement analysis" box in the Application value chain.
+- A dashed line connects the "Application" box in the New value chain to the "Application practice" box in the Application value chain.
+- A dashed line connects the "Application" box in the New value chain to the "Content making" box in the Content value chain.
+- A dashed line connects the "Content" box in the New value chain to the "Content providing" box in the Content value chain.
+- A dashed line connects the "Content" box in the New value chain to the "Portal" box in the Content value chain.
+
+X.1033(16)\_F02
+
+Figure 2 – Content service chain diagram showing Traditional value chain, New value chain, Application value chain, and Content value chain.
+
+**Figure 2 – Content service chain**
+
+## 6.3 Informationization service
+
+Informationization is the goal of an information society. The informationization service is the service that offers solutions to encountered issues or the service that provides assessment, prediction and prevention of possible problems by using information technology and other high-technical means.
+
+Currently operators enter this area with their advantages in information technology (IT) knowledge and network infrastructure. They provide solutions for encountered issues, or provide assessment, prediction and prevention of possible problems, such as consulting, training and information outsourcing, etc. Typical informationization services include:
+
+- E-government (for governments);
+- E-commerce, mobile office automation (OA) (for enterprises);
+- Digital live, digital entertainment (for homes);
+- E-health, e-education (for persons).
+
+## 6.4 Individual information service
+
+Individual information service is the service process of content searching, indexing, information collection, filtering, ordering and provision of content to specific user(s) or user groups based on the information obtained of users' requirements, privileges, preferences and habitual behaviours, etc.
+
+In this process, the users' requirements, privileges, preferences and habitual behaviours, etc., are (under the user's authorization) perceived by individual information service providers and are used for content searching, indexing, information collection, filtering, sorting and processing, etc. The searching and collecting of user-preferred content information should abide by the users' privileges, while the method, the process and the extent of information provided should comply with the users' preferences and habitual behaviours. The information should be provided to users with user-preferred security and quality of service.
+
+## 6.5 Classification of roles
+
+As mentioned, stakeholders involved in the information services provided by telecommunication operators can be classified, based on their roles, into regulators, operators, third-party service providers and end users. Under this classification of roles, different stakeholders each have their own security requirements:
+
+- Regulators. Based on service regulations and legislations, regulators need to put forward security requirements for operators and service providers to ensure service availability, fair competition and privacy protection, etc.
+
+- Operators. Operators need security measures to safeguard their infrastructures, service operation and business interests. Operators have obligations to fulfil their duties towards their users and the public at national and international level.
+- Service providers. Third-party service providers need to enforce security measures to ensure their services are delivered to end users through operators' networks and to protect their own business information from leaking to malicious users.
+- End users/subscribers. When accepting the offered services, the end users/subscribers should ensure data confidentiality (ensure privacy protection as well as service availability).
+
+# **7 Security objectives**
+
+Security objectives are the ultimate security goal for providing information services from telecommunication operators. Here the primary concerns are in which security requirements should be met rather than on how security is enforced. The security objectives for the information services provided by telecommunication operators are:
+
+- Only legitimate users should be able to access the information services provided by the telecommunication operators; on the other hand, users should use the service legitimately and abide by service requirements.
+- Operators or third-party service providers should provide privacy protection for subscribers and service users.
+- In order to ensure service availability and business continuity, operators should provide protection against unsolicited access and ensure a secure delivery of services.
+- Manageability and controllability should be provided to the extent that upon encountering security incidents, either normal state can be restored or damage can be minimized.
+- The security measures should not compromise essential quality of service; they should be considered comprehensively including performance, service availability, upgrading and costs.
+- Only authorized operators, service providers and users may have access to their prescribed scope of security-related information.
+
+# **8 Security requirements**
+
+Security requirements aim to meet security objectives. They should address the following issues:
+
+- Confidentiality (confidentiality of stored and transferred information);
+- Data integrity (protection of stored and transferred information);
+- System integrity (protection of the operating platform);
+- Accountability (all actions should be documented and should be accounted for by their initiators);
+- Availability (all legitimate users should be able to correctly access the services); and
+- Recoverability and manageability (any security violations should be handled to ensure that the system or the services can be restored to their normal state).
+
+## **8.1 Security requirements of traditional telecommunication services**
+
+As people's needs change and services evolve, new features and functions are added to traditional telecommunication services. This transformation brings new security issues as well as new security technologies to mitigate them. For example, as the traditional telephone directory service expands to personal and enterprise switchboards, operators are further required to protect the privacy of their users. In order to improve service convenience and quality of service (QoS), etc., new identity
+
+recognition and authentication technologies (such as voice recognition via the phone, etc.) might be used. This example shows that even for the traditional telecommunication services, the expansion and transformation of services brings new security issues as well as new security technologies to mitigate them. Figure 3 shows a schematic model of telecommunication services provision.
+
+![Figure 3: Schematic model of telecommunication services provision. The diagram shows a central box labeled 'Operator's infrastructure' containing two sub-boxes: 'Access control platform' and 'Service providing platform'. Two ovals labeled 'User' are positioned on either side. Arrows indicate interactions: from the left 'User' to both platforms, from both platforms to the right 'User', and a downward arrow from the 'Access control platform' to the 'Service providing platform'.](007b053fe94a8348f75128a584503fd0_img.jpg)
+
+```
+
+graph LR
+    subgraph Infrastructure [Operator's infrastructure]
+        ACP[Access control platform]
+        SPP[Service providing platform]
+        ACP --> SPP
+    end
+    U1((User)) --> ACP
+    U1 --> SPP
+    ACP --> U2((User))
+    SPP --> U2
+
+```
+
+X.1033(16)\_F03
+
+Figure 3: Schematic model of telecommunication services provision. The diagram shows a central box labeled 'Operator's infrastructure' containing two sub-boxes: 'Access control platform' and 'Service providing platform'. Two ovals labeled 'User' are positioned on either side. Arrows indicate interactions: from the left 'User' to both platforms, from both platforms to the right 'User', and a downward arrow from the 'Access control platform' to the 'Service providing platform'.
+
+**Figure 3 – Schematic model of telecommunication services provision**
+
+Under the classification of roles described in clause 6.5, these roles respectively bring forward security requirements for traditional telecommunication services as listed below.
+
+#### 8.1.1 Security requirements given by regulators
+
+Security requirements of traditional telecommunication services given by regulators include:
+
+- Recommend and/or supervise the enforcement of regulations based on the hierarchical importance of the traditional telecommunication services. Recommend and/or supervise the enforcement of security ratings and risk assessment to services and underlying infrastructures.
+- The following capabilities should be provided: network security monitoring, network security incident announcement and emergency security coordination.
+- Establish the rules to promote fair business competition between operators.
+- Set the rules to prevent users from utilizing the traditional telecommunication services for illegal purposes.
+
+#### 8.1.2 Security requirements for operators
+
+Security requirements of traditional telecommunication services for operators include:
+
+- Maintain the infrastructures operating securely and steadily.
+- Provide adequate authentication to prevent illegal users from accessing the services.
+- Provide measures to prevent users from utilizing the services illegally.
+- Ensure service availability and protect the services from malicious attacks.
+- Ensure the capability of emergency recovery from disasters, attacks and other unexpected service breakdowns.
+- Provide protection against unintended information leakage or intentional attacks.
+
+#### 8.1.3 Security requirements given by users
+
+Security requirements of traditional telecommunication services given by users include:
+
+- Have access to pre-authorized services without obstacles.
+- User privacy information is protected from unintended leakage or intentional attacks.
+
+## 8.2 Security requirements of content services
+
+Content services provided by telecommunication operators are mainly related to the new types of/extended services that originate from the Internet, broadcasting and television, etc. These new types of/extended services include e-commerce, Internet searching, on-demand video and digital television terrestrial broadcasting, etc. that are transmitted via the telecommunication infrastructures. These new types of services/extended services relate to technologies including malicious/detrimental information reports, identity authentication, customer resource management (CRM) and access control, etc., and are also accompanied by new forms/types of security threats and associated new security requirements. Figure 4 shows a schematic model of third-party content service provision.
+
+![Figure 4: Schematic model of third-party content service provision. The diagram shows the flow of information from collection to processing to releasing, then through an access control platform and service providing platform to a user, all within the context of operator/service provider and operator's infrastructure.](eefe19c5e14dc4d6c316b7f7fbb7d7d7_img.jpg)
+
+```
+graph LR; subgraph "Information platform of operator/service provider"; IC[Information collection] --> IP[Information processing]; IP --> IR[Information releasing]; end; subgraph "Operator's infrastructure"; AC[Access control platform] --> SP[Service providing platform]; end; IR --> SP; AC <--> User((User)); SP <--> User;
+```
+
+The diagram illustrates the schematic model of third-party content service provision. It is divided into two main sections: the 'Information platform of operator/service provider' and the 'Operator's infrastructure'. The 'Information platform' contains three sequential steps: 'Information collection', 'Information processing', and 'Information releasing'. The 'Operator's infrastructure' contains two components: 'Access control platform' and 'Service providing platform'. The 'Information releasing' step from the first platform connects to the 'Service providing platform' in the second. The 'Access control platform' and 'Service providing platform' both have bidirectional connections with the 'User' (represented by an oval). The label 'X.1033(16)\_F04' is located at the bottom right of the diagram.
+
+Figure 4: Schematic model of third-party content service provision. The diagram shows the flow of information from collection to processing to releasing, then through an access control platform and service providing platform to a user, all within the context of operator/service provider and operator's infrastructure.
+
+**Figure 4 – Schematic model of third-party content service provision**
+
+#### 8.2.1 Security requirements for regulators
+
+Security requirements of content services for regulators include:
+
+- Establish the rules to maintain fair business competition for operators and third-party service providers.
+- Set the rules for service providers (operators and third-party service providers) to avoid publishing harmful content or services.
+- Require providers (operators and third-party service providers) to provide the capability to control, when necessary, the spread of harmful content and/or other harmful behaviour utilizing the content services.
+
+#### 8.2.2 Security requirements for operators
+
+Security requirements of content services for operators include:
+
+- Maintain service availability, especially real-time service operational consistency.
+- Ensure that service users are authorized.
+- Ensure that users' operations are pre-authorized.
+- Ensure that the outsourced third-party content services provided via the operator's systems and networks are authorized, controllable and clean from fake/illegal contents.
+- Protect the services from malicious attacks (especially phishing attacks on personal data and properties).
+- Have the ability to properly handle service interruptions, provide quick recovery and keep service operational consistency.
+- Prevent information leakage either unintentionally or by attackers stealing the information.
+
+#### 8.2.3 Security requirements for third-party service providers
+
+Security requirements of content services for third-party service providers include:
+
+- Ensure that the provided content is delivered to clients correctly and ensure that the normal interactions between service providers and users are conducted according to the established norms.
+- Protect information integrity and protect information from being tampered with or lost.
+- Protect provided content from being illegally stolen or leaked.
+
+#### **8.2.4 Security requirements given by users**
+
+Security requirements of content services given by users include:
+
+- Service availability and privacy are ensured.
+- Stable service performance (especially for paid services) is provided.
+- Personal information especially bank cards, passwords, home addresses and phone numbers are protected from unauthorized access or leakage.
+- In cases of unexpected service breakdown, personal data can be recovered and restored and personal information leakage is prevented.
+
+### **8.3 Security requirements of informationization services**
+
+If the operator provides an enterprise with informationization services such as an e-mail system, a telephone directory, data storage, an office automation system, intranet, information technology (IT) planning and consulting, etc., then the informationization service is, as a result, involved in the business processes of the enterprise as well as trade secrets and technical know-how of its customer(s). For this reason, the informationization services must be provided with security protection.
+
+#### **8.3.1 Security requirements for regulators**
+
+Security requirements of informationization services for regulators include:
+
+- Set the rules to protect key information confidentiality, such as business information, technical information and so on.
+- Establish the rules to maintain fair business competition among the different operators.
+
+#### **8.3.2 Security requirements for operators**
+
+Security requirements of informationization services for operators include:
+
+- Maintain service availability to keep normal work or business activities.
+- Ensure that the service users are authorised users; and ensure that the authorized users' operations are pre-authorised.
+- Protect the services especially those of the financial sector from malicious attacks.
+- Have the ability to properly handle service interruption; provide quick recovery and maintain service operational consistency.
+- Prevent information leakage either unintentionally or by an attacker stealing the information.
+
+#### **8.3.3 Security requirements given by users**
+
+Security requirements of informationization services given by users include:
+
+- Ensure service availability. Ensure that work or business processes run efficiently and continue to do so as expected.
+- Ensure confidentiality. Maintain key information confidentiality such as geolocation, business information and technical information.
+- Ensure service stability. Ensure that work or business processes are not disrupted by service breakdown in key process activities, especially for group users.
+
+- Ensure instant service recovery based on the backup system especially for real-time services.
+- Protect key information from unauthorized access or leakage.
+
+### **8.4 Security coordination**
+
+The individual user is the basic unit of an individual information service. A group user consists of a number of basic units. Therefore, the security of an individual user information service should be harmonized with that of the group user information service; and the security policies applied for individual users and those applied for group users should be coordinated. The following mechanisms need to be considered:
+
+- The security policies for individual users should be based on the security policies for the group users to which they belong. This means that the individual users should implement the security policies for the group users to which they belong. For example, individual employees are usually required to install the anti-virus software and update the software patches provided by their employing company.
+- When the specific security requirements of an individual user are in conflict with the group security policies, a revision of the current situation has to be carried out in order to reach a new security resolution. In addition, all these activities have to be documented.
+- When an individual of a group is attacked or has vulnerabilities, the group security administrator needs to be informed. The existing security measures should be adjusted and/or the new security measures should be implemented based on the whole group user environment.
+- When a security exception occurs on an individual of a group, the individual needs first be isolated from the group network environment. He or she can then re-access the group network after security assessment and enforcement.
+- The security policies should be stored and applied preferably on the server group or on the border of the group network, so that personal terminal loads can be reduced.
+
+# **9 Security mechanism**
+
+In order to reduce the operational costs and enhance competitiveness, operators shall consider various service requirements and security issues comprehensively. For example, operators currently are trying to develop application recognition and user recognition technology; in other words, they are trying to capture the user's preferences and push more applications and services to the user. In this case, the operators have to find a balance between the ability to serve their customers and the protection of their privacy.
+
+The existing security technologies of network and information systems are mainly applied to devices, networks and services to meet security requirements such as access control, confidentiality, availability, data integrity and authentication. From the viewpoint of the information service, the main concern is the users. All users are different and ideally, they should be served differently/individually. The security elements such as encryption, identity authentication, logs, information filtering and privacy protection, should be regrouped and tailored to be a part of the information service. It is necessary to reconsider the mechanisms in accordance with the concrete devices, networks and services.
+
+Table 1 gives some related security mechanisms for the different types of individual information services.
+
+**Table 1 – Related security mechanisms for the different types of individual information services**
+
+| <b>Security mechanism category</b> | <b>Security mechanism</b>                                                                                                                                                                                                       | <b>Traditional telecommunication service</b>                   | <b>Content service</b>                                                           | <b>Informationization service</b>                                                                             |
+|------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------|----------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------|
+| Rules and regulations              | Set the rules to promote fair business competition                                                                                                                                                                              | √                                                              | √                                                                                | √                                                                                                             |
+|                                    | Security rating and risk assessment                                                                                                                                                                                             | √                                                              | √                                                                                | √                                                                                                             |
+| Data and system backup             | History data backup for network crime tracing and digital evidence                                                                                                                                                              | User access related information                                | User behaviour such as financial transactions                                    |                                                                                                               |
+|                                    | Backup system (including network device, servers and data) for service recovery                                                                                                                                                 | √                                                              | √                                                                                | √                                                                                                             |
+| Identity management                | Identity authentication including password, digital certificate, short message service (SMS) verification code, biometrics identification (voice recognition, facial recognition, iris recognition, fingerprint identification) | Password, biometrics identification (mainly voice recognition) | Password, digital certificate, short message service (SMS) verification code     | Password, biometrics identification (mainly facial recognition, iris recognition, fingerprint identification) |
+|                                    | Role-based access control                                                                                                                                                                                                       | √                                                              | √                                                                                | √                                                                                                             |
+| Data security management           | Data encryption, including database encryption, and transferred data encryption                                                                                                                                                 | Identity information encryption                                | Identity information encryption, service related personal information encryption | Mainly encryption on business information, technical information and government information                   |
+|                                    | Data integrity check                                                                                                                                                                                                            | √                                                              | √                                                                                | √                                                                                                             |
+| Malicious attack prevention        | Enterprise version of anti-virus software or anti-spam software                                                                                                                                                                 |                                                                |                                                                                  | √                                                                                                             |
+|                                    | Terminal monitoring and control for group users                                                                                                                                                                                 |                                                                |                                                                                  | √                                                                                                             |
+|                                    | Client anti-virus software                                                                                                                                                                                                      | √                                                              | √                                                                                | √                                                                                                             |
+|                                    | Server-based intrusion detection system                                                                                                                                                                                         | √                                                              | √                                                                                | √                                                                                                             |
+|                                    | Risk assessment and safety reinforcement                                                                                                                                                                                        | √                                                              | √                                                                                | √                                                                                                             |
+
+**Table 1 – Related security mechanisms for the different types  
+of individual information services**
+
+| <b>Security<br/>mechanism<br/>category</b> | <b>Security mechanism</b>                                     | <b>Traditional<br/>telecommunication<br/>service</b> | <b>Content<br/>service</b> | <b>Informationization<br/>service</b> |
+|--------------------------------------------|---------------------------------------------------------------|------------------------------------------------------|----------------------------|---------------------------------------|
+|                                            | Operator network based<br>firewall and anti-virus<br>software | √                                                    | √                          |                                       |
+
+## Bibliography
+
+- [b-ITU-T I.112] Recommendation ITU-T I.112 (1993), *Vocabulary of terms for ISDNs*.
+- [b-ITU-T Q.956.3] Recommendation ITU-T Q.956.3 (1995), *Integrated services digital network (ISDN) – Stage 3 description for charging supplementary services using DSS 1: Clause 3 – Reverse charging*.
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | General tariff principles                                                                                                                                 |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| Series F        | Non-telephone telecommunication services                                                                                                                  |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Terminals and subjective and objective assessment methods                                                                                                 |
+| Series Q        | Switching and signalling                                                                                                                                  |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| <b>Series X</b> | <b>Data networks, open system communications and security</b>                                                                                             |
+| Series Y        | Global information infrastructure, Internet protocol aspects and next-generation networks, Internet of Things and smart cities                            |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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+
+
+I n t e r n a t i o n a l   T e l e c o m m u n i c a t i o n   U n i o n
+
+# ITU-T
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+# X.1043
+
+(03/2019)
+
+SERIES X: DATA NETWORKS, OPEN SYSTEM  
+COMMUNICATIONS AND SECURITY
+
+Information and network security – Network security
+
+# --- **Security framework and requirements for service function chaining based on software- defined networking**
+
+Recommendation ITU-T X.1043
+
+## ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY
+
+|                                                        |                      |
+|--------------------------------------------------------|----------------------|
+| PUBLIC DATA NETWORKS                                   | X.1–X.199            |
+| OPEN SYSTEMS INTERCONNECTION                           | X.200–X.299          |
+| INTERWORKING BETWEEN NETWORKS                          | X.300–X.399          |
+| MESSAGE HANDLING SYSTEMS                               | X.400–X.499          |
+| DIRECTORY                                              | X.500–X.599          |
+| OSI NETWORKING AND SYSTEM ASPECTS                      | X.600–X.699          |
+| OSI MANAGEMENT                                         | X.700–X.799          |
+| SECURITY                                               | X.800–X.849          |
+| OSI APPLICATIONS                                       | X.850–X.899          |
+| OPEN DISTRIBUTED PROCESSING                            | X.900–X.999          |
+| INFORMATION AND NETWORK SECURITY                       |                      |
+| General security aspects                               | X.1000–X.1029        |
+| <b>Network security</b>                                | <b>X.1030–X.1049</b> |
+| Security management                                    | X.1050–X.1069        |
+| Telebiometrics                                         | X.1080–X.1099        |
+| SECURE APPLICATIONS AND SERVICES (1)                   |                      |
+| Multicast security                                     | X.1100–X.1109        |
+| Home network security                                  | X.1110–X.1119        |
+| Mobile security                                        | X.1120–X.1139        |
+| Web security                                           | X.1140–X.1149        |
+| Security protocols (1)                                 | X.1150–X.1159        |
+| Peer-to-peer security                                  | X.1160–X.1169        |
+| Networked ID security                                  | X.1170–X.1179        |
+| IPTV security                                          | X.1180–X.1199        |
+| CYBERSPACE SECURITY                                    |                      |
+| Cybersecurity                                          | X.1200–X.1229        |
+| Countering spam                                        | X.1230–X.1249        |
+| Identity management                                    | X.1250–X.1279        |
+| SECURE APPLICATIONS AND SERVICES (2)                   |                      |
+| Emergency communications                               | X.1300–X.1309        |
+| Ubiquitous sensor network security                     | X.1310–X.1319        |
+| Smart grid security                                    | X.1330–X.1339        |
+| Certified mail                                         | X.1340–X.1349        |
+| Internet of things (IoT) security                      | X.1360–X.1369        |
+| Intelligent transportation system (ITS) security       | X.1370–X.1389        |
+| Distributed ledger technology security                 | X.1400–X.1429        |
+| Distributed ledger technology security                 | X.1430–X.1449        |
+| Security protocols (2)                                 | X.1450–X.1459        |
+| CYBERSECURITY INFORMATION EXCHANGE                     |                      |
+| Overview of cybersecurity                              | X.1500–X.1519        |
+| Vulnerability/state exchange                           | X.1520–X.1539        |
+| Event/incident/heuristics exchange                     | X.1540–X.1549        |
+| Exchange of policies                                   | X.1550–X.1559        |
+| Heuristics and information request                     | X.1560–X.1569        |
+| Identification and discovery                           | X.1570–X.1579        |
+| Assured exchange                                       | X.1580–X.1589        |
+| CLOUD COMPUTING SECURITY                               |                      |
+| Overview of cloud computing security                   | X.1600–X.1601        |
+| Cloud computing security design                        | X.1602–X.1639        |
+| Cloud computing security best practices and guidelines | X.1640–X.1659        |
+| Cloud computing security implementation                | X.1660–X.1679        |
+| Other cloud computing security                         | X.1680–X.1699        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T X.1043
+
+# Security framework and requirements for service function chaining based on software-defined networking
+
+## Summary
+
+Recommendation ITU-T X.1043 analyses security threats to and specifies security requirements for service function chaining based on software-defined networking (SDN). The corresponding security countermeasures are also given. Recommendation ITU-T X.1043 also aims to help understanding of security risks encountered when using SDN-based service function chaining and implementation of secured SDN-based service function chains.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T X.1043   | 2019-03-16 | 17          | <a href="http://handle.itu.int/11.1002/1000/13872">11.1002/1000/13872</a> |
+
+## Keywords
+
+SDN, service function chain, SFC, software-defined networking.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2019
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|    |                                                                                                                  | Page |
+|----|------------------------------------------------------------------------------------------------------------------|------|
+| 1  | Scope.....                                                                                                       | 1    |
+| 2  | References.....                                                                                                  | 1    |
+| 3  | Definitions .....                                                                                                | 1    |
+|    | 3.1 Terms defined elsewhere.....                                                                                 | 1    |
+|    | 3.2 Terms defined in this Recommendation.....                                                                    | 2    |
+| 4  | Abbreviations and acronyms .....                                                                                 | 3    |
+| 5  | Conventions .....                                                                                                | 3    |
+| 6  | Overview.....                                                                                                    | 4    |
+| 7  | General security framework of software-defined networking-based service<br>function chaining .....               | 6    |
+| 8  | Threat analysis and requirements of critical network elements.....                                               | 7    |
+|    | 8.1 Critical network elements.....                                                                               | 7    |
+|    | 8.2 Security threats and requirements .....                                                                      | 7    |
+| 9  | Threat analysis and requirements of interfaces .....                                                             | 12   |
+|    | 9.1 Interfaces .....                                                                                             | 12   |
+|    | 9.2 Security threats and requirements .....                                                                      | 12   |
+| 10 | Security considerations of policy management .....                                                               | 12   |
+| 11 | Countermeasures.....                                                                                             | 12   |
+|    | 11.1 Countermeasures for critical network elements .....                                                         | 13   |
+|    | 11.2 Countermeasures for interface security .....                                                                | 14   |
+|    | 11.3 Countermeasures for secure policy management .....                                                          | 14   |
+|    | Annex A – Classification table and service function path forwarding table .....                                  | 15   |
+|    | A.1 Classification table .....                                                                                   | 15   |
+|    | A.2 Service function path forwarding table .....                                                                 | 17   |
+|    | Appendix I – Service function chain architecture specified by other standards<br>development organizations ..... | 18   |
+|    | Bibliography.....                                                                                                | 20   |
+
+# **Introduction**
+
+Service function chaining enables administrators to distribute network policies more efficiently and conveniently, while software-defined networking (SDN) helps to adjust traffic dynamically according to changing requirements. These two technologies can be combined to give a network higher flexibility and stronger capability to support on-demand services.
+
+However, it is clear that SDN-based service function chaining also introduces new security challenges to the network, not only legacy threats associated with SDN, but also new threats associated with the service function chain (SFC).
+
+Use of SDN architecture means that common networking threats will show up in SDN-based service function chaining, e.g., more severe denial of service/distributed denial of service (DoS/DDoS) attacks caused by a centralized SDN controller and attacks on the application-control interface.
+
+More security issues arise because of the deployment of service function chaining. New network elements are introduced, like an SFC forwarder, and new information is transferred among network elements, like SFC classification rules and service function path (SFP) forwarding rules. Threats against these entities should be mitigated. Thus there is an urgent need for the security guidelines in this Recommendation.
+
+## Recommendation ITU-T X.1043
+
+# Security framework and requirements for service function chaining based on software-defined networking
+
+# 1 Scope
+
+This Recommendation analyses security threats encountered in service function chaining based on software-defined networking (SDN) and specifies security guidelines for SDN-based service function chaining architectures. This Recommendation:
+
+- describes a general security architecture for SDN-based service function chaining;
+- analyses security threats to and requirements of network elements and corresponding interfaces in the SDN-based service function chaining architecture;
+- describes and analyses policy management problems in SDN-based service function chaining;
+- suggests countermeasure solutions to meet these requirements.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [ITU-T X.800] Recommendation ITU-T X.800 (1991), *Security architecture for Open Systems Interconnection for CCITT applications*.
+- [ITU-T X.1038] Recommendation ITU-T X.1038 (2016), *Security requirements and reference architecture for software-defined networking*.
+- [ITU-T Y.3300] Recommendation ITU-T Y.3300 (2014), *Framework of software-defined networking*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 classification** [b-IETF RFC 7665]: Locally instantiated matching of traffic flows against policy for subsequent application of the required set of network service functions. The policy may be customer/network/ service specific.
+
+**3.1.2 classifier** [b-IETF RFC 7665]: An element that performs classification.
+
+**3.1.3 metadata** [b-IETF RFC 7665]: Provides the ability to exchange context information between classifiers and SFs, and among SFs.
+
+**3.1.4 service function (SF)** [b-IETF RFC 7665]: A function that is responsible for specific treatment of received packets. A service function can act at various layers of a protocol stack (e.g., at the network layer or other OSI layers). As a logical component, a service function can be realized as a virtual element or be embedded in a physical network element. One or more service functions can
+
+be embedded in the same network element. Multiple occurrences of the service function can exist in the same administrative domain.
+
+**3.1.5 service function chain (SFC)** [b-IETF RFC 7665]: A service function chain defines an ordered set of abstract service functions and ordering constraints that must be applied to packets and/or frames and/or flows selected as a result of classification.
+
+**3.1.6 service function forwarder (SFF)** [b-IETF RFC 7665]: A service function forwarder is responsible for forwarding traffic to one or more connected service functions according to information carried in the SFC encapsulation, as well as handling traffic coming back from the SF. Additionally, an SFF is responsible for delivering traffic to a classifier when needed and supported, transporting traffic to another SFF (in the same or different type of overlay), and terminating the service function path (SFP).
+
+**3.1.7 service function path (SFP)** [b-IETF RFC 7665]: The service function path is a constrained specification of where packets assigned to a certain service function path must go. While it may be so constrained as to identify the exact locations, it can also be less specific. The SFP provides a level of indirection between the fully abstract notion of service chain as a sequence of abstract service functions to be delivered, and the fully specified notion of exactly which SFF/SFs the packet will visit when it actually traverses the network. By allowing the control components to specify this level of indirection, the operator may control the degree of SFF/SF selection authority that is delegated to the network.
+
+**3.1.8 SFC-enabled domain** [b-IETF RFC 7665]: A network or region of a network that implements SFC. An SFC-enabled domain is limited to a single network administrative domain.
+
+**3.1.9 SFC encapsulation** [b-IETF RFC 7665]: The SFC encapsulation provides, at a minimum, SFP identification, and is used by the SFC-aware functions, such as the SFF and SFC-aware SFs. The SFC encapsulation is not used for network packet forwarding. In addition to SFP identification, the SFC encapsulation carries metadata including data-plane context information.
+
+**3.1.10 SFC proxy** [b-IETF RFC 7665]: Removes and inserts SFC encapsulation on behalf of an SFC-unaware service function. SFC proxies are logical elements.
+
+## **3.2 Terms defined in this Recommendation**
+
+This Recommendation defines the following terms:
+
+**3.2.1 service function chain classification rule:** A rule generated and maintained by a service function chain (SFC) controller and classifier, respectively. It reflects the policies for binding an incoming flow to a given SFC and service function path (SFP). An SFC classification rule can be translated into an SFC flow rule by the software-defined networking (SDN) controller and formed into an entry in an SFC classification table, like an SDN flow entry in an SDN flow table.
+
+**3.2.2 service function chain controller:** A function in a software-defined networking (SDN) controller that instructs the functional elements on the service function chain (SFC) resource layer to process packets within an SFC-enabled domain. After receiving the SFC requirements from the applications (apps), the SFC controller translates the requirements into the SFC classification rules and service function path (SFP) forwarding rules and sends them to the classifiers and the service function forwarders (SFFs), respectively, via the SDN controller.
+
+**3.2.3 service function chain flow rule:** A flow rule on the classifiers and the service function forwarders (SFFs) that are translated by the software-defined networking (SDN) controller from the service function chain (SFC) classification rule and the service function path (SFP) forwarding rule.
+
+**3.2.4 service function path forwarding rule:** A rule generated and maintained by a service function chain (SFC) controller and a service function forwarder (SFF), respectively. It reflects the policies for forwarding an incoming flow to a given service function (SF). A service function path (SFP) forwarding rule can be translated into an SFC flow rule by the software-defined networking
+
+(SDN) controller and formed into an entry in an SFP) forwarding rule table like an SDN flow entry in an SDN flow table.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|       |                                        |
+|-------|----------------------------------------|
+| ACL   | Access Control List                    |
+| AES   | Advanced Encryption Standard           |
+| app   | application                            |
+| DDoS  | Distributed Denial of Service          |
+| DoS   | Denial of Service                      |
+| HMAC  | Hash-based Message Authentication Code |
+| HTTPS | Hypertext Transfer Protocol Secure     |
+| IP    | Internet Protocol                      |
+| IPS   | Intrusion Prevention System            |
+| IPSec | Internet Protocol Security             |
+| LSP   | Label-Switched Path                    |
+| MPLS  | Multi-Protocol Label Switching         |
+| NBI   | Northbound Interface                   |
+| NSH   | Network Service Header                 |
+| OSI   | Open Systems Interconnection           |
+| PSK   | Pre-Shared Key                         |
+| RBAC  | Role-Based Access Control              |
+| SDN   | Software-Defined Networking            |
+| SF    | Service Function                       |
+| SFC   | Service Function Chain                 |
+| SFF   | Service Function Forwarder             |
+| SFP   | Service Function Path                  |
+| SI    | Service Index                          |
+| SPI   | Service Path Identifier                |
+| TLS   | Transport Layer Security               |
+| TTL   | Time To Live                           |
+| VNF   | Virtualized Network Function           |
+
+# 5 Conventions
+
+In this Recommendation:
+
+The keywords "**is required to**" indicate a requirement that must be strictly followed and from which no deviation is permitted, if conformance to this Recommendation is to be claimed.
+
+The keywords "**is recommended**" indicate a requirement that is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+
+The keywords "**is prohibited from**" indicate a requirement that must be strictly followed and from which no deviation is permitted, if conformance to this Recommendation is to be claimed.
+
+The keywords "**can optionally**" indicate an optional requirement that is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option, and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+# 6 Overview
+
+The high-level architecture of SDN is specified in [ITU-T Y.3300]. It includes three layers: application layer, control layer and resource layer. The SDN control layer provides a means to dynamically and deterministically control the behaviour of network resources (e.g., data transport and processing), as instructed by the application layer. The features of the SDN (i.e., decoupled control function and transportation function, centralized control layer) are suitable for the implementation of service function chaining: the SDN control layer can program the service function chaining policy from the application layer and control the resource layer to forward packages/flows according to such policy.
+
+Based on the high-level architecture of SDN, Figure 6-1 shows a general reference architecture of an SDN-based service function chaining as a basis for security analysis.
+
+![Figure 6-1: General reference architecture of software-defined networking-based service function chaining. The diagram shows three main layers: SFC application layer, SFC control layer, and SFC resource layer. The SFC application layer contains multiple APP boxes. The SFC control layer contains an SFC controller and an SFC enabler (SDN controller). The SFC resource layer shows three options for deploying classifiers and SFFs: Option 1 (Switch Classifier, Switch, SFF), Option 2 (Classifier, SFF, Switch, Switch), and Option 3 (Classifier, SFF, Switch Classifier, Switch, SFF). These options connect to an SF pool containing SF and SFC proxy components.](daa4a6fa7e2ba1954258f86b4928eb32_img.jpg)
+
+The diagram illustrates the general reference architecture of software-defined networking-based service function chaining, organized into three main layers:
+
+- SFC application layer:** Contains multiple application (APP) boxes.
+- SFC control layer:** Contains the SFC controller and the SFC enabler (SDN controller).
+- SFC resource layer:** Contains three options for deploying classifiers and service function forwarders (SFFs):
+  - Option 1:** A switch containing a classifier, a switch, and an SFF.
+  - Option 2:** A classifier, an SFF, a switch, and another switch.
+  - Option 3:** A classifier, an SFF, a switch containing a classifier, a switch, and an SFF.
+
+These options connect to an **SF pool** at the bottom, which contains service function (SF) and SFC proxy components.
+
+Figure 6-1: General reference architecture of software-defined networking-based service function chaining. The diagram shows three main layers: SFC application layer, SFC control layer, and SFC resource layer. The SFC application layer contains multiple APP boxes. The SFC control layer contains an SFC controller and an SFC enabler (SDN controller). The SFC resource layer shows three options for deploying classifiers and SFFs: Option 1 (Switch Classifier, Switch, SFF), Option 2 (Classifier, SFF, Switch, Switch), and Option 3 (Classifier, SFF, Switch Classifier, Switch, SFF). These options connect to an SF pool containing SF and SFC proxy components.
+
+X.1043(19)\_F6-1
+
+**Figure 6-1 – General reference architecture of software-defined networking-based service function chaining**
+
+In Figure 6-1, the definitions of classifier, service function forwarder (SFF), service function (SF) and SFC proxy are those of [b-IETF RFC 7665]. There are three options to deploy the classifier and SFF on the SFC resource layer: 1) classifier and SFF are embedded into switches; 2) classifier and SFF are deployed in independent devices; 3) the implementation of classifier and SFF includes the combination of options 1) and 2). As for these three options, a classification table and an SFP table
+
+based on the OpenFlow flow table specified in [b-ONF TS-025] are defined in this Recommendation in order to reflect SFC rules, i.e., the classification rule and SFP forwarding rule. The detailed formats of the classification table and the SFP table are specified in Annex A.
+
+The SFC control function (referred to as an SFC controller in this Recommendation) can be implemented as an application of an SDN controller or as a logical function embedded in an SDN controller. This means that the interface between the SFC controller and the SDN controller can be either an application-control interface or a private interface, depending on the implementation.
+
+The SFC enabler in the SDN controller is responsible for: 1) receiving and responding to the request for network information from the SFC controller in order to create valid SFCs; and 2) receiving classification and SFP forwarding rules (i.e., the flow entry of the classification table and SFP table) from the SFC controller and combining them with OpenFlow rules for distribution to the SFC resource layer.
+
+The components and functions of each layer are as follows.
+
+- SFC application layer: This layer refers to the application layer in the SDN architecture of [ITU-T Y.3300] where apps can send user SFC requirements to the SFC controller to customize the behaviour of user flows. The apps can also request SFC information from the SFC controller.
+- SFC control layer: This layer is like the control layer in the SDN architecture [ITU-T Y.3300], except that the SFC controller is included.
+  - The SFC controller is responsible for programming SFC classification rules and SFP forwarding rules according to SFC policies received from apps. Before transporting the SFC classification rules and the SFP forwarding rules to the SDN controller, the SFC controller checks whether these new SFC classification rules and SFP forwarding rules conflict with the stored active SFC classification rules and SFP forwarding rules in the SFC repository of the SFC controller.
+  - When the SFC controller is implemented as an application of the SDN controller, the SFC enabler in the SDN controller receives SFC rules from the SFC controller, combines them with the OpenFlow flow rules and sends the combined rules to related entities in the SFC resource layer. The detailed processes are as follows.
+    - The SFC enabler in the SDN controller combines the SFC classification rules and SFP forwarding rules with OpenFlow flow rules after receiving them from the SFC controller. The SDN controller programs the combined rules of the classifiers, SFFs and switches, respectively, and then forwards packages/flows according to SFC classification rules, SFP forwarding rules and OpenFlow flow rules. In order to support SFC classification rules and SFP forwarding rules, the classification table and the SFP table specified in Annex A are required.
+    - The SDN controller processes and coordinates the policy conflict between the translated flow rules from the SFC classification rules and SFP forwarding rules and the stored SDN flow rules.
+    - The SDN controller sends these translated flow rules to the related classifiers, SFFs and switches, respectively.
+- SFC resource layer: This layer includes switches, classifiers, SFFs, SFC proxies and SFs.
+  - The classifiers and the SFFs process the flows according to the flow rules. The classifier classifies the flows and adds the SFC encapsulation (e.g., the network service header (NSH) [b-IETF RFC 8300]) into the packet that is transmitted to the SFFs, SFs, etc. The classifier sends the flows to the SFF after adding the SFC encapsulation. The SFF transports the flows to SFs/SFC proxies or the next SFFs after receiving the flows from classifiers/other SFFs or SFs/SFC proxies, respectively, according to SFP forwarding
+
+rules. The classifier and SFF can be implemented on the switches. In this case, the classifier and SFF need to be registered in the SFC controller, and the switches that support classifier/SFF functions need to be indicated to the SDN controller that programs the flow forwarding path.
+
+- The SFC-aware SFs are responsible for processing the received flows and also need to register in the SFC controller and provide their status to the SFC controller by the interfaces between the SFC controller and the SFs or through the management element. The SF can be a virtualized network function (VNF) or a physical device.
+- The SFC proxies are responsible for removing and inserting SFC encapsulation on behalf of any SFC-unaware service functions. They can also inform the SFC controller of SF status by the interface between the SFC controller and the SFs or through the management element. SFC proxies are logical elements.
+
+According to Figure 6-1, the following interfaces are included.
+
+- SFC application-control interface: The interface between the application layer and the control layer. The interface between the SFC controller and the SDN controller can also be an application-control interface or a private interface. This interface is mainly used to transmit policies (e.g., SFC policy, classification rule).
+- SFC resource-control interface: The interface between the control layer and the resource layer, e.g., the interface between the SDN controller and the SFF. This interface is mainly used to transmit flow rules.
+- SFC intra-interfaces in the resource layer: This includes the interface between the classifier and the SFF, the interface between the SFF and the SF, the interface between the SFF and the SFC proxy, and the SFC proxy and the SF. This interface is mainly used to transmit data flows.
+- Management interface between the SFC controller and the SF/SFC proxy: The SFs/SFC proxies use this interface to register the SFs in the SFC controller and to send SF status. The SFC controller requests SF status and configures the SFs with this interface. This interface can be implemented by a direct interface between the SFC controller and SF/SFC proxy or an indirect interface through a management element between the SFC controller and SF/SFC proxy. Because there can be many implementations for this interface, it is not described in Figure 6-1.
+
+# **7 General security framework of software-defined networking-based service function chaining**
+
+The security reference architecture for SDN is specified in [ITU-T X.1038] and can be applied to SDN-based service function chaining, with the addition of some specific security features. A general security architecture of SDN-based service function chaining is shown in the next paragraph, but only emphasizes security specific to the SDN-based service function chaining.
+
+Three security feature groups are defined in Figure 7-1.
+
+(I) Critical network elements security: A set of security features that provides security functions on network entities to support secure creation, running, maintenance and deletion of an SFC.
+
+(II) Interface security: A set of security features that provides security functions to ensure secure transportation of communication data.
+
+(III) Policy management: A set of security features that provides policy lifecycle security, e.g., the policy is created by a legal SFC application (app), sent with security protection and implemented correctly. It also resolves the SFC policy conflict, e.g., the conflict between the new SFC classification rules and the stored active SFC classification rules in the SFC repository of the SFC
+
+controller, the conflict between the translated flow rules from the SFC classification rules and the traditional SDN flow rules on the SDN controller.
+
+![Figure 7-1: General security framework of software-defined networking-based service function chaining. The diagram shows a three-layer architecture. The top layer (Application Layer) contains an 'APP' box. The middle layer (Control Layer) contains an 'SFC controller' box and an 'SFC enabler' box, which is nested within an 'SDN controller' box. The bottom layer (Resource Layer) contains a 'Classifier' box, two 'SFF' (Service Function Forwarder) boxes, and three 'SF' (Service Function) boxes: 'SFC-aware SF', 'SFC proxy', and 'SFC-unaware SF'. Arrows indicate interactions: (I) red arrows from APP to SFC controller and from SFC controller to SFC enabler; (II) green double-headed arrows between APP and SFC controller, between SFC controller and SFC enabler, between SFC enabler and the Classifier/SFF/SF layer, and between the Classifier and the first SFF; (III) blue dashed arrows from APP to SFC controller, from SFC controller to SDN controller, and from SDN controller to the SFF/SF layer. The SFF boxes are interconnected with each other and with the SF boxes.](4e4be0bd8b235167902f2c03e41da651_img.jpg)
+
+X.1043(19)\_F7-1
+
+Figure 7-1: General security framework of software-defined networking-based service function chaining. The diagram shows a three-layer architecture. The top layer (Application Layer) contains an 'APP' box. The middle layer (Control Layer) contains an 'SFC controller' box and an 'SFC enabler' box, which is nested within an 'SDN controller' box. The bottom layer (Resource Layer) contains a 'Classifier' box, two 'SFF' (Service Function Forwarder) boxes, and three 'SF' (Service Function) boxes: 'SFC-aware SF', 'SFC proxy', and 'SFC-unaware SF'. Arrows indicate interactions: (I) red arrows from APP to SFC controller and from SFC controller to SFC enabler; (II) green double-headed arrows between APP and SFC controller, between SFC controller and SFC enabler, between SFC enabler and the Classifier/SFF/SF layer, and between the Classifier and the first SFF; (III) blue dashed arrows from APP to SFC controller, from SFC controller to SDN controller, and from SDN controller to the SFF/SF layer. The SFF boxes are interconnected with each other and with the SF boxes.
+
+**Figure 7-1 – General security framework of software-defined networking-based service function chaining**
+
+# 8 Threat analysis and requirements of critical network elements
+
+## 8.1 Critical network elements
+
+For SDN-based service function chaining, the critical network elements include:
+
+- SFC application layer: app;
+- SFC control layer: SDN controller, SFC controller;
+- SFC resource layer: classifier, SFF, SF, SFC proxy, switch.
+
+The security threats and requirements of the app, SDN controller and switch are described in [ITU-T X.1038].
+
+## 8.2 Security threats and requirements
+
+In this Recommendation, the SFC is SDN based, thus the security threats and security requirements of [ITU-T X.1038] apply. Clauses 8.2.1 to 8.2.5 focus only on the specific security threats and security requirements of SDN-based SFCs.
+
+#### 8.2.1 Security threats to and requirements of service function chain controller
+
+##### 8.2.1.1 Security threats
+
+The SFC controller is an important component that programs SFC classification and SFP forwarding rules. It has the following security threats.
+
+- **Service function chain classification rule/service function path forwarding rule conflict:** An SFC classification rule and an SFP forwarding rule can conflict with other SFC classification rules and SFP forwarding rules, respectively, stored on the SFC controller. An attacker may use the SFC classification rule conflict and the SFP forwarding rule conflict to bypass security controls.
+
+- **Fake service function chain classification rule/service function path forwarding rule insertion:** An attacker can use a malicious app to send an SFC requirement to an SFC controller. This may cause the SFC controller to program an SFC classification rule or SFP forwarding rule to steer a flow that bypasses some SFs; thus the flow cannot be processed correctly.
+- **Untrusted software-defined networking controller:** A fake SDN controller can receive SFC classification rules/SFP forwarding rules from an SFC controller, when the SFC controller is implemented as an app on the SDN controller, and can result in sensitive data leakage. When the SFC controller is implemented as a function in the SDN controller, it can also be attacked when the controller is attacked.
+- **Spoofing:** An attacker can pose as a legal app or an administrator to communicate with the SFC controller to launch attacks. For example, the spoofing app can send a user SFC requirement and cause a new SFC classification rule and a new SFP forwarding rule to be installed. These rules can change the path of the flows and cause further attacks.
+- **Repudiation:** The administrators of the SFC controller can repudiate behaviours, such as SFC classification rule tampering.
+- **Information disclosure:** An attacker can access sensitive data on the SFC controller (e.g., SFC classification rules, SFP forwarding rules, administrator password), which can result in other attacks. For example, an attacker utilizes a leaked administrator password on the SFC controller to tamper with the SFC classification rule to cause further attacks.
+- **Fake service function status:** An attacker can send a fake SF status to the SFC controller, which can lead to an incorrect SFC classification rule/SFP forwarding rule being programmed by the SFC controller.
+- **Security vulnerability on the service function chain controller:** An attacker can access the SFC controller by exploiting security vulnerabilities on the SFC controller (e.g., code flaw) to compromise the SFC controller and the SDN controller.
+- **Denial of service attack:** An attacker can utilize a large number of apps to send SFC requirements to the SFC controller at the same time. Then, the SFC controller translates these SFC requirements into SFC classification rules and SFP forwarding rules, which may cause an overload on the SFC controller. The SFs/SFC proxies can also launch a DoS attack on the SFC controller. For example, a large number of SFs can send a fake SF status to cause the SFC controller to change the SFC classification rule and SFP forwarding rule continually until the SFC controller is overloaded.
+
+##### 8.2.1.2 Security requirements
+
+R-01: The SFC controller is recommended to support policy conflict to prevent bypassing important policies (e.g., security policy, management policy).
+
+R-02: The SFC controller is required to authenticate the app.
+
+R-03: The SFC controller is required to authenticate the administrator.
+
+R-04: The SFC controller is required to authenticate the SDN controller.
+
+R-05: The SFC controller is required to authenticate the SF/SFC proxy.
+
+R-06: The SFC controller is required to authenticate the management.
+
+R-07: The SDN controller is required to satisfy the requirements of clause 7.2.2 of [ITU-T X.1038].
+
+R-08: The SFC controller is required to support log and audit function.
+
+R-09: The SFC controller is required to authorize apps to provide SFC requirements or request SFC information.
+
+- R-10: The SFC controller is required to authorize the administrator to manage the SFC controller.
+- R-11: The SFC controller is required to verify the integrity of the status of the SF and authenticate the identity of the sender if SF status is transmitted by the management element.
+- R-12: The SFC controller is recommended to protect the confidentiality and integrity [ITU-T X.800] of stored sensitive data, e.g., SFC classification rules, SFP forwarding rules, SFC category and available SFs.
+- R-13: The SFC controller is recommended to provide the key/certificate management function to support authentication/authorization and data protection.
+- R-14: The SFC controller is recommended to support vulnerability detection and patch functions to mitigate security threats from the SFC controller software.
+- R-15: The SFC is recommended to provide mechanisms for anti-DoS, e.g., limiting requests from the classifiers/SFFs or SFC apps.
+
+#### 8.2.2 Security threats to and requirements of a classifier
+
+##### 8.2.2.1 Security threats
+
+Major specific security threats to the classifier are as follows.
+
+- **Spoofing:** An attacker can pose as a legal SDN controller to communicate with the classifier to try to launch spoofing attacks. For example, the spoofed SDN controller can make a fake FSC flow rule, thus causing an incorrect classification.
+- **Repudiation:** The administrators on the classifier can repudiate their behaviours, such as SFC flow rule tampering.
+- **Information disclosure:** An attacker can access sensitive data on the classifier. For example, an attacker can access SFC flow rules to acquire all flow classifications, and then the attacker can derive the SFC topology.
+- **Untrusted service function chain controller:** A fake SFC controller can send malicious SFC classification rules to the SDN controller to cause classification errors on the classifier. Further attacks may also be launched.
+- **Security vulnerability on the classifier:** An attacker can try to exploit a security vulnerability on the physical host or virtual host that runs the classifier application to escalate its privileges and launch further attacks, e.g., SFC flow rule tampering.
+- **Denial of service attack:** An attacker can send a large number of flows to the classifier, for flow classifications at the same time, and cause an overload on the classifier.
+- **Service function chain flow rule overflow:** An SDN controller, under malicious conditions, can be induced to send a large number of SFC flow rules to the classifier (e.g., the SDN controller is compromised by an attacker or the algorithm on the SDN controller is designed unreasonably.). These flow rules are translated by the classifier and applied as entries in an SDN flow table. Because an SDN flow table has finite resources to store these entries, receiving a great number of SFC flow rules can cause an overflow of entries in the SFC flow table on the classifier.
+
+##### 8.2.2.2 Security requirements
+
+- R-16: The classifier is required to authenticate the SDN controller.
+- R-17: The classifier is required to authenticate the administrator.
+- R-18: The classifier is required to authenticate the SFF.
+- R-19: The classifier is required to support log and audit functions.
+- R-20: The classifier is required to authorize access to sensitive data.
+
+R-21: The classifier is required to protect the security of stored sensitive data, e.g., SFC flow rules, SFC encapsulation.
+
+R-22: The classifier is recommended to provide key/certificate management functions to support authentication/authorization and data protection.
+
+R-23: The physical host or virtual machine, which runs the classifier, is recommended to support the mechanism to detect and mitigate security vulnerabilities. Provision of hardening for the classifier software is required.
+
+R-24: The classifier is recommended to support the mechanism to detect abnormal flows and mitigate overloads.
+
+R-25: The classifier is recommended to set an appropriate expiration time for the SFC flow rules and to support a mechanism to detect maliciously sent SFC flow rules.
+
+R-26: The SDN controller is required to authenticate and authorize the SFC controller. This requirement is the same as R-12 and R-13 of [ITU-T X.1038].
+
+#### 8.2.3 Security threats to and requirements of the service function forwarder
+
+##### 8.2.3.1 Security threats
+
+Major specific security threats to the SFF are described as follows.
+
+- **Spoofing:** An attacker can pose as a legitimate SDN controller, classifier, other SFF or SFs, to communicate with the SFF to try to launch spoofing attacks. For example, a spoofed SDN controller can create a fake flow rule to cause a false flow forward.
+- **Untrusted service function chain controller:** A fake SFC controller can send malicious SFP forwarding rules to the SDN controller to cause a flow forwarding path error. Further attacks may also be launched.
+- **Repudiation:** The administrators on the SFF can repudiate behaviours, such as SFC flow rule tampering.
+- **Information disclosure:** An attacker can access sensitive data on the SFF (e.g., the SFC rule, administrator password) and cause other attacks. For example, an attacker can utilize the leaked administrator password to log on to the SFF and tamper with SFC flow rules.
+- **Security vulnerability on the service function forwarder:** An attacker can try to exploit security vulnerabilities on the SFF and then escalate their privileges to further compromise the SFF.
+- **Denial of service attack:** An attacker can send a large number of flows to the SFF at the same time and cause an overload on the SFF.
+- **Service function chain rule overflow:** An SDN controller, under malicious conditions, can send a large number of SFC flow rules to the SFF (e.g., the SDN controller is compromised by an attacker or the algorithm on the SDN controller is designed unreasonably). These flow rules are translated from the SFP forwarding rules and applied as entries in an SDN flow table. Because an SDN flow table has finite resources to store these entries, receiving a great number of SFC flow rules can cause an overflow of entries in the SFC flow table on the SFF.
+
+##### 8.2.3.2 Security requirements
+
+R-27: The SFF is required to authenticate the SDN controller.
+
+R-28: The SFF is required to authenticate the administrator.
+
+R-29: The SFF is required to authenticate the classifier.
+
+R-30: The SFF is required to authenticate the SFs/SFC proxies.
+
+R-31: The SFF is required to support the log function and audit function.
+
+R-32: The SFF is required to authorize access to sensitive data, e.g., the SFC flow rules.
+
+R-33: The SFF is recommended to protect the security of sensitive data stored on the SFF.
+
+R-34: The SFF is recommended to provide key/certificate management functions to support authentication/authorization and data protection.
+
+R-35: The SFF is recommended to support mechanisms to detect and mitigate security vulnerabilities.
+
+R-36: The SFF is recommended to support mechanisms to detect abnormal flows and mitigate overloads.
+
+R-37: The SFF is recommended to set an appropriate expiration time for SFC flow rules and support a mechanism to detect maliciously sent SFC flow rules.
+
+R-38: The SDN controller is required to authenticate and authorize the SFC controller. This requirement is in the same as R-12 and R-13 of [ITU-T X.1038].
+
+#### **8.2.4 Security threats to and requirements of a service function**
+
+##### **8.2.4.1 Security threats**
+
+An SF has the following major security threats.
+
+- **Spoofing:** An attacker can pose as a legitimate SFC controller/SFF to communicate with the SF to try to launch attacks. For example, a spoofed SFC controller can request SF location/status to launch further attacks.
+- **Repudiation:** The administrators on the SF can repudiate their behaviours, e.g., SF configuration modification.
+- **Information disclosure:** An unauthorized attacker can access sensitive data on the SF, e.g., administrator passwords and configuration policies.
+- **Security vulnerability on the service function:** An attacker can try to exploit security vulnerabilities on the physical host or virtual host that runs the SF application to escalate its privileges and launch further attacks, e.g., tampering with SF configuration and management policies.
+- **Denial of service attack:** An attacker can send a large number of the flows to the SF at the same time and cause an overload on the SF.
+
+##### **8.2.4.2 Security requirements**
+
+R-39: The SF is required to authenticate the SFC controller.
+
+R-40: The SF is required to authenticate the administrator.
+
+R-41: The SF is required to authenticate the SFF.
+
+R-42: The SF is required to authenticate the SFC proxy.
+
+R-43: The SF is required to authenticate the management element.
+
+R-44: The SF is required to support the log and audit function.
+
+R-45: The SF is required to authorize access to sensitive data, e.g., SF configuration and management policies and parameters.
+
+R-46: The SF is required to protect the security of stored sensitive data.
+
+R-47: The SF is required to provide key/certificate management functions to support authentication/authorization and data protection.
+
+R-48: The SF is recommended to support mechanisms to detect and mitigate security vulnerabilities.
+
+R-49: The SF is recommended to support mechanisms to detect abnormal flows and mitigate overloads.
+
+#### **8.2.5 Security threats to and requirements of a service function chain proxy**
+
+##### **8.2.5.1 Security threats**
+
+Since the SFC proxy acts as an SFF when it communicates with an SFC-unaware SF and acts as an SF when it communicates with an SFF, the security threats to the SFF and the SF apply to the SFC proxy; therefore, for the security threats to the SFC proxy, see clause 8.2.3.1 and clause 8.2.4.1.
+
+##### **8.2.5.2 Security requirements**
+
+For the security requirements of the SFC proxy, refer to clause 8.2.3.2 and clause 8.2.4.2.
+
+# **9 Threat analysis and requirements of interfaces**
+
+## **9.1 Interfaces**
+
+According to the general reference architecture of SDN-based service function chaining in Figure 6-1, there are the following interfaces:
+
+- application-control interface;
+- resource-control interface;
+- intra-interfaces in the resource layer;
+- management interface between the SFC controller and the SF/SFC proxy.
+
+## **9.2 Security threats and requirements**
+
+#### **9.2.1 Security threats**
+
+These interfaces are threatened by common security threats to an interface, i.e., an attacker can eavesdrop, tamper and replay flows that are sent or received by the interfaces.
+
+### **9.2.2 Security requirements**
+
+These interfaces are required to support the following common security requirements for an interface.
+
+R-50: Mutual authentication between entities on the interfaces.
+
+R-51: The flows that are transformed or received by these interfaces are required to support confidentiality, integrity [ITU-T X.800] and anti-replay protection.
+
+# **10 Security considerations of policy management**
+
+A policy determines the forwarding behaviour of flows in an SDN-based service function chaining. There are two types of policy: the SFC policy and the traditional SDN flow policy. These policies are transformed into flow rules. For example, SFC policies are transformed into SFC classification rules and SFP forwarding rules by the SFC controller; the SDN controller then transforms the received SFC classification rules and SFP forwarding rules into the flow rules.
+
+The security threat to the policy management then is that an attacker can fake a policy, which can result in a conflict between the new flow rules and the stored rules. Thus, security requirements for the policy management involve resolving conflict between flow rules.
+
+# **11 Countermeasures**
+
+This clause recommends countermeasures to meet security requirements corresponding to those in clause 8.2 and clause 9.2. Some security mechanisms refer to the security mechanisms in
+
+[ITU-T X.1038]. These countermeasures can guide the design and implementation of security functions when developing SDN-based service function chaining.
+
+## 11.1 Countermeasures for critical network elements
+
+A list of recommended countermeasures to meet security requirements corresponding to those in clause 8 and clause 9 follows.
+
+- Resolving policy conflict: To meet the requirement of R-01, first, the SFC controller needs to authenticate and authorize the SFC app to ensure the policy comes from a trusted app. Then, the SFC controller can use a mechanism similar to that in clause B.1 of [ITU-T X.1038] to set priorities for all policies.
+- Authentication: Username/password-based authentication, authentication based on a pre-shared key (PSK) ([b-IETF RFC 4279], [b-IETF RFC 4306]) and certificate-based authentication ([b-IETF RFC 4306], [b-IETF RFC 5246] etc.) can be used to meet the authentication requirements, especially for security requirements R-02, R-03, R-04, R-05, R-06, R-16, R-17, R-18, R-26, R-27, R-28, R-29, R-30, R-38, R-39, R-40, R-41, R-42 and R-43. An appropriate countermeasure should be selected according to the deployment environment.
+- Secure SDN controller: The SDN controller security mechanisms proposed in clause 8.2 of [ITU-T X.1038] can be used. These mechanisms are especially used to meet requirement R-07.
+- Log and audit: The OS log function can be used and log server employed to store the security logs, operation logs etc. Logs can be used to audit. These mechanisms can meet log and audit requirements, especially for security requirements R-08, R-19, R-31 and R-44.
+- Authorization: Access control list (ACL), role-based access control (RBAC) etc. can be used to meet authorization requirements, especially for security requirements R-09, R-10, R-20, R-26, R-32, R-38 and R-45.
+- Data integrity: A hash-based message authentication code (HMAC) [b-IETF RFC 2104] or digital signature etc. can be used to protect data, e.g., SF status to meet the data integrity requirements, especially for security requirements R-11, R-12, R-21, R-33 and R-46.
+- Confidentiality: The advanced encryption standard (AES) can be used to meet confidentiality protection requirements, especially R-12, R-21, R-33 and R-46.
+- Key/certificate management: The key management mechanism specified in [ITU-T X.800] and certificate management protocol defined in [b-IETF RFC 4210] can be applied. The requirements of R-13, R-22, R-34 and R-47 can be satisfied.
+- Vulnerability detection and patch functions: Security tools to detect and patch these vulnerabilities can be used. This mechanism especially meets requirements R-14, R-23, R-35 and R-48.
+- Anti-DoS: Limiting the number of requests, authenticating the requester, deploying anti-DoS devices etc. can be used together. This mechanism especially meets requirement R-15.
+- Detection of abnormal flow and flow overload: An intrusion prevention system (IPS) can be deployed to detect abnormal flow. Protected entities can support the setting of a threshold value to limit processing flows. These mechanisms especially meet requirements R-24, R-36 and R-49.
+- Protection of SFC flow rule against overflow: The protected entity (e.g., classifier, SFF) needs to authenticate the SDN controller, set an appropriate expiration time for the SFC flow rule and a threshold value for receiving the SFC flow rule. These mechanisms especially meet requirements R-25 and R-37.
+
+## 11.2 Countermeasures for interface security
+
+A list of recommended countermeasures to meet corresponding security requirements for interfaces follows.
+
+- Mutual authentication on the interfaces: PSK-based authentication ([b-IETF RFC 4279], [b-IETF RFC 4306]), and certificate-based authentication ([b-IETF RFC 4306], [b-IETF RFC 5246] etc.) can be used by parties to authenticate each other on the interfaces. This mechanism meets requirement R-50.
+- Confidentiality, integrity and anti-replay protection on the interfaces that meet requirement R-51.
+- Application-control interface: Like the recommended countermeasures in clause 8.4 of [ITU-T X.1038], it is recommended that transport layer security (TLS) [b-IETF RFC 5246] or hypertext transfer protocol secure (HTTPS) protocols be implemented and deployed in the SFC application and the SFC controller, or SFC application and SDN controller to provide mutual authentication between the SFC application and the SFC controller, or between SFC application and SDN controller, as well as to provide data confidentiality, data integrity and anti-replay for data transportation over the application-control interface.
+- Resource-control interface: Like the recommended countermeasures in clause 8.4 of [ITU-T X.1038], it is recommended that TLS [b-IETF RFC 5246] or Internet protocol security (IPSec) protocols ([b-IETF RFC 4301], [b-IETF RFC 4303], [b-IETF RFC 4835]) be implemented and deployed in the SDN controller and classifier/SFF/switch to provide mutual authentication between the SDN controller and classifier/SFF/switch, as well as to provide data confidentiality, data integrity and anti-replay for data transportation over the resource-control interface.
+- Intra-interfaces in the resource layer: It is recommended that IPSec protocols ([b-IETF RFC 4301], [b-IETF RFC 4303], [b-IETF RFC 4835]) be implemented and deployed in the intra-interfaces, e.g., between classifier and SFF, SFF and SF/SFC proxy, to provide mutual authentication between the entities on the intra-interface, as well as providing data confidentiality, data integrity and anti-replay for data transportation over the intra-interface.
+- Management interface between the SFC controller and the SF/SFC proxy: It is recommended that TLS [b-IETF RFC 5246] or IPSec protocols ([b-IETF RFC 4301], [b-IETF RFC 4303], [b-IETF RFC 4835]) be implemented and deployed in the SFC controller and SF/SFC proxy to provide mutual authentication between the SFC controller and SF/SFC proxy, as well as providing data confidentiality, data integrity and anti-replay for data transportation over the management interface.
+
+## 11.3 Countermeasures for secure policy management
+
+It is recommended that: 1) the SFC controller authenticates the SFC app, the SDN controller authenticates the SFC controller with PSK-based authentication ([b-IETF RFC 4279], [b-IETF RFC 4306]) and certificate-based authentication ([b-IETF RFC 4306], [b-IETF RFC 5246] etc.), respectively; 2) the SFC controller authorizes the SFC app, the SDN controller authorizes the SFC controller with an ACL, RBAC, etc.; 3) the SFC controller and SDN controller can also set the priority for all flow rules like the proposed mechanism in clause B.1 of [ITU-T X.1038].
+
+# Annex A
+
+## Classification table and service function path forwarding table
+
+(This annex forms an integral part of this Recommendation.)
+
+This annex specifies the classification table and the SFP forwarding table based on the OpenFlow flow table in [b-ONF TS-025] in order to reflect classification rules and SFP forwarding rules. In this way, service function chaining can be implemented based on SDN according to [ITU-T Y.3300].
+
+Table A.1 shows the main components of a flow entry in a flow table specified in [b-ONF TS-025].
+
+**Table A.1 – Main components of a flow entry in an OpenFlow flow table**
+
+| Match fields | Priority | Counters | Instructions | Timeouts | Cookie | Flags |
+|--------------|----------|----------|--------------|----------|--------|-------|
+|--------------|----------|----------|--------------|----------|--------|-------|
+
+Each flow table entry (see Table A.1) contains the following.
+
+- Match fields: To match against packets. These consist of the ingress port and packet headers, and optionally other pipeline fields, e.g., metadata specified by a previous table.
+- Priority: Matching precedence of the flow entry.
+- Counters: Updated when packets are matched.
+- Instructions: To modify the action set or pipeline processing.
+- Timeouts: Maximum amount of time or idle time before flow is expired by the switch.
+- Cookie: Opaque data value chosen by the controller. May be used by the controller to filter flow entries affected by flow statistics, flow modification and flow deletion requests. Not used when processing packets.
+- Flags: flags alter the way flow entries are managed, e.g., the flag OFPFF\_SEND\_FLOW\_REM triggers flow removed messages for that flow entry.
+
+In order to specify the classification table and SFP forwarding table to reflect classification rules and SFP forwarding rules, two components of the flow table in Table A.1 (i.e., "match fields" and "instructions") will be extended. Moreover, some new components of the flow table will also be introduced. The other five components (i.e., "priority", "counters", "timeouts", "cookie" and "flags") will be applied to the classification table and SFP forwarding table without change.
+
+## A.1 Classification table
+
+Compared to Table A.1, Table A.2 shows how to extend two components (i.e., "match fields" and "instructions") and how to introduce new components (i.e., "NSH" and "Next hop") in order to construct a classification table that reflects classification rules.
+
+**Table A.2 – extended components and new components of a flow entry in a classification table**
+
+| Classification table of classifier |                      |               |         |                  |                  |     |    |               |                 |          |                      |                           |
+|------------------------------------|----------------------|---------------|---------|------------------|------------------|-----|----|---------------|-----------------|----------|----------------------|---------------------------|
+| Match fields                       |                      |               |         |                  |                  | NSH |    |               |                 | Next hop | Instruction          |                           |
+|                                    |                      |               |         |                  |                  |     |    |               |                 |          | Apply action         | Goto_table                |
+| Source IP. addr.                   | Destination IP addr. | Protocol type | In port | Application type | User Information | SPI | SI | Next protocol | Context headers | Next Hop | Update packet header | Update header match field |
+
+A description of the extended components and new components in Table A.2 follows.
+
+- Match fields: Referring to the "match fields" (i.e., to match against packets) defined in [b-ONF TS-025], with some extensions in this Recommendation as follows: match fields optionally includes other information about packet payload, e.g., application type and user information.
+- NSH: A new component of a flow entry in a classification table to support the NSH is specified in [b-IETF RFC 8300].
+- Next hop: A new component of a flow entry in the classification table to support the next hop in an SFP which is specified according to service path identifier (SPI) and service index (SI), defined in [b-IETF RFC 8300]. The next hop field is used for the underlying network protocol to establish a tunnel to transport the packet encapsulated by the NSH. For example, if the multi-protocol label switching (MPLS) protocol is used to transport the packet encapsulated by the NSH, more than one label-switched path (LSP) may be established for an SFP if the service functions are deployed in different data centres. An LSP is established between the current node and the next hop node.
+- Instruction: Referring to the "instructions" (i.e., to modify the action set or pipeline processing) specified in [b-ONF TS-025], with some extensions in this Recommendation as follows: pushing the NSH, replacing the destination Internet protocol (IP) address with that of the next hop in order to support establishing an LSP if the protocol MPLS is used to transmit the packet encapsulated with the NSH.
+  - If the MPLS protocol is used to transmit the packet encapsulated with the NSH, the label stack entry of MPLS specified in [b-IETF RFC 3032] may be extended as follows in order to indicate that the transmitted packet is encapsulated with the NSH. In this way, SFC implementation based on SDN can be done.
+  - The label stack entry defined in [b-IETF RFC3032] is described in Table A.3.
+
+**Table A.3 – Label stack entry defined in [b-IETF RFC3032]**
+
+|                |    |    |    |             |
+|----------------|----|----|----|-------------|
+| 0              | 19 | 22 | 23 | 31          |
+| Label: 20 bits |    |    |    | Exp: 3 bits |
+|                |    |    |    | S: 1bit     |
+|                |    |    |    | TTL: 8 bits |
+
+- Label: label value, 20 bits
+- Exp: experimental use, 3 bits, reserved for experimental use
+- S: bottom of stack, 1 bit
+- TTL: time to live, 8 bits
+
+- In order to support NSH encapsulation, 1 bit of Exp as in Table A.4 is used to indicate that its MPLS is used for transport encapsulation
+
+**Table A.4 – Indication that multi-protocol label switching is used for transport encapsulation**
+
+![Diagram of a 32-bit MPLS label structure. Bits 0-19: Label (20 bits). Bits 20-22: Exp (3 bits), with bit 20 labeled 'N' (1 bit). Bit 22: S (1 bit). Bits 23-31: TTL (8 bits).](d734a6ea1b381280f043fcf70391b6db_img.jpg)
+
+0 19 20 22 23 31  
+
+|                |                           |            |             |
+|----------------|---------------------------|------------|-------------|
+| Label: 20 bits | Exp:<br>N: 1bit<br>3 bits | S:<br>1bit | TTL: 8 bits |
+|----------------|---------------------------|------------|-------------|
+
+Diagram of a 32-bit MPLS label structure. Bits 0-19: Label (20 bits). Bits 20-22: Exp (3 bits), with bit 20 labeled 'N' (1 bit). Bit 22: S (1 bit). Bits 23-31: TTL (8 bits).
+
+N: To indicate that MPLS is used for transport encapsulation for the NSH, 1 bit
+
+## A.2 Service function path forwarding table
+
+Compared with Table A.1, Table A.5 shows how to extend two components (i.e., "match fields" and "instructions") and how to introduce new components (i.e., "Next hop") in order to construct an SFP forwarding table that reflects SFP forwarding rules.
+
+**Table A.5 – Extended and new components of a flow entry in a service function path forwarding table**
+
+| SFP table of SFF |    |          |                      |                           |          |            |
+|------------------|----|----------|----------------------|---------------------------|----------|------------|
+| Match fields     |    | Next hop | Instruction          |                           |          |            |
+| SPI              | SI |          | Apply action         |                           |          | Goto_table |
+|                  |    |          | Update Packet header | Update header match field | Out port |            |
+|                  |    |          |                      | Destination IP addr.      |          |            |
+
+Legend:
+
+IP: Internet protocol; SFF: service function forwarder; SFP: service function path;  
+SI: service index; SPI: service path identifier
+
+The extended components and new components in Table A.5 are described as follows.
+
+- Match fields: To extend Table A.1 with some new components of a flow entry to support matching the SPI and SI of the NSH defined in [b-IETF RFC 8300].
+- Next hop: A new component of a flow entry in the SFP forwarding table to support the next hop in an SFP, which is specified according to SPI and SI, defined in [b-IETF RFC 8300]. The next hop field is used for the underlying network protocol to establish a tunnel to transport the packet encapsulated by the NSH.
+
+Instruction: referring to the "instructions" (i.e., to modify the action set or pipeline processing) defined in [b-ONF TS-025], with some extensions in this Recommendation as follows: popping NSH, replacing the destination IP address with the IP address of the next hop in order to support the establishment of an LSP, if the MPLS protocol is used to transmit the packet encapsulated with the NSH.
+
+# Appendix I
+
+## Service function chain architecture specified by other standards development organizations
+
+(This appendix does not form an integral part of this Recommendation.)
+
+Figure I.1 is taken from Figure 3 of [b-IETF RFC 7665].
+
+![Diagram of Service function chain architecture components after initial classification.](4b87467ad9642943235f48f7d4b59449_img.jpg)
+
+The diagram illustrates the service function chain architecture components after initial classification. It shows a central 'SF forwarder (SFF)' box. To its left, an 'SFC-aware SF' box is connected to the SFF via a line with three dots. Above this line is a box labeled 'SFC-aware service function', with a vertical line labeled 'SFC encapsulation' connecting it to the main line. To the right of the SFF, a line connects it to an 'SFC proxy' box, with a vertical line labeled 'SFC encapsulation' connecting this line to a box above labeled 'SFC-unaware service function'. From the 'SFC proxy' box, a vertical line labeled 'No SFC encapsulation' connects to the 'SFC-unaware service function' box. Below the 'SF forwarder (SFF)' box, a vertical line labeled 'SFC encapsulation' connects to the text '... SFC-enabled domain ...'. Below this text, another vertical line labeled 'Network overlay transport' connects to an oval labeled 'Network'. The identifier 'X.1043(19)\_FI.1' is located at the bottom right of the diagram.
+
+Diagram of Service function chain architecture components after initial classification.
+
+**Figure I.1 – Service function chain architecture components after initial classification [b-IETF RFC 7665]**
+
+The architecture in Figure I.1 only describes the network elements in the data plane, i.e., SFF, SF and SFC proxy. The classifier is not included in Figure 6-1 because it shows architecture after initial classification.
+
+Figure I.2 is taken from section 4 of [b-ONF TS-027].
+
+![Figure I.2 – L4-L7 software-defined networking service function chain architecture [b-ONF TS-027]. The diagram illustrates a multi-tier architecture. At the top, 'SFC clients' (green box) connect to a 'Service function chain orchestrator' (light blue box) via an 'SFC NBI' (red text). The orchestrator contains an 'SFC manager' and an 'SF instance catalogue manager'. The 'SFC manager' connects to 'SFC network controller 1' and 'SFC network controller n' (red boxes) via an 'SFC specification interface' (red text). The 'SF instance catalogue manager' connects to an 'SF instance manager (third party)' (blue box) via an 'SFI registration interface' (red text). Both network controllers connect to the network plane via 'OpenFlow' (red text). The network plane consists of a 'Source' (blue oval) connected to a 'Classifier' (blue box), which leads to a cloud containing 'FW' (blue box), 'LB' (blue box), and 'IDS/IPS' (blue box). This cloud connects to an 'SF forwarder (OF-Switch)' (blue box), which then connects to another cloud containing 'Cache' (blue box), 'QoS' (blue box), and 'WOC' (blue box). This second cloud connects to a 'Destination' (blue oval). Dashed lines indicate control and management paths from the orchestrator and instance manager to the network plane components.](7133ccf78043568ca62ecbcd43628a4a_img.jpg)
+
+Figure I.2 – L4-L7 software-defined networking service function chain architecture [b-ONF TS-027]. The diagram illustrates a multi-tier architecture. At the top, 'SFC clients' (green box) connect to a 'Service function chain orchestrator' (light blue box) via an 'SFC NBI' (red text). The orchestrator contains an 'SFC manager' and an 'SF instance catalogue manager'. The 'SFC manager' connects to 'SFC network controller 1' and 'SFC network controller n' (red boxes) via an 'SFC specification interface' (red text). The 'SF instance catalogue manager' connects to an 'SF instance manager (third party)' (blue box) via an 'SFI registration interface' (red text). Both network controllers connect to the network plane via 'OpenFlow' (red text). The network plane consists of a 'Source' (blue oval) connected to a 'Classifier' (blue box), which leads to a cloud containing 'FW' (blue box), 'LB' (blue box), and 'IDS/IPS' (blue box). This cloud connects to an 'SF forwarder (OF-Switch)' (blue box), which then connects to another cloud containing 'Cache' (blue box), 'QoS' (blue box), and 'WOC' (blue box). This second cloud connects to a 'Destination' (blue oval). Dashed lines indicate control and management paths from the orchestrator and instance manager to the network plane components.
+
+**Figure I.2 – L4-L7 software-defined networking service function chain architecture [b-ONF TS-027]**
+
+The architecture in Figure I.2 is Open Networking Foundation (ONF) SDN-based and the intent is to build a common base for concrete northbound interface (NBI) specifications and OpenFlow extensions needed for SFC.
+
+# Bibliography
+
+- [b-IETF RFC 2104] IETF RFC 2104 (1997), *HMAC: Keyed-hashing for message authentication*.
+- [b-IETF RFC 3032] IETF RFC 3032 (2001), *MPLS label stack encoding*.
+- [b-IETF RFC 4210] IETF RFC 4210 (2005), *Internet X.509 public key infrastructure certificate management protocol (CMP)*.
+- [b-IETF RFC 4279] IETF RFC 4279 (2005), *Pre-shared key ciphersuites for transport layer security (TLS)*.
+- [b-IETF RFC 4301] IETF RFC 4301 (2005), *Security architecture for the Internet protocol*.
+- [b-IETF RFC 4303] IETF RFC 4303 (2005), *IP encapsulating security payload (ESP)*.
+- [b-IETF RFC 4306] IETF RFC 4306 (2005), *Internet key exchange (IKEv2) protocol*.
+- [b-IETF RFC 4835] IETF RFC 4835 (2007), *Cryptographic algorithm implementation requirements for encapsulating security payload (ESP) and authentication header (AH)*.
+- [b-IETF RFC 5246] IETF RFC 5246 (2008), *The transport layer security (TLS) protocol, version 1.2*.
+- [b-IETF RFC 7665] IETF RFC 7665 (2015), *Service function chaining (SFC) architecture*.
+- [b-IETF RFC 8300] IETF RFC 8300 (2018), *Network service header (NSH)*.
+- [b-ONF TS-025] ONF TS-025 (2015), *OpenFlow switch specification, v.1.5.1*. Available [viewed 2019-05-08] at: <https://www.opennetworking.org/wp-content/uploads/2014/10/openflow-switch-v1.5.1.pdf>
+- [b-ONF TS-027] ONF TS-027 (2015), *L4-L7 service function chaining solution architecture, v.1.0*. Available [viewed 2019-05-09] at: [https://www.opennetworking.org/wp-content/uploads/2014/10/L4-L7\\_Service\\_Function\\_Chaining\\_Solution\\_Architecture.pdf](https://www.opennetworking.org/wp-content/uploads/2014/10/L4-L7_Service_Function_Chaining_Solution_Architecture.pdf)
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| Series F        | Non-telephone telecommunication services                                                                                                                  |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| <b>Series X</b> | <b>Data networks, open system communications and security</b>                                                                                             |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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@@ -0,0 +1,714 @@
+
+
+I n t e r n a t i o n a l   T e l e c o m m u n i c a t i o n   U n i o n
+
+# ITU-T
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+# X.1046
+
+(12/2020)
+
+SERIES X: DATA NETWORKS, OPEN SYSTEM  
+COMMUNICATIONS AND SECURITY
+
+Information and network security – Network security
+
+# --- **Framework of software-defined security in software-defined networks/network functions virtualization networks**
+
+Recommendation ITU-T X.1046
+
+ITU-T
+
+![ITU logo](1d7527f4316cfe2d342b08d1653d1592_img.jpg)
+
+The logo of the International Telecommunication Union (ITU), featuring a blue globe with a network of lines and the letters 'ITU' in the center.
+
+ITU logo
+
+## ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY
+
+|                                                        |                      |
+|--------------------------------------------------------|----------------------|
+| PUBLIC DATA NETWORKS                                   | X.1–X.199            |
+| OPEN SYSTEMS INTERCONNECTION                           | X.200–X.299          |
+| INTERWORKING BETWEEN NETWORKS                          | X.300–X.399          |
+| MESSAGE HANDLING SYSTEMS                               | X.400–X.499          |
+| DIRECTORY                                              | X.500–X.599          |
+| OSI NETWORKING AND SYSTEM ASPECTS                      | X.600–X.699          |
+| OSI MANAGEMENT                                         | X.700–X.799          |
+| SECURITY                                               | X.800–X.849          |
+| OSI APPLICATIONS                                       | X.850–X.899          |
+| OPEN DISTRIBUTED PROCESSING                            | X.900–X.999          |
+| INFORMATION AND NETWORK SECURITY                       |                      |
+| General security aspects                               | X.1000–X.1029        |
+| <b>Network security</b>                                | <b>X.1030–X.1049</b> |
+| Security management                                    | X.1050–X.1069        |
+| Telebiometrics                                         | X.1080–X.1099        |
+| SECURE APPLICATIONS AND SERVICES (1)                   |                      |
+| Multicast security                                     | X.1100–X.1109        |
+| Home network security                                  | X.1110–X.1119        |
+| Mobile security                                        | X.1120–X.1139        |
+| Web security                                           | X.1140–X.1149        |
+| Security protocols (1)                                 | X.1150–X.1159        |
+| Peer-to-peer security                                  | X.1160–X.1169        |
+| Networked ID security                                  | X.1170–X.1179        |
+| IPTV security                                          | X.1180–X.1199        |
+| CYBERSPACE SECURITY                                    |                      |
+| Cybersecurity                                          | X.1200–X.1229        |
+| Countering spam                                        | X.1230–X.1249        |
+| Identity management                                    | X.1250–X.1279        |
+| SECURE APPLICATIONS AND SERVICES (2)                   |                      |
+| Emergency communications                               | X.1300–X.1309        |
+| Ubiquitous sensor network security                     | X.1310–X.1319        |
+| Smart grid security                                    | X.1330–X.1339        |
+| Certified mail                                         | X.1340–X.1349        |
+| Internet of things (IoT) security                      | X.1360–X.1369        |
+| Intelligent transportation system (ITS) security       | X.1370–X.1389        |
+| Distributed ledger technology security                 | X.1400–X.1429        |
+| Distributed ledger technology security                 | X.1430–X.1449        |
+| Security protocols (2)                                 | X.1450–X.1459        |
+| CYBERSECURITY INFORMATION EXCHANGE                     |                      |
+| Overview of cybersecurity                              | X.1500–X.1519        |
+| Vulnerability/state exchange                           | X.1520–X.1539        |
+| Event/incident/heuristics exchange                     | X.1540–X.1549        |
+| Exchange of policies                                   | X.1550–X.1559        |
+| Heuristics and information request                     | X.1560–X.1569        |
+| Identification and discovery                           | X.1570–X.1579        |
+| Assured exchange                                       | X.1580–X.1589        |
+| CLOUD COMPUTING SECURITY                               |                      |
+| Overview of cloud computing security                   | X.1600–X.1601        |
+| Cloud computing security design                        | X.1602–X.1639        |
+| Cloud computing security best practices and guidelines | X.1640–X.1659        |
+| Cloud computing security implementation                | X.1660–X.1679        |
+| Other cloud computing security                         | X.1680–X.1699        |
+| QUANTUM COMMUNICATION                                  |                      |
+| Terminologies                                          | X.1700–X.1701        |
+| Quantum random number generator                        | X.1702–X.1709        |
+| Framework of QKDN security                             | X.1710–X.1711        |
+| Security design for QKDN                               | X.1712–X.1719        |
+| Security techniques for QKDN                           | X.1720–X.1729        |
+| DATA SECURITY                                          |                      |
+| Big Data Security                                      | X.1750–X.1759        |
+| 5G SECURITY                                            | X.1800–X.1819        |
+
+## Recommendation ITU-T X.1046
+
+# Framework of software-defined security in software-defined networks/network functions virtualization networks
+
+## Summary
+
+Recommendation ITU-T X.1046 specifies a framework of software-defined security in software-defined networks (SDNs) and the network functions virtualization (NFV) networks. This framework utilizes key advantages of SDN/NFV technologies such as on-demand capacity scale-in/scale-out, dynamic and intelligent security policy control regarding real-time network status, separated deployment of control layer and data forwarding layer, full view of traffic for monitoring and unified security policy setting.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T X.1046   | 2020-12-14 | 17          | <a href="http://handle.itu.int/11.1002/1000/14442">11.1002/1000/14442</a> |
+
+## Keywords
+
+SDN/NFV security, security controller, software-defined security.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2021
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                          | <b>Page</b> |
+|--------------------------------------------------------------------------|-------------|
+| 1 Scope .....                                                            | 1           |
+| 2 References.....                                                        | 1           |
+| 3 Definitions .....                                                      | 1           |
+| 3.1 Terms defined elsewhere.....                                         | 1           |
+| 3.2 Terms defined in this Recommendation.....                            | 1           |
+| 4 Abbreviations and acronyms .....                                       | 3           |
+| 5 Conventions .....                                                      | 4           |
+| 6 Overview .....                                                         | 5           |
+| 7 Security challenges for SDN/NFV network .....                          | 5           |
+| 8 Requirements for software-defined security in SDN/NFV networks.....    | 6           |
+| 9 Reference framework of software-defined security .....                 | 6           |
+| 9.1 Reference framework .....                                            | 6           |
+| 9.2 Components.....                                                      | 8           |
+| 9.3 Interfaces .....                                                     | 11          |
+| 9.4 Lifecycle management of virtualized security function instance ..... | 12          |
+| 10 Reference implementation of software-defined security .....           | 15          |
+| 10.1 Software-defined security deployment in NFV environment .....       | 15          |
+| 10.2 Software-defined security deployment in SD-WAN.....                 | 16          |
+| Bibliography.....                                                        | 18          |
+
+# **Introduction**
+
+In recent years traditional telecommunication networks have shown their disadvantages such as long construction cycles, high costs and poor flexibility. These constraints are most evident in the slowdown on the development and deployment of emerging services.
+
+The introduction of software-defined networks (SDNs) and network functions virtualization (NFV) technologies fundamentally changes the way networks are built and operated, mainly by taking advantage of general-purpose hardware, virtualization software and programmable services. With SDN and NFV, network operation and maintenance costs are reduced, resource utilization is improved, network flexibility is increased, and time-to-market of new services is considerably decreased.
+
+SDN and NFV are considered as innovation technologies for telecommunications network evolution. However, these technologies bring new security challenges for telecommunications networks. Traditional security concepts based on static, passive, separate and manual operations of security defence systems do not work well in the SDN/NFV network environment. New security concepts based on dynamic, proactive, centralized and intelligent security management capabilities are needed.
+
+This Recommendation provides a framework of software-defined security in SDN/NFV networks. This framework utilizes key advantages of SDN/NFV technologies such as on-demand capacity scale-in/scale-out, dynamic and intelligent security policy control regarding real-time network status, separated deployment of control layer and data forwarding layer, full view of traffic for monitoring and unified security policy setting. This framework is a layered framework, it provides security orchestration, centralized and automated security policy management, and intelligent security analysis and response.
+
+## Recommendation ITU-T X.1046
+
+## Framework of software-defined security in software-defined networks/network functions virtualization networks
+
+# 1 Scope
+
+This Recommendation specifies a framework of software-defined security in software-defined networks (SDNs) and the network functions virtualization (NFV) networks. This Recommendation provides the following:
+
+- analysis of the main security challenges including technical and operational aspects in telecom operators' SDN/NFV based networks;
+- summarization of security requirements to address these challenges in SDN/NFV networks;
+- introduction of the concept of 'software-defined security' based on identified requirements;
+- definition of a framework for 'software-defined security' with functionality requirements for each component; and
+- guidelines on implementation of software-defined security.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [ITU-T X.1038] Recommendation ITU-T X.1038 (2016), *Security requirements and reference architecture for software-defined networking*.
+- [ITU-T Y.3300] Recommendation ITU-T Y.3300 (2014), *Framework of software-defined networking*.
+- [ITU-R M.1224-1] Recommendation ITU-R M.1224-1 (2012), *Vocabulary of terms for International Mobile Telecommunications (IMT)*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 security policy** [ITU-R M.1224-1]: A set of rules which define and constrain the types of security-relevant activities of entities and parties.
+
+**3.1.2 policy conflict** [b-ITU-T X.1036]: It defines the actions of two rules contradicting each other. The entity implementing the policy will not be able to determine which action to perform. To prevent this situation, the implementers of policy systems must provide conflict detection and avoidance or resolution mechanisms.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 distribution of security policy:** A capability to distribute security policies to security functions.
+
+**3.2.2 flow collection function:** A function for collecting network traffic so as to identify security threats. Commonly used technologies are those such as IP flow information export (IPFIX) [b-IETF RFC 3917] and sFlow [b-IETF RFC 3176].
+
+**3.2.3 forwarding policy:** A set of rules which are distributed to switches by a SDN controller to indicate the way switches should forward network traffic.
+
+**3.2.4 lifecycle management of virtualized security function instance:** A set of functions required to manage the instantiation, maintenance and termination of a virtualized security function.
+
+**3.2.5 network topology:** Configuration of links connecting cross-connect physical devices (e.g., physical network device, physical security device) and virtualized functions such as virtualized network function (VNF) and virtualized security function (VSF).
+
+**3.2.6 optimization of security policy:** Capabilities and operations to detect the activated security policies, redundant policies, usage frequencies, etc. and implement optimizations such as deleting non-activated security policies, merging or deleting redundant policies, etc.
+
+**3.2.7 security configuration parameter:** A set of parameters which describe the features of the security function, such as maximum bandwidth, maximum number of connections, etc. supported by the security function, protected object and security actions of the security function.
+
+**3.2.8 security device:** A physical device that provides security functions (e.g., firewalls, IDs, security gateways, and security management servers).
+
+**3.2.9 security information and event management system:** A security and audit system that supports threat detection, compliance and security incident management through the analysis of security events.
+
+NOTE – The security information and event management system collects, manages and analyses log events, and then produces operational advice or operates according to the results of the analysis.
+
+**3.2.10 security function vendor:** A creator of a security function that provides physical/hardware security devices or software which executes security actions.
+
+**3.2.11 security function:** Capabilities implemented in a physical/hardware device or by a software which executes security actions [b-UNISAFE] (e.g., detecting security malicious URLs, dropping a traffic, detecting DoS/DDoS attacks, scanning and removing viruses, traffic limit, access control based on source IP or destination IP, etc.) according to security policies.
+
+**3.2.12 security policy conflict:** A contradiction when two security policies deal with the same flow, for example, one security policy is to drop a flow and another is to forward the flow.
+
+**3.2.13 service resource:** A set of network devices in the telecom operator's network, which work together to deliver services to the telecom operator's customers.
+
+**3.2.14 security situation:** Security information which is collected through continuous monitoring activities on a network in order to detect anomalies and potential security threats.
+
+**3.2.15 security situation awareness:** Capability to provide information about the security situation.
+
+**3.2.16 SDN controller:** A dedicated network element which provides a means to program, orchestrate, control and manage the network resources through software (i.e., SDN applications).
+
+NOTE – Definition adapted from [ITU-T Y.3300].
+
+**3.2.17 software-defined security:** Technologies enabling security capabilities such as decoupling of the security control plane with the enforcement plane of physical security devices, centralization of a decoupled security control plane, and opening of a programmable interface can achieve
+
+uniformed identification of security functions, security function deployment on demand, collaborative work between security functions, automatic and on-demand distribution and configuration of security policies.
+
+**3.2.18 state of security function:** A set of parameters that describe the supported resource state of the security function (e.g., central processing unit (CPU) capability, maximum bandwidth and throughput, etc.) and the usage state of the resources (e.g., CPU utilization, memory utilization, bandwidth utilization, etc.).
+
+**3.2.19 virtualized security function (VSF):** A virtualized implementation of a security function that is deployed on a virtualization infrastructure such as an NFV virtualization infrastructure (NFVI).
+
+**3.2.20 virtualized security function instance:** The run-time instantiation of the virtualized security function (VSF) software resulting from completing the instantiation of its components and of the connectivity between them, and using the virtualized network function (VNF) [b-ETSI NFV 003] deployment and operational information captured in the VNF descriptor of security function, as well as additional run-time instance-specific information and constraints.
+
+**3.2.21 virtualized security function scaling:** An ability to dynamically extend/reduce resources granted to the virtual security function (VSF) as needed. This includes scaling up/down and scaling out/in. Scaling out/in is an ability to scale by add/remove VSF instances. Scaling up/down is an ability to scale by changing allocated resources of VSF, e.g., increase/decrease memory, central processing unit (CPU) capability or storage capacity.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                                           |
+|------|-------------------------------------------|
+| AI   | Artificial Intelligence                   |
+| API  | Application Programming Interface         |
+| APT  | Advanced Persistent Threat                |
+| AV   | Antivirus                                 |
+| C&C  | Command and Control                       |
+| CPE  | Customer Premise Equipment                |
+| CPU  | Central Processing Unit                   |
+| DoS  | Denial of Service                         |
+| DDoS | Distributed Denial of Service             |
+| EMS  | Element Management System                 |
+| FW   | Firewall                                  |
+| IP   | Internet Protocol                         |
+| IPS  | Intrusion Prevention System               |
+| MANO | Management and Orchestration              |
+| NFV  | Network Function Virtualization           |
+| NFVI | NFV Virtualization Infrastructure         |
+| NTQ  | Network Topology Query                    |
+| OAM  | Operation, Administration and Maintenance |
+| OSS  | Operation Support System                  |
+
+|         |                                                            |
+|---------|------------------------------------------------------------|
+| RESTful | Representational State Transfer                            |
+| SD-WAN  | Software-Defined Wide Area Network                         |
+| SDN     | Software-Defined Network                                   |
+| SFR     | Security Function Registry                                 |
+| SFSM    | Security Function State Management                         |
+| SIEM    | Security Information and Event Management                  |
+| SPCD    | Security Policy Conflict Detection                         |
+| SPDO    | Security Policy Distributing and Optimizing                |
+| SPM     | Security Policy Manager                                    |
+| SPMA    | Security Policy Management                                 |
+| SPR&SFS | Security Policy Resolution and Security Function Selection |
+| SPS     | Security Policy Repository                                 |
+| TLS     | Transport Layer Security                                   |
+| URL     | Uniform Resource Locator                                   |
+| vIPS    | Virtual Intrusion Prevention System                        |
+| VLAN    | Virtual Local Area Network                                 |
+| VM      | Virtual Machine                                            |
+| VNF     | Virtualized Network Function                               |
+| VNFC    | VNF Component                                              |
+| VNFM    | VNF Manager                                                |
+| VPN     | Virtual Private Network                                    |
+| VSF     | Virtualized Security Function                              |
+| VSRM    | Virtualized Security Resource Management                   |
+| WAN     | Wide Area Network                                          |
+
+# 5 Conventions
+
+In this Recommendation:
+
+The keywords "is required to" indicate a requirement which must be strictly followed and from which no deviation is permitted, if conformance to this Recommendation is to be claimed.
+
+The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+
+The keyword "operator" indicates telecom operator.
+
+*Italics* are used in this Recommendation to indicate components of security manager and security analyser.
+
+**Bold** fonts are used in this Recommendation to indicate layers in the framework of software-defined security in software-defined networks/network functions virtualization networks.
+
+# 6 Overview
+
+In recent years traditional telecommunications networks have revealed disadvantages such as long construction cycles, high costs and poor flexibility. These constraints are most evident in the slowdown on the development and deployment of emerging services. The introduction of software defined networks (SDNs) and network functions virtualization (NFV) technologies fundamentally changes the way networks are built and operated, mainly by taking advantage of general purpose hardware, virtualization software and programmable services. With NFV providing automatic on-demand virtualized resource management and SDN offering automatic routing together with finer granularity of policies on network configuration and data flow scheduling, network operation and maintenance costs are reduced, resource utilization is improved, network flexibility is increased and time-to-market for new services is considerably decreased.
+
+These changes also affect the security of these new telecommunications networks. Traditional static, passive, separate and manual operations of security defence systems do not work well in new cloud-based SDN/NFV networks. A new security system architecture is needed to meet the urgent requirement of dynamic, proactive and intelligent security management within SDN/NFV networks.
+
+# 7 Security challenges for SDN/NFV network
+
+SDN and NFV are considered innovative technologies driving the evolution of telecommunication networks. They improve network flexibility and reduce deployment and operation costs. However new security challenges are also introduced and should be addressed. These security challenges are divided into two aspects: (1) security challenges of SDN and NFV, and (2) management and operation challenges to security policy and security devices. These security challenges are described in detail as follows:
+
+## (1) Security challenges of SDN and NFV:
+
+- spoofing and DoS attacks for SDN controller [ITU-T X.1038];
+- flow rules confliction on SDN controller [ITU-T X.1038];
+- loss of confidentiality and integrity in NFV [b-ETSI NFV-SEC 003].
+
+[ITU-T X.1038] specified security requirements and reference architecture for SDN. The security requirements of NFV were defined by the ETSI specification [b-ETSI NFV-SEC 003]. Therefore, the security requirements of SDN and NFV will not be included in this Recommendation.
+
+## (2) Management and operation challenges to security policy and security functions:
+
+- the physical security boundary becomes blurred after introducing virtualization. This means traditional protection methods, which depend on deploying security devices and setting security policies at physical boundaries, cannot meet the protection requirements of virtualized boundaries;
+- various kinds of security devices lead to complicated security management and operation issues. Security devices from different security device vendors have different configuration and operation mechanisms. This increases administrator workloads and may result in misconfiguration;
+- scalability of security devices is difficult and costly. The scaling of traditional security devices (such as traditional telecommunication network devices) requires procedures for purchase, deployment and operations. These procedures impose long-term and costly impacts;
+- single point protection of security devices leads to limited protection capabilities within the operators' networks. SDN and NFV result in new security challenges for operators' networks. For example, virtualization results in invisible communications between two VNFs that are running on the same host. Attacks between these two VNFs cannot be identified by traditional security detection methods. Thus, the passive defence of a
+
+- single point security device cannot identify new types of attacks, advanced persistent threats (APTs), etc., introduced by VNFs;
+- dynamic VNF creation and deletion lead to complicated security management and operation issues. Traditional operators' networks utilize security devices deployed in specific locations (i.e., physical boundaries) that are operated manually. Therefore, it may be impossible to deploy security policies sufficiently quickly and correctly when VNFs are used. This may result in attacks for VNFs, e.g., an attacker targets a VNF which has not loaded the proper security protection mechanism.
+
+# 8 Requirements for software-defined security in SDN/NFV networks
+
+To address the security challenges to management of security policies and security functions as identified in (2) in clause 7, in SDN/NFV networks, security requirements related to management of security policies and security functions in SDN/NFV networks are defined as follows:
+
+- 1) it is recommended that security functions and security policies are deployed on demand;
+- 2) it is recommended that security functions are uniformly identified and managed;
+- 3) it is recommended to offer virtualized security functions in order to enable fast deployment, efficient operation and cost reduction;
+- 4) it is recommended that security functions collaboratively work together to proactively defend against security threats;
+- 5) it is recommended that security policies are generated quickly and automatically distributed and configured.
+
+To meet the above security requirements, the concept of software-defined security is proposed in this Recommendation. Software-defined security is based on SDN/NFV technologies and has the capabilities of decoupling the control plane with the enforcement plane of physical security devices, centralization of the decoupled control plane and an open programmable interface, which can realize deployment and scaling of a security function on-demand, centralized managing and configuring of a security function and security policy, etc.
+
+Clause 9 proposes the reference framework of software-defined security with related components and interfaces. The **security managed control and analysis layer** in the framework of software-defined security centrally manages the security functions and security policies, deploys the security functions and security policies according to the security configuration parameters of the **security service layer**. It coordinates the work among the security functions to realize proactively. The virtualized security functions of the **security enforcement layer** can be scaled on demand through cooperation between the **security managed control and analysis layer** and NFV MANO [b-ETSI NFV 003]/SDN controller [ITU-T Y.3300].
+
+Clause 10 proposes two implementations of software-defined security so as to guide the deployment of the software-defined security framework.
+
+# 9 Reference framework of software-defined security
+
+## 9.1 Reference framework
+
+Considering the benefits of SDN and NFV, physical security devices and virtualized security functionalities can be offered to support on-demand, quick deployment and implementation, as well as flexible scaling. Furthermore, decoupling the control plane with the enforcement plane of physical security devices and centralization of the decoupled control plane can achieve uniform identification of security functions, collaborative work between security functions, and automatic and on-demand distribution and configuration of security policies. Figure 1 illustrates a reference framework of software-defined security.
+
+![Figure 1: Reference framework of software-defined security. The diagram shows three layers: Security service layer, Security managed control and analysis layer, and Security enforcement layer. The Security service layer includes Anti-DDoS, Anti-AV, Content management, Trace of attack, Threat trend awareness, and Security service chain. The Security managed control and analysis layer includes a Security manager and a Security analyser. The Security enforcement layer includes FW/vFW, IPS/vIPS, DDoS/vDDoS, DFW, WAF/vWAF, and vAR/AR. A Network control and orchestration layer includes an SDN controller and NFV MANO. Service resources include TAS AS, IP-SM-GW, SMSC, BRAS, HSS, and CSCF. Northbound interfaces connect the Security service layer to the Security managed control and analysis layer. Southbound interfaces connect the Security managed control and analysis layer to the Security enforcement layer. Flow scheduling and resource orchestration connects the Network control and orchestration layer to the Service resource layer.](af7916c89a458fdab6c3f443217388ae_img.jpg)
+
+X.1046(20)\_F01
+
+Figure 1: Reference framework of software-defined security. The diagram shows three layers: Security service layer, Security managed control and analysis layer, and Security enforcement layer. The Security service layer includes Anti-DDoS, Anti-AV, Content management, Trace of attack, Threat trend awareness, and Security service chain. The Security managed control and analysis layer includes a Security manager and a Security analyser. The Security enforcement layer includes FW/vFW, IPS/vIPS, DDoS/vDDoS, DFW, WAF/vWAF, and vAR/AR. A Network control and orchestration layer includes an SDN controller and NFV MANO. Service resources include TAS AS, IP-SM-GW, SMSC, BRAS, HSS, and CSCF. Northbound interfaces connect the Security service layer to the Security managed control and analysis layer. Southbound interfaces connect the Security managed control and analysis layer to the Security enforcement layer. Flow scheduling and resource orchestration connects the Network control and orchestration layer to the Service resource layer.
+
+**Figure 1 – Reference framework of software-defined security**
+
+The reference framework of software-defined security includes three layers and two interfaces:
+
+- **Security service layer:** This layer describes security services provided by telecom operators, e.g., anti-distributed denial of service (DDoS), antivirus (AV), security service chain, etc. A request from a customer for a security service that includes its related security configuration parameters (e.g., required network bandwidth, protected source and destination IP addresses), is sent to the **security managed control and analysis layer** through the northbound interface.
+- **Security managed control and analysis layer:** This layer sits in the centre of this reference framework of software-defined security. It includes a security manager and a security analyser.
+- The security manager manages security functions according to the security configuration parameters, which are generated from the **security service layer** or the security analyser. The security manager maps the received security configuration parameters to security policies. The security manager also collaborates with the SDN controller [ITU-T Y.3300], NFV management and orchestration (MANO) [b-ETSI NFV 003] to achieve flow scheduling and security resources orchestration [ITU-T Y.3300], [b-ETSI NFV IFA 010].
+- The security analyser sends security configuration parameters to the security manager after analysing security logs and flows. The security logs and flows are gathered from security functions in the **security enforcement layer** and from network devices in 'service resource' respectively. The security analyser also provides security data such as threat trend awareness to the **security service layer**.
+- **Security enforcement layer:** This layer describes virtualized security functions (VSF) and physical security devices which enforce security policy for flows and packages. These security policies are sent by the **security managed control and analysis layer**. NFV MANO [b-ETSI NFV 003] orchestrates and manages the virtualized resource and lifecycle of a virtualized security function, e.g., providing CPU resources for the virtualized security function, creating a new virtualized security function, etc.
+- **Northbound interfaces:** This is the interface between the **security service layer** and the **security managed control and analysis layer**.
+- **Southbound interfaces:** This is the interface between the **security managed control and analysis layer** and the **security enforcement layer**.
+
+Detailed descriptions of the components and the interfaces of the reference framework of software-defined security are described in the following clauses.
+
+## 9.2 Components
+
+### 9.2.1 Security manager
+
+The security manager is responsible for management of security functions and security policies according to received security configuration parameters from the **security service layer** and /or the security analyser. Figure 2 describes the components which are included in the security manager.
+
+![Figure 2: Components in security manager. The diagram shows a hierarchical structure. At the top is the 'Security service layer' containing 'Security service 1', 'Security service 2', 'Security service 3', and an ellipsis. This layer connects to the 'Security manager' block. The 'Security manager' is divided into two main sections: 'SPM' (Security Policy Manager) and 'SFM' (Security Function Manager). The 'SPM' section includes 'NTQ', 'SPR&SFS', 'SPCD', 'SPDO', and 'SPS'. The 'SFM' section includes 'SFSM', 'VSRM', and 'SFR'. To the right of the 'Security manager' is the 'Security analyser' block, which connects to 'NFV MANO' and 'SDN controller'. At the bottom is the 'Security enforcement layer' containing multiple 'Security function' blocks. Arrows indicate data flow from the service layer to the SPM, from SPM to SFM, and from both SFM and the analyser to the enforcement layer. A reference 'X.1046(20)_F02' is at the bottom right.](a33da0f14e456f92539ce3e9b7d81f9a_img.jpg)
+
+X.1046(20)\_F02
+
+Figure 2: Components in security manager. The diagram shows a hierarchical structure. At the top is the 'Security service layer' containing 'Security service 1', 'Security service 2', 'Security service 3', and an ellipsis. This layer connects to the 'Security manager' block. The 'Security manager' is divided into two main sections: 'SPM' (Security Policy Manager) and 'SFM' (Security Function Manager). The 'SPM' section includes 'NTQ', 'SPR&SFS', 'SPCD', 'SPDO', and 'SPS'. The 'SFM' section includes 'SFSM', 'VSRM', and 'SFR'. To the right of the 'Security manager' is the 'Security analyser' block, which connects to 'NFV MANO' and 'SDN controller'. At the bottom is the 'Security enforcement layer' containing multiple 'Security function' blocks. Arrows indicate data flow from the service layer to the SPM, from SPM to SFM, and from both SFM and the analyser to the enforcement layer. A reference 'X.1046(20)\_F02' is at the bottom right.
+
+**Figure 2 – Components in security manager**
+
+The security manager includes the *security policy manager (SPM)* component and the *security function manager (SFM)* component which are composed by some sub-components.
+
+#### Security policy manager (SPM)
+
+The *security policy manager* includes: the *security policy resolution and security function selection (SPR&SFS)* component, the *security policy conflict detection (SPCD)* component, the *security policy distributing and optimizing (SPDO)* component, the *network topology query (NTQ)* component, and the *security policy repository (SPS)* component. The capabilities of each component are described as follows:
+
+- *Security policy resolution and security function selection (SPR&SFS)*: After receiving security configuration parameters from the **security service layer** or the security analyser, *SPR&SFS* is responsible for mapping the received security configuration parameters to security policies. Then *SPR&SFS* selects security function(s) according to the security policies.
+- When a security configuration parameter from the **security service layer** or the security analyser is received, the *SPR&SFS* maps the received security configuration parameter to the appropriate security policy, resolves the security policy which includes the requested security function(s), protected network segment, IP address(es), and traffic handling policy, etc. Then, the *SPR&SFS* queries the state of the security function(s) which related the requested security function(s) from the *security function state management (SFSM)*, and queries the network topology from the *NTQ*. The queried security function states are combined with the queried network topology, the *SPR&SFS* selects the security function according to the security policy. If the required security function cannot be found (e.g., the
+
+running security functions according to the security policy are busy and cannot be used, or there is no required security function in all running security functions), the *SPR&SFS* will initiate a process to create a new required security function instance. In the end, the selected security function instance identifier(s) and the resolved security policy are sent to the *SPCD* component.
+
+- *Security policy conflict detection (SPCD)*: it is responsible for checking whether there is a security policy conflict. After receiving the security function identifier(s) and related security policy, the *SPCD* queries the *security policy repository (SPS)* and combines the network topology which queried from the *NTQ* to check whether there is a security policy conflict. If there is no security policy conflict, the security function identifier(s) and the related security policy are sent to the *SPDO* by the *SPCD*. The security policy is also sent to the *SPS* for storage. Otherwise, the *SPCD* handles the conflicted security policy according to the priority of the security policy or sends an alarm to the administrator.
+- *Security policy distributing and optimizing (SPDO)*: it is responsible for distributing the security policy to the related security function(s) and optimizing the security policies on the security function(s). After receiving the security function identifier(s) and related security policy, the *SPDO* distributes the security policy to the related security functions. The *SPDO* periodically collects the states of the security policies on the security functions to detect the activated security policies, redundant policies, usage frequencies, etc. and optimizes the security policies. The optimized security policies are simulated to evaluate the impact to the service. After successful simulation, the optimized security policies are sent to the security function(s) and the *SPS* respectively, by the *SPDO*.
+- *Network topology query (NTQ)*: it is responsible for querying the network topology through the northbound interface of the SDN controller [ITU-T Y.3300]. The query request can be sent periodically by the *SPR&SFS* and the *SPCD* to the *NTQ*. The network topology information is also sent to the *SPR&SFS* and the *SPCD* by the *NTQ*, after changing the network topology.
+- *Security policy repository (SPS)*: it is responsible for storing the security policies and responding the security policy query requests from the *SPR&SFS* and the *SPCD*. The security policy on a security function is stored with the security function identifier.
+
+#### **Security function manager (SFM)**
+
+The *security function manager* includes: the *security function registry (SFR)* component, the *security function state management (SFSM)* component, and the *virtualized security resource management (VSRM)* component. The capabilities of each component are described as follows:
+
+- *Security function registry (SFR)*: it is responsible for registering the security function. The security function registry information includes security function identifier, version, security function vendor identifier, throughput, bandwidth, CPU, memory, I/O capability, etc. A security function can be registered using the interface between the *SFR* and the security function. The security function provides support to proactively send its registry information to the *SFR* and also provides support to passively send its registry information after receiving the security function registry query request from the *SFR*. The vendor which provides the security function also supports the transformation of the security functions to *SFR* through secure channels to complete security function registration.
+- *Security function state management (SFSM)*: it is responsible for managing the state of the security function. The dynamic states of a security function such as CPU utilization, memory utilization, bandwidth utilization, concurrency, etc. are periodically sent to the *SFSM* by the security function, and are queried by the *SFSM*. The static states of a security function such as CPU, memory, maximum bandwidth, throughput, etc. are queried from the *SFR* by the *SFSM*. The *SFSM* provides security function states to the *SPR&SFS* and the *VSRM*.
+
+- *Virtualized security resource management (VSRM)*: it is responsible for requesting virtualized security function scaling to NFV MANO according to the virtualized security function state or request from the *SPR&SFS*. After successfully scaling or creating a virtualized security function, the scaled virtualized security function is registered to the *SFR*.
+
+### 9.2.2 Security analyser
+
+The security analyser is responsible for analysing the collected security logs from the security functions, and the gathered network flows from the service resource. After detecting the attacks, the security analyser provides security policies to the security manager. Figure 3 describes the components in the security analyser.
+
+![Figure 3: Components in security analyser. The diagram shows a layered architecture. At the top is the 'Security service layer' containing 'Security service 1', 'Security service 2', 'Security service 3', and an ellipsis. Below this is the 'Security analyser' block, which is a large blue rectangle. Inside the 'Security analyser' block, there is a 'DD' (Data Detection) component containing 'File detection', 'Abnormal flow detection', 'C&C detection', and an ellipsis. To the left of the 'DD' component is the 'SPM' (Security Policy Management) component. Below the 'DD' component is the 'DCI' (Data Collection and Initialization) component. To the right of the 'DD' component is the 'Knowledge base' component. Outside the 'Security analyser' block, to the left, is the 'Security manager' component. To the right are 'SIEM', 'Other knowledge base', and 'Service resource' components. At the bottom is the 'Security enforcement layer' containing 'Security function', 'Security function', 'Security function', and an ellipsis. Arrows indicate data flow: from the 'Security service layer' to the 'Security analyser'; from the 'Security manager' to the 'SPM' and 'DCI'; from the 'Security enforcement layer' to the 'DCI'; from the 'DCI' to the 'DD'; from the 'DD' to the 'Knowledge base'; from the 'Knowledge base' to the 'SIEM' and 'Other knowledge base'; and from the 'Service resource' to the 'DCI'.](1a827b10290f33d4fec04d0e8ef7a897_img.jpg)
+
+Figure 3: Components in security analyser. The diagram shows a layered architecture. At the top is the 'Security service layer' containing 'Security service 1', 'Security service 2', 'Security service 3', and an ellipsis. Below this is the 'Security analyser' block, which is a large blue rectangle. Inside the 'Security analyser' block, there is a 'DD' (Data Detection) component containing 'File detection', 'Abnormal flow detection', 'C&C detection', and an ellipsis. To the left of the 'DD' component is the 'SPM' (Security Policy Management) component. Below the 'DD' component is the 'DCI' (Data Collection and Initialization) component. To the right of the 'DD' component is the 'Knowledge base' component. Outside the 'Security analyser' block, to the left, is the 'Security manager' component. To the right are 'SIEM', 'Other knowledge base', and 'Service resource' components. At the bottom is the 'Security enforcement layer' containing 'Security function', 'Security function', 'Security function', and an ellipsis. Arrows indicate data flow: from the 'Security service layer' to the 'Security analyser'; from the 'Security manager' to the 'SPM' and 'DCI'; from the 'Security enforcement layer' to the 'DCI'; from the 'DCI' to the 'DD'; from the 'DD' to the 'Knowledge base'; from the 'Knowledge base' to the 'SIEM' and 'Other knowledge base'; and from the 'Service resource' to the 'DCI'.
+
+**Figure 3 – Components in security analyser**
+
+The security analyser includes the data collection and initialization (*DCI*) component, data detection (*DD*) component, security policy management (*SPMA*) component, and knowledge base component. The capabilities of each component are described as follows:
+
+- *Data collection and initialization (DCI)*: it is responsible for collecting and initializing the security logs on the security functions and the flows from the network devices in the service resource. The security logs and flows are actively sent to the *DCI* by the security functions and the flow collection functions respectively. The flow collection functions could be deployed in the physical switch or deployed as a standalone application. The *DCI* also periodically supports the query the security function and flow collection functions to get the security logs and the network flows respectively. The collected data may be raw network flows containing amounts of unnecessary information. The *DCI* is responsible for the initialization of the collected data, which means to extract useful information (such as security events, application protocols, related metadata, etc.) from the raw network flow. The initialized data is actively or passively sent to the *DD*.
+- *Data detection (DD)*: it is responsible for detecting attacks according to the received initialized data from the *DCI*. Some detection engines such as file detection, abnormal flow detection, C&C detection, etc. are included in this component. Big data analysis and AI are utilized to deeply detect attacks by these detection engines. The *DD* supports the analysis of the data from other systems, e.g., security information and event management (*SIEM*). The
+
+detection result is sent to the *SPMA*. The result could also be sent to the security situation awareness service.
+
+- *Security policy management (SPMA)*: it is responsible for generating the security configuration parameters according to the detection result from the *DD* and sending the security configuration parameters to the security manager.
+- *Knowledge base*: it is responsible for storing the malicious code and virus characteristics, malicious IP/URL/domain name, attack event, etc., which are referred by the *DD*. The *DD* also has capability to store the detected malicious code and virus characteristics, etc.
+
+### 9.2.3 Security function
+
+Security functions are included in the **security enforcement layer**. It is a physical or virtualized security function. After receiving the security policy from the security manager, the security function is responsible for handling flows according to the received security policies, e.g., forwarding flows, dropping flows, etc. The security functions are recommended to have the following capabilities:
+
+- To actively register themselves to the security manager and passively send their registration information to the security manager after receiving the request message 'security function registry query'.
+- To actively send their state to the security manager and passively send their state to the security manager after receiving the request message 'security function state query'.
+- To actively send their security policies state to the security manager and passively send the security policies state to the security manager after receiving the request message 'security policy state query'.
+- To scale up/down and scale out/in as described in clause 3.2.21, which is controlled by NFV MANO [b-ETSI NFV 003].
+
+## 9.3 Interfaces
+
+### 9.3.1 Northbound interfaces
+
+The northbound interfaces are responsible for sending security configuration parameters according to the customer's security service request to the security manager. The security situation from the security analyser is also sent via northbound interfaces to a security situation awareness application. Northbound interfaces could support representational state transfer (RESTful) [b-RESTful] connections which could use transport layer security (TLS) [b-IETF RFC 5246] to protect these communications.
+
+### 9.3.2 Southbound interfaces
+
+The southbound interfaces are responsible for sending security policies to the **security enforcement layer** from the **security managed control and analysis layer**. The security log, registration information and state of the security functions from the **security enforcement layer** to the **security managed control and analysis layer** are also sent through the southbound interfaces. It is recommended to use TLS to protect the communications. The following interfaces are included at least:
+
+- Security policy control interface: This interface is responsible for distributing the security policies from the security manager and collecting security policies from the security functions.
+- Security function management interface: This interface is responsible for transmitting the registration information, state and security logs of the *security function instances* to the security manager and the security analyser respectively.
+
+Figure 4 shows an overview of the northbound and southbound interfaces.
+
+![Figure 4: Overview of the northbound and southbound interfaces. The diagram shows three layers: Security service layer (top), Security managed control and analysis layer (middle), and Security enforcement layer (bottom). Northbound interfaces connect the top two layers, handling security configuration parameters and security situations. Southbound interfaces connect the middle and bottom layers, handling security policy, security registration information, state, and security logs of security function instances.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg)
+
+X.1046(20)\_F04
+
+Figure 4: Overview of the northbound and southbound interfaces. The diagram shows three layers: Security service layer (top), Security managed control and analysis layer (middle), and Security enforcement layer (bottom). Northbound interfaces connect the top two layers, handling security configuration parameters and security situations. Southbound interfaces connect the middle and bottom layers, handling security policy, security registration information, state, and security logs of security function instances.
+
+**Figure 4 – Overview of the northbound and southbound interfaces**
+
+### 9.3.3 Interface details
+
+For further details on northbound and southbound interface implementations, refer to [b-IETF RFC 8329], [b-OASIS OpenC2-L], [b-OASIS OpenC2-H] and [b-OASIS OpenC2-P].
+
+## 9.4 Lifecycle management of virtualized security function instance
+
+### 9.4.1 Creation of new security function instance
+
+The *security manager* will create a new security function instance when it receives a security policy from the **security service layer** or the security analyser when there is no available security function according to the security policy (e.g., there is no required security function in all of the running security functions). Figure 5 describes the detailed procedures of creating a new security function instance.
+
+![Figure 5: Creation of a new security function instance. This sequence diagram shows the interaction between several components: Security service, Security analyser, SPR&SFS, SFSM, VSRM, SFR, and Security function instance. The process involves: 1. Receiving security configuration parameters from the Security service and Security analyser. 2. Resolving security policy in SPR&SFS. 3. Querying security function state in SFSM. 4. Creating a security function request in VSRM. 5. Instantiating the security function in VSRM (interacting with NFV MANO). 6. Registering the security function in SFR and the Security function instance registry. 7. Synchronizing security function state across SFSM, VSRM, SFR, and the Security function instance. 8. Receiving a security function creation response in SPR&SFS. 9. Querying security function state in SFSM.](77464a47f104d0d647b2414591137b64_img.jpg)
+
+X.1046(20)\_F05
+
+Figure 5: Creation of a new security function instance. This sequence diagram shows the interaction between several components: Security service, Security analyser, SPR&SFS, SFSM, VSRM, SFR, and Security function instance. The process involves: 1. Receiving security configuration parameters from the Security service and Security analyser. 2. Resolving security policy in SPR&SFS. 3. Querying security function state in SFSM. 4. Creating a security function request in VSRM. 5. Instantiating the security function in VSRM (interacting with NFV MANO). 6. Registering the security function in SFR and the Security function instance registry. 7. Synchronizing security function state across SFSM, VSRM, SFR, and the Security function instance. 8. Receiving a security function creation response in SPR&SFS. 9. Querying security function state in SFSM.
+
+**Figure 5 – Creation of a new security function instance**
+
+The procedures of creating a new security function instance described in Figure 5 are as follows:
+
+- 1) The *SPR&SFS* receives a security configuration parameter from a security service in the **security service layer** or the security analyser.
+- 2) The *SPR&SFS* maps the received security configuration parameter to an appropriate security policy and then resolves the security policy.
+- 3) The *SPR&SFS* queries the security function state from the *SFSM* component, and finds that there is no available security function according to the extracted security function.
+- 4) The *SPR&SFS* requests the *VSRM* to create the requested security function instance.
+- 5) The *VSRM* requests NFV MANO to instantiate the requested security function.
+- 6) The *VSRM* registers the *security function* (i.e., the instantiated security function) to the *SFR*. The security function instance could also register itself.
+- 7) The security function state is synchronized between the *SPR* and the *SFS*.
+- 8) The *VSRM* sends the security function creation response to the *SPR&SFS*.
+- 9) The *SPR&SFS* sends the security function state query to the *SFSM* after receiving the security function creation response. Then, this component selects the security function instance, and the initial configuration of the security function instance will be implemented (see Figure 7).
+
+### 9.4.2 Deletion of security function instance
+
+A security function instance will be deleted when the *VSRM* finds the security function instance is activated but does not provide security service (such as filtering traffic, detecting abnormal traffic, etc.) for a period of time. Figure 6 describes the detailed process of deleting a security function instance.
+
+![Sequence diagram showing the deletion of a security function instance between SFSM, VSRM, and NFV MANO.](10781f43062bf3e9601a1e086710556c_img.jpg)
+
+```
+
+sequenceDiagram
+    participant SFSM
+    participant VSRM
+    participant NFV MANO
+
+    VSRM->>SFSM: 1. Security function state query
+    VSRM->>NFV MANO: 2. Security function deletion request
+    Note right of NFV MANO: 3. Deleting security function
+    NFV MANO->>VSRM: 4. Security function deletion response
+    VSRM->>SFSM: 5. Security function state query
+
+```
+
+The diagram illustrates the deletion process involving three entities: SFSM, VSRM, and NFV MANO. The sequence is as follows: 1. VSRM sends a 'Security function state query' to SFSM. 2. VSRM sends a 'Security function deletion request' to NFV MANO. 3. NFV MANO performs the internal action 'Deleting security function'. 4. NFV MANO sends a 'Security function deletion response' back to VSRM. 5. VSRM sends another 'Security function state query' to SFSM.
+
+X.1046(20)\_F06
+
+Sequence diagram showing the deletion of a security function instance between SFSM, VSRM, and NFV MANO.
+
+**Figure 6 – Deletion of a security function instance**
+
+The deletion of a security function instance, as shown in Figure 6, includes the following steps:
+
+- 1) The *VSRM* periodically queries the security function state.
+- 2) The *VSRM* sends security function deletion request to NFV MANO when it finds that there is a security function instance but does not provide security service for a period of time. This security function deletion request includes the security function instance identifier, IP address, VLAN ID, etc.
+- 3) NFV MANO deletes the security function instance according to the received request.
+- 4) NFV MANO sends security function deletion response to the *VSRM* to indicate that the security function instance has been deleted.
+
+- 5) The *SFSM* queries the states of the security function instance in the security enforcement layer and updates the stored states of the security function instance.
+
+### 9.4.3 Configuration of security function instance
+
+#### 9.4.3.1 Initial configuration of security function instance
+
+When a new security function instance is created according to the procedures shown in Figure 4, the security manager implements the initial configuration of the security function instance according to the security policy of the security service or the security analyser. Figure 7 describes the detailed procedures of initial configuration for the security function instance.
+
+![Sequence diagram showing the initial configuration of a security function instance. The participants are SPR&SFS, NTQ, SPCD, SPS, SPDO, and Security function instance. The steps are: 1. SPR&SFS sends 'Security function identifier and related security policy' to SPCD. 2. SPCD sends 'Security policy query' to SPS. 3. SPCD sends 'Network topology query' to NTQ. 4. SPCD performs a self-loop 'Security policy conflict detection'. 5. SPCD sends 'Security function identifier and related security policy' to SPDO. 6. SPDO sends 'Security policy' to the Security function instance. 7. SPCD sends 'Security policy synchronization' to SPS.](523ab7b925beb555f88b2e1e1336974f_img.jpg)
+
+```
+
+sequenceDiagram
+    participant SPR&SFS
+    participant NTQ
+    participant SPCD
+    participant SPS
+    participant SPDO
+    participant SFI as Security function instance
+
+    SPR&SFS->>SPCD: 1. Security function identifier and related security policy
+    SPCD->>SPS: 2. Security policy query
+    SPCD->>NTQ: 3. Network topology query
+    SPCD->>SPCD: 4. Security policy conflict detection
+    SPCD->>SPDO: 5. Security function identifier and related security policy
+    SPDO->>SFI: 6. Security policy
+    SPCD->>SPS: 7. Security policy synchronization
+  
+```
+
+Sequence diagram showing the initial configuration of a security function instance. The participants are SPR&SFS, NTQ, SPCD, SPS, SPDO, and Security function instance. The steps are: 1. SPR&SFS sends 'Security function identifier and related security policy' to SPCD. 2. SPCD sends 'Security policy query' to SPS. 3. SPCD sends 'Network topology query' to NTQ. 4. SPCD performs a self-loop 'Security policy conflict detection'. 5. SPCD sends 'Security function identifier and related security policy' to SPDO. 6. SPDO sends 'Security policy' to the Security function instance. 7. SPCD sends 'Security policy synchronization' to SPS.
+
+X.1046(20)\_F07
+
+**Figure 7 – Initial configuration of a security function instance**
+
+The procedures of initial configuration of a security function instance, as shown in Figure 7, include the following steps:
+
+- 1) When a new security function instance is created, the *SPR&SFS* sends the selected security function identifier and related security policy to the *SPCD*.
+- 2) The *SPCD* queries the stored security policy in the *SPS*.
+- 3) The *SPCD* queries the network topology from the *NTQ*.
+- 4) According to the network topology, the *SPCD* uses the security policy conflict detection algorithm to detect the conflict between the received security policy and the stored security policy. If there is no security policy conflict, step 5 will be implemented. Otherwise, the *SPCD* deals with the security policy conflict, such as selecting a security policy according to the priority of the security policy or issuing an alarm to the operation, administration and maintenance (OAM) process.
+- 5) The *SPCD* sends the security function identifier and related security policy to the *SPDO*.
+- 6) The *SPDO* configures the identified security function instance according to the security policy.
+- 7) The *SPCD* synchronizes the security policy to the *SPS*.
+
+#### 9.4.3.2 Deletion of a security function instance configuration
+
+Deleting a configuration of a security function instance can be implemented in the following two scenarios:
+
+- 1) A customer who purchases a security service in the **security service layer** or the security analyser could decide to delete an existing configuration of a security function instance. Deleting the existing configuration of a security function instance will be implemented like the initial configuration of a security function instance in Figure 7. The priority of the security policy which is resolved from the deleting of the existing configuration of the security function instance is required to be set higher, then the security policy will be implemented by the security function instance.
+- 2) The *SPDO* decides to delete a configuration of a security function instance, e.g., this configuration is redundant or out of date and will not be used.
+
+#### 9.4.3.3 Update of a security function instance configuration
+
+Updating of the configuration of a security function instance can be implemented in the following two scenarios:
+
+- 1) Like the configuration deletion of a security function instance, the configuration update of a security function instance can also be implemented like the initial configuration of a security function instance in Figure 7. The priority of the security policy which is resolved from the updating configuration of the security function instance is required to be set higher, and then the security policy will be implemented by the security function instance.
+- 2) The *SPDO* decides to update an existing configuration of a security function instance, e.g., the configuration is out of date.
+
+# 10 Reference implementation of software-defined security
+
+## 10.1 Software-defined security deployment in NFV environment
+
+The deployment of a software-defined security framework in an NFV environment improves the efficiency of the security detection and disposal in the NFV network, as well as the efficiency of the operation and maintenance for the security functions. Figure 8 proposes an example of the deployment of software-defined security in NFV environment.
+
+![Figure 8: Example of a software-defined security deployment in NFV environment. The diagram shows a Security service layer at the top, containing a Security manager and a Security analyser. These connect to a central NFV block. The NFV block is divided into three main sections: a top section for virtualized security functions (vFW, vIPS, vWAF, VNF, etc.), a middle section for Virtualization resource and layer, and a bottom section for Hardware resource. To the right, a MANO block contains NFVO, VNFM, and VIM. Below MANO is an SDN controller. The SDN controller connects to the Hardware resource section of the NFV block. The entire system is labeled X.1046(20)_F08.](73dff6b45b2b9ffd384bab3235f869af_img.jpg)
+
+Figure 8: Example of a software-defined security deployment in NFV environment. The diagram shows a Security service layer at the top, containing a Security manager and a Security analyser. These connect to a central NFV block. The NFV block is divided into three main sections: a top section for virtualized security functions (vFW, vIPS, vWAF, VNF, etc.), a middle section for Virtualization resource and layer, and a bottom section for Hardware resource. To the right, a MANO block contains NFVO, VNFM, and VIM. Below MANO is an SDN controller. The SDN controller connects to the Hardware resource section of the NFV block. The entire system is labeled X.1046(20)\_F08.
+
+**Figure 8 – Example of a software-defined security deployment in NFV environment**
+
+In an NFV environment, the security manager, the security analyser, the **security service layer**, virtualized security function instance, the *virtual network function manager (VNFM)* [b-ETSI NFV 003] and related interfaces can be deployed in the following ways:
+
+- 1) Security manager: it can be a virtualized instance and deployed in virtual machines (VMs), or act as a physical device. With collaborating with NFVO [b-ETSI NFV 003], the security
+
+manager can manage and orchestrate the security functions and security policies. The security manager can also integrate functions of element management system (EMS) [b-ETSI NFV 003] to manage and control the security functions and security policies directly.
+
+- 2) VNFM: the VNFM in Figure 8 manages the lifecycle of VSF.
+- 3) Security analyser: it communicates with the security manager, the security functions and the **security service layer**. It could be virtually implemented or be deployed as a physical device.
+- 4) **Security service layer**: it provides security service to customers and can be integrated into the operation support systems (OSS) as a functional component of the OSS.
+- 5) Virtualized security function instance: it is a security function which runs in VMs as a VNF or a VNF component) (VNFC) [b-ETSI NFV 003] of a VNF, e.g., a virtual firewall (vFW), virtual intrusion prevention system (vIPS), etc.
+- 6) Interface between the security manager and the VNFM [b-ETSI NFV 003]: this interface is used when element management system (EMS) is integrated into the *security manager*. It uses the interface between EMS [b-ETSI NFV 003] and VNFM in [b-ETSI NFV 003] and [b-ETSI NFV 002].
+- 7) Interface between the virtualized security function and the VNFM: it uses the interface between VNF and VNFM in [b-ETSI NFV 003] and [b-ETSI NFV 002].
+
+## 10.2 Software-defined security deployment in SD-WAN
+
+Software-defined wide area network (SD-WAN) technology applies SDN technology to WAN scenarios to realize automatic deployment of virtual private network (VPN) services and to accelerate the service deployment. To provide security service for the enterprise, the operator can deploy software-defined security components in SD-WAN. Figure 9 gives an example of security service provision by software-defined security in SD-WAN.
+
+![Figure 9: Example of security service provision by software-defined security in SD-WAN. The diagram shows a central SD-WAN core with three routers. Above it is a 'Security resource' block containing vSwitch, vIPS, and vFW. Above that is a management layer with an SDN controller, Security manager, Security analyser, and VNFM. At the top is a VPN orchestrator/NFVO. Enterprise sites 1 and 2 connect via Local CPEs to the SD-WAN core. Arrows indicate control and data flows between these components.](09955ff8214ffb6947951fc0f60eb6ab_img.jpg)
+
+The diagram illustrates the architecture for software-defined security in SD-WAN. At the top, a dashed box encloses the management and orchestration layer, which includes the VPN orchestrator/NFVO, SDN controller, Security manager, Security analyser, and VNFM. The VPN orchestrator/NFVO has bidirectional connections with the SDN controller, Security manager, Security analyser, and VNFM. The SDN controller has bidirectional connections with the Security manager and Security analyser. The Security manager and Security analyser have bidirectional connections with the VNFM. Below this management layer is the 'Security resource' block, which contains vSwitch, vIPS, and vFW. The SDN controller has a bidirectional connection to the vSwitch. The Security manager has a bidirectional connection to the vIPS. The Security analyser has a bidirectional connection to the vFW. The vSwitch, vIPS, and vFW are connected to the SD-WAN core. The SD-WAN core consists of three routers. The left router is connected to Enterprise site 1 via Local CPE 1. The right router is connected to Enterprise site 2 via Local CPE 2. The middle router is connected to the left and right routers. The SDN controller has a bidirectional connection to the left router. The Security manager has a bidirectional connection to the middle router. The Security analyser has a bidirectional connection to the right router. The VNFM has a bidirectional connection to the right router. The diagram is labeled X.1046(20)\_F09.
+
+Figure 9: Example of security service provision by software-defined security in SD-WAN. The diagram shows a central SD-WAN core with three routers. Above it is a 'Security resource' block containing vSwitch, vIPS, and vFW. Above that is a management layer with an SDN controller, Security manager, Security analyser, and VNFM. At the top is a VPN orchestrator/NFVO. Enterprise sites 1 and 2 connect via Local CPEs to the SD-WAN core. Arrows indicate control and data flows between these components.
+
+**Figure 9 – Example of security service provision by software-defined security in SD-WAN**
+
+The forwarding policy and security policy of a VPN service for an enterprise can be sent to the SDN controller and the security manager respectively. The SDN controller sends the forwarding rules to the forwarding functions such as customer premise equipment (CPE) and virtual switch (vSwitch). The security manager resolves the security policy, selects applicable security function(s)
+
+and configures related security policy in the selected security function(s). The security analyser analyses the security threats through analysing the security logs of the security functions and the network traffic. Then it provides security threat awareness to the enterprise. In this way, the software-defined security can provide security service to enterprises on demand.
+
+# Bibliography
+
+- [b-ITU-T X.1036] Recommendation ITU-T X.1036 (2007): *Framework for creation, storage, distribution and enforcement of policies for network security*.
+- [b-OASIS OpenC2-L] OASIS Open Command Open Command and Control (OpenC2) Language Specification Version 1.0.  
+<<https://docs.oasis-open.org/openc2/oc2ls/v1.0/cs01/oc2ls-v1.0-cs01.html>>
+- [b-OASIS OpenC2-H] OASIS Specification for Transfer of OpenC2 Messages via HTTPS Version 1.0.  
+<<https://docs.oasis-open.org/openc2/open-impl-https/v1.0/cs01/open-impl-https-v1.0-cs01.html>>
+- [b-OASIS OpenC2-P] OASIS Open Command and Control (OpenC2) Profile for Stateless Packet Filtering Version 1.0.  
+<<https://docs.oasis-open.org/openc2/open-impl-https/v1.0/cs01/open-impl-https-v1.0-cs01.html>>
+- [b-IETF RFC 3176] IETF RFC 3176 (2001), *sFlow: A Method for Monitoring Traffic in Switched and Routed Networks*.
+- [b-IETF RFC 3917] IETF RFC 3917 (2004), *Requirements for IP Flow Information Export (IPFIX)*.
+- [b-IETF RFC 5246] IETF RFC 5246 (2008), *The Transport Layer Security (TLS) Protocol Version 1.2*.
+- [b-IETF RFC 8329] IETF RFC 8329 (2018), *Framework for Interface to Network Security Functions*.
+- [b-ETSI NFV IFA 010] Network Functions Virtualisation (NFV) Release 3; *Management and Orchestration; Functional requirements specification*.  
+<[https://www.etsi.org/deliver/etsi\\_gs/NFV-IFA/001\\_099/010/03.04.01\\_60/gs\\_NFV-IFA010v030401p.pdf](https://www.etsi.org/deliver/etsi_gs/NFV-IFA/001_099/010/03.04.01_60/gs_NFV-IFA010v030401p.pdf)>
+- [b-ETSI NFV-SEC 003] ETSI GR NFV-SEC 003 (2016), *NFV Security; Security and Trust Guidance*.  
+<[https://www.etsi.org/deliver/etsi\\_gr/NFV-SEC/001\\_099/003/01.02.01\\_60/gr\\_NFV-SEC003v010201p.pdf](https://www.etsi.org/deliver/etsi_gr/NFV-SEC/001_099/003/01.02.01_60/gr_NFV-SEC003v010201p.pdf)>
+- [b-ETSI NFV 002] Network Functions Virtualisation (NFV) (2014); *Architectural Framework*.  
+<[https://www.etsi.org/deliver/etsi\\_gs/NFV-SEC/001\\_099/012/03.01.01\\_60/gs\\_NFV-SEC012v030101p.pdf](https://www.etsi.org/deliver/etsi_gs/NFV-SEC/001_099/012/03.01.01_60/gs_NFV-SEC012v030101p.pdf)>
+- [b-ETSI NFV 003] Network Functions Virtualisation (NFV) (2018); *Terminology for Main Concepts in NFV*  
+<[https://www.etsi.org/deliver/etsi\\_gs/NFV/001\\_099/003/01.04.01\\_60/gs\\_NFV003v010401p.pdf](https://www.etsi.org/deliver/etsi_gs/NFV/001_099/003/01.04.01_60/gs_NFV003v010401p.pdf)>
+- [b-ONF SDN White paper] *Software-Defined Networking: The New Norm for Networks* (2012)  
+<<https://www.techlib.com/el/view/shapcart/software-defined-networking-the-new-norm-for-networks>>
+- [b-RESTful] *RESTful Web Services - Introduction*  
+<<https://www.tutorialspoint.com/restful/restful-introduction.htm>>
+- [b-UNISAFE] Taejune Park, Yeonkeun Kim, Seungwon Shin; UNISAFE: *A Union of Security Actions for Software Switches*, ACM 2016, DOI: <<http://dx.doi.org/10.1145/2876019.2876025>>
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| Series F        | Non-telephone telecommunication services                                                                                                                  |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| <b>Series X</b> | <b>Data networks, open system communications and security</b>                                                                                             |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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@@ -0,0 +1,955 @@
+
+
+# Recommendation**ITU-T X.1095 (11/2023)**
+
+SERIES X: Data networks, open system communications  
+and security
+
+Information and network security – Telebiometrics
+
+---
+
+## **Entity authentication service for pet animals using telebiometrics**
+
+## ITU-T X-SERIES RECOMMENDATIONS
+
+## Data networks, open system communications and security
+
+|                                      |                      |
+|--------------------------------------|----------------------|
+| PUBLIC DATA NETWORKS                 | X.1-X.199            |
+| OPEN SYSTEMS INTERCONNECTION         | X.200-X.299          |
+| INTERWORKING BETWEEN NETWORKS        | X.300-X.399          |
+| MESSAGE HANDLING SYSTEMS             | X.400-X.499          |
+| DIRECTORY                            | X.500-X.599          |
+| OSI NETWORKING AND SYSTEM ASPECTS    | X.600-X.699          |
+| OSI MANAGEMENT                       | X.700-X.799          |
+| SECURITY                             | X.800-X.849          |
+| OSI APPLICATIONS                     | X.850-X.899          |
+| OPEN DISTRIBUTED PROCESSING          | X.900-X.999          |
+| INFORMATION AND NETWORK SECURITY     | X.1000-X.1099        |
+| General security aspects             | X.1000-X.1029        |
+| Network security                     | X.1030-X.1049        |
+| Security management                  | X.1050-X.1069        |
+| <b>Telebiometrics</b>                | <b>X.1080-X.1099</b> |
+| SECURE APPLICATIONS AND SERVICES (1) | X.1100-X.1199        |
+| CYBERSPACE SECURITY                  | X.1200-X.1299        |
+| SECURE APPLICATIONS AND SERVICES (2) | X.1300-X.1499        |
+| CYBERSECURITY INFORMATION EXCHANGE   | X.1500-X.1599        |
+| CLOUD COMPUTING SECURITY             | X.1600-X.1699        |
+| QUANTUM COMMUNICATION                | X.1700-X.1729        |
+| DATA SECURITY                        | X.1750-X.1799        |
+| IMT-2020 SECURITY                    | X.1800-X.1819        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T X.1095
+
+# Entity authentication service for pet animals using telebiometrics
+
+## Summary
+
+Recommendation ITU-T X.1095 defines an entity authentication infrastructure for pet animals using telebiometrics. It specifies multimodal telebiometrics, which uses nose patterns and faces of pet animals. This Recommendation is applicable in various pet animal services such as registration, insurance and e-health care for pet animals. Entity authentication for pet animals is always performed in a non-cooperative environment, therefore it is necessary to define criteria for acquiring suitable multimodal telebiometrics for pet entity authentication. There are also requirements for devices that acquire multimodal telebiometrics, and architecture in the operating platform for stable multimodal telebiometric applications for pet animals.
+
+This Recommendation specifies functional requirements for biometric capture devices and data acquisition of biometrics for pet entity authentication. A platform architecture, performance testing methodology and privacy issues are also defined.
+
+The following topics are addressed in the scope of this Recommendation:
+
+- Pet animals cover dogs and cats;
+- Multimodal telebiometrics cover nose patterns and faces;
+- Biometric capture devices cover digital cameras, mobile cameras, specific cameras such as infrared cameras, high-speed cameras and optical scanners.
+
+## History \*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T X.1095   | 2023-11-13 | 17          | 11.1002/1000/15708 |
+
+## Keywords
+
+Cat, dog, entity authentication, face, multimodal telebiometrics, nose pattern, pet animals, registration.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+### NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2024
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+# Table of Contents
+
+|    |                                                                                                                                | Page |
+|----|--------------------------------------------------------------------------------------------------------------------------------|------|
+| 1  | Scope .....                                                                                                                    | 1    |
+| 2  | References.....                                                                                                                | 1    |
+| 3  | Definitions .....                                                                                                              | 1    |
+|    | 3.1 Terms defined elsewhere.....                                                                                               | 1    |
+|    | 3.2 Terms defined in this Recommendation.....                                                                                  | 2    |
+| 4  | Abbreviations and acronyms .....                                                                                               | 2    |
+| 5  | Conventions .....                                                                                                              | 3    |
+| 6  | Prerequisites.....                                                                                                             | 3    |
+| 7  | Overview of multimodal telebiometrics for pet entity authentication.....                                                       | 3    |
+|    | 7.1 Types of multimodal telebiometrics.....                                                                                    | 3    |
+|    | 7.2 Characteristics of telebiometrics for pet entity authentication .....                                                      | 3    |
+| 8  | Requirements for biometric capture devices for pet entity authentication .....                                                 | 4    |
+|    | 8.1 Types of biometric capture devices.....                                                                                    | 4    |
+|    | 8.2 Functional requirements for biometric capture devices for pet animals .....                                                | 4    |
+|    | 8.3 Data interchange format for biometric capture devices .....                                                                | 5    |
+| 9  | Requirements for an architecture of the pet entity authentication platform .....                                               | 7    |
+|    | 9.1 Overview .....                                                                                                             | 7    |
+|    | 9.2 Functional requirements for pet entity authentication mechanism.....                                                       | 7    |
+|    | 9.3 Functional requirements for telebiometric transmission protocol.....                                                       | 8    |
+|    | 9.4 General requirements of testing DB for pet entity authentication.....                                                      | 8    |
+| 10 | Performance testing methodology for pet entity authentication mechanisms .....                                                 | 10   |
+|    | 10.1 General .....                                                                                                             | 10   |
+|    | 10.2 Technology evaluation procedures.....                                                                                     | 10   |
+|    | 10.3 Scenario evaluation procedures.....                                                                                       | 11   |
+| 11 | Personally identifiable information (PII) protection of entity authentication service for pet animals and their guardians..... | 12   |
+|    | 11.1 Personally identifiable information (PII) protection policy .....                                                         | 12   |
+|    | Appendix I – Use case for database construction scenario for pet entity authentication.....                                    | 14   |
+|    | I.1 Requirements for database construction for pet entity authentication .....                                                 | 14   |
+|    | I.2 Requirements for the database construction process.....                                                                    | 15   |
+|    | I.3 Metadata features.....                                                                                                     | 15   |
+|    | I.4 Rescue service for lost pets based on pet entity authentication using telebiometrics .....                                 | 16   |
+|    | Appendix II – Use case for telebiometric entity authentication model for pet animals.....                                      | 17   |
+|    | II.1 Requirements for an architecture of the pet entity authentication platform...                                             | 17   |
+|    | Bibliography.....                                                                                                              | 19   |
+
+
+
+# Recommendation ITU-T X.1095
+
+## Entity authentication service for pet animals using telebiometrics
+
+# 1 Scope
+
+This Recommendation specifies functional requirements for biometric capture devices and data acquisition of biometrics for pet entity authentication. A platform architecture, performance testing methodology and privacy issues are also defined.
+
+The following topics are addressed within the scope of this Recommendation:
+
+- Pet animals, referring dogs and cats;
+- Multimodal telebiometrics, referring to nose pattern and face;
+- Biometric capture devices, referring to digital cameras, mobile cameras, specific cameras such as infrared cameras, high-speed cameras and optical scanners.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+None.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 biometric capture device** [b-ISO/IEC 2382-37]: Device that collects a signal from a biometric characteristic and converts it to a captured biometric sample.
+
+**3.1.2 detection error trade-off (DET)** [b-ISO/IEC 19795-1]: Relationship between false-negative and false-positive errors of a binary classification system as the discrimination threshold varies.
+
+**3.1.3 digital camera** [b-ISO 29301]: Device that detects the image using a chip-arrayed image sensor, such as a charge-coupled device (CCD) or complementary metal-oxide semiconductor (CMOS), that converts a visual image to an electric signal.
+
+**3.1.4 equal error rate (EER)** [b-ISO/IEC 2382-37]: Value at which the FRR [false reject rate] and FAR [false accept rate] are equal.
+
+**3.1.5 false accept rate (FAR)** [b-ISO/IEC 2382-37]: Proportion of biometric transactions with false biometric claims erroneously accepted.
+
+**3.1.6 false reject rate (FRR)** [b-ISO/IEC 2382-37]: Proportion of verification transactions with true biometric claims erroneously rejected.
+
+**3.1.7 failure to enrol (FTE)** [b-ISO/IEC 2382-37]: Failure to create and store a biometric enrolment data record for an eligible biometric capture subject in accordance with a biometric enrolment policy.
+
+**3.1.8 failure to acquire (FTA)** [b-ISO/IEC 2382-37]: Failure to accept for subsequent comparison the biometric sample of the biometric characteristic of interest output from the biometric capture process.
+
+**3.1.9 false match** [b-ISO/IEC 2382-37]: Comparison decision of a match for a biometric probe and a biometric reference that are from different biometric capture subjects.
+
+**3.1.10 false non-match** [b-ISO/IEC 2382-37]: Comparison decision of a non-match for a biometric probe and a biometric reference that are from the same biometric capture subject and of the same biometric characteristic.
+
+**3.1.11 optical image stabilization** [b-ISO 20954-1]: Function that compensates for image displacement on the focal plane due to movement of a handheld camera by moving a part or whole of the optical system and/or image sensor, based on a means of camera movement detection.
+
+**3.1.12 optical scanner** [b-ISO 6196-7]: A scanner that uses light for examining patterns.
+
+**3.1.13 scenario evaluation** [b-ISO/IEC 2382-37]: Evaluation that measures end-to-end system performance in a prototype or simulated application with a test crew.
+
+**3.1.14 technology evaluation** [b-ISO/IEC 2382-37]: Offline evaluation of one or more algorithms for the same biometric modality using a pre-existing or especially-collected corpus of samples.
+
+## **3.2 Terms defined in this Recommendation**
+
+This Recommendation defines the following terms:
+
+**3.2.1 guardian:** Person that takes care of pet animals in their homes or in shelters.
+
+**3.2.2 mobile camera:** A camera that is integrated into a smartphone or mobile device.
+
+**3.2.3 nose pattern:** Biometric pattern of wrinkles on the nose of pet animals.
+
+**3.2.4 pan:** The degree of horizontal movement of a camera head without changing the position of the camera.
+
+**3.2.5 specific camera:** A camera that is designed for a specific purpose or use, such as an infrared camera or high-speed camera.
+
+**3.2.6 tilt:** The degree of vertical movement of a camera head without changing the position of the camera.
+
+# **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+CCD Charge-Coupled Device
+
+CMOS Complementary Metal-Oxide Semiconductor
+
+DB Database
+
+FAR False Accept Rate
+
+FRR False Error Rate
+
+FTA Failure To Acquire
+
+FTE Failure To Enrol
+
+OIS Optical Image Stabilization
+
+PII Personal Identifiable Information
+
+ROI Region Of Interest
+
+# 5 Conventions
+
+None.
+
+# 6 Prerequisites
+
+None.
+
+# 7 Overview of multimodal telebiometrics for pet entity authentication
+
+## 7.1 Types of multimodal telebiometrics
+
+### 7.1.1 Nose pattern
+
+The nose pattern is a biometric marker that is unique in pet animals with wrinkles on the nose. The nose pattern comprises ridges and troughs. The ridges are a flattened area placed relatively high, and the troughs are an elongated and sunken area placed relatively low. The ridges and troughs are mapped as a polygonal pattern, and this complex pattern is a biometric marker that is unique for each pet animal.
+
+### 7.1.2 Face
+
+The face, with its geometric features between the eyes, nose and muzzle represents a unique biometric marker for the identity of pet animals.
+
+## 7.2 Characteristics of telebiometrics for pet entity authentication
+
+### 7.2.1 Nose pattern
+
+Figure 1 shows an example of the characteristics of the nose pattern of two pet animals.
+
+![Figure 1: Characteristics of the nose pattern of pet animals. The figure consists of two side-by-side photographs of pet animal noses. Each photograph has a red rectangular box highlighting the area between the nostrils. A red arrow points from this box to a magnified inset showing the complex, wrinkled skin pattern of the nose. Yellow circles highlight the nostrils, and a green line points to the philtrum. Labels 'Nostril' and 'Philtrum' are present for both images. The right image is labeled 'X.1095(23)'.](af8f80bac7328747fbc93c2eb86f5be9_img.jpg)
+
+The figure shows two close-up photographs of pet animal noses. In each photo, a red rectangle highlights the area between the nostrils. A red arrow points from this rectangle to a magnified inset showing the complex, wrinkled skin pattern of the nose. Yellow circles highlight the nostrils, and a green line points to the philtrum. Labels 'Nostril' and 'Philtrum' are present for both images. The right image is labeled 'X.1095(23)'.
+
+Figure 1: Characteristics of the nose pattern of pet animals. The figure consists of two side-by-side photographs of pet animal noses. Each photograph has a red rectangular box highlighting the area between the nostrils. A red arrow points from this box to a magnified inset showing the complex, wrinkled skin pattern of the nose. Yellow circles highlight the nostrils, and a green line points to the philtrum. Labels 'Nostril' and 'Philtrum' are present for both images. The right image is labeled 'X.1095(23)'.
+
+**Figure 1 – Characteristics of the nose pattern of pet animals**
+
+The nose pattern is mainly found between the nostrils of the pet animals and has a very complex skin folding pattern. The complex pattern represents the unique identity of each pet animal.
+
+### 7.2.2 Face
+
+Figure 2 shows an example of the characteristics of the face of pet animals.
+
+![Figure 2 shows four images of pet animals (two dogs and two cats) with red dashed boxes highlighting their eyes, nose, and muzzle, illustrating facial features used for biometric capture.](e7cb11f042fc58088dff4b6d9306845e_img.jpg)
+
+Figure 2 consists of four square images arranged in a 2x2 grid. The top-left image shows a white puppy lying down with red dashed boxes around its eyes, nose, and muzzle. The top-right image shows a grey Weimaraner dog's head against a black background with red dashed boxes around its eyes, nose, and muzzle. The bottom-left image shows a tabby cat's face with red dashed boxes around its eyes, nose, and muzzle. The bottom-right image shows a light brown cat's face with red dashed boxes around its eyes, nose, and muzzle. A small text label 'X.1095(23)' is located at the bottom right of the grid.
+
+Figure 2 shows four images of pet animals (two dogs and two cats) with red dashed boxes highlighting their eyes, nose, and muzzle, illustrating facial features used for biometric capture.
+
+**Figure 2 – Characteristics of the face of pet animals**
+
+The face has unique geometric features for each pet animal as it does in humans, and it these can be extracted by detecting the eyes, nose and muzzle of the pet animals.
+
+# **8 Requirements for biometric capture devices for pet entity authentication**
+
+## **8.1 Types of biometric capture devices**
+
+In general, sensors for detecting the biometrics of pet animals at a distance can be classified into three types of image recording devices such as mobile cameras, digital cameras and specific cameras. Optical scanners can be a sensor for detecting biometrics through contact.
+
+## **8.2 Functional requirements for biometric capture devices for pet animals**
+
+Biometric capture devices should be able to cope with the unexpected movements of pet animals. Sensors for detecting biometrics at a distance should meet the minimum requirements for image resolution, shutter speed, ISO and aperture. Sensors for detecting biometrics through contact should position the biometrics of the pet animals on a prism area of the optical scanner. The minimum requirements can be determined by the quality of the region of interest (ROI) images containing the biometrics of the pet animals. The ROI images of the nose pattern should contain more than 60% of biometrics and the ratio of the biometrics should be measured by the number of pixels within the images.
+
+**Table 1 – Minimum requirements for sensors used at a distance**
+
+| <b>S No.</b> | <b>Items</b>            | <b>Requirements</b>               |
+|--------------|-------------------------|-----------------------------------|
+| 1            | Pixels                  | 5 megapixels (MP)                 |
+| 2            | Sensor size             | 1/3 inch                          |
+| 3            | Aperture                | f/1.8                             |
+| 4            | Resolution              | 1 080 × 1 080 pixels              |
+| 5            | Shutter speed (indoor)  | 1/1 000th of a second to 1 second |
+| 6            | Shutter speed (outdoor) | 1/500th of a second to 1 second   |
+| 7            | ISO                     | 200 to 400                        |
+
+**Table 2 – Minimum requirements for sensors using in contact**
+
+| S No. | Items                   | Requirements             |
+|-------|-------------------------|--------------------------|
+| 1     | Pixels                  | 2 megapixels (MP)        |
+| 2     | Resolution              | 500 DPI                  |
+| 3     | Frames per second (fps) | 10 fps                   |
+| 4     | Image format            | RAW, BMP, WSQ, JPEG 2000 |
+
+**Table 3 – Minimum requirements for ROI for nose pattern**
+
+| S No. | Items                        | Requirements     |
+|-------|------------------------------|------------------|
+| 1     | Size of ROI                  | 256 × 256 pixels |
+| 2     | Ratio of biometrics (in ROI) | 60%              |
+
+![Diagram illustrating the Region of Interest (ROI) for nose pattern biometrics in a pet animal's face. The main image shows a pet's face with a dashed box around the nose area. An inset shows a magnified view of the nose area, labeled 'ROI (Region of interest)', with a blue shaded region labeled 'Biometrics'.](d29cfbf30a471dc06a78be27f86bd1cf_img.jpg)
+
+The diagram illustrates the process of identifying a Region of Interest (ROI) for biometric analysis on a pet's face. On the left, a line drawing of a pet's head is shown with a dashed rectangular box highlighting the nose area. A line connects this box to a magnified inset on the right. The inset shows a close-up of the nose, with a blue shaded area labeled 'Biometrics' and the entire inset area labeled 'ROI (Region of interest)'.
+
+X.1095(23)
+
+Diagram illustrating the Region of Interest (ROI) for nose pattern biometrics in a pet animal's face. The main image shows a pet's face with a dashed box around the nose area. An inset shows a magnified view of the nose area, labeled 'ROI (Region of interest)', with a blue shaded region labeled 'Biometrics'.
+
+**Figure 3 – An example of the ROI image for the nose pattern of pet animals**
+
+## **8.3 Data interchange format for biometric capture devices**
+
+For pet entity authentication using biometrics, the procedures shown in Figure 4 must be followed. The procedure has a client-server structure based on the sensors and can be either separable or integral, depending on whether or not there is a communication unit.
+
+![Figure 4: Biometric data flow for biometric capture devices based on a client-server structure. The diagram shows three main components: Biometric capture device, Client, and Server. The Biometric capture device contains 'Camera/sensor activation' and 'Data acquisition'. The Client contains 'Data request', 'Biometrics detection', 'Feature extraction', 'Quality assessment', and 'Verification or identification'. The Server contains 'Compare with registered template' and 'Matching result'. Arrows show the flow: 'Data request' from Client to Biometric capture device; 'Data acquisition' from Biometric capture device to Client; 'Biometrics detection' from Client to Client; 'Feature extraction' from Client to Client; 'Quality assessment' from Client to Client; 'Biometric template' from Client to Server; 'Compare with registered template' from Server to Server; 'Matching result' from Server to Client; and 'Verification or identification' from Client to Client.](d4af765160d04ecef538e5066006dc77_img.jpg)
+
+```
+
+graph LR
+    subgraph Biometric_capture_device [Biometric capture device]
+        A[Camera/sensor activation] --> B[Data acquisition]
+    end
+    subgraph Client
+        C[Data request] --> D[Biometrics detection]
+        D --> E[Feature extraction]
+        E --> F[Quality assessment]
+        F --> G[Verification or identification]
+    end
+    subgraph Server
+        H[Compare with registered template] --> I[Matching result]
+    end
+    C --> A
+    B --> D
+    D --> E
+    E --> F
+    F -- "Biometric template" --> H
+    H -- "Matching result" --> G
+    
+```
+
+Figure 4: Biometric data flow for biometric capture devices based on a client-server structure. The diagram shows three main components: Biometric capture device, Client, and Server. The Biometric capture device contains 'Camera/sensor activation' and 'Data acquisition'. The Client contains 'Data request', 'Biometrics detection', 'Feature extraction', 'Quality assessment', and 'Verification or identification'. The Server contains 'Compare with registered template' and 'Matching result'. Arrows show the flow: 'Data request' from Client to Biometric capture device; 'Data acquisition' from Biometric capture device to Client; 'Biometrics detection' from Client to Client; 'Feature extraction' from Client to Client; 'Quality assessment' from Client to Client; 'Biometric template' from Client to Server; 'Compare with registered template' from Server to Server; 'Matching result' from Server to Client; and 'Verification or identification' from Client to Client.
+
+**Figure 4 – Biometric data flow for biometric capture devices based on a client-server structure**
+
+Figure 5 describes the data interchange format for biometric capture devices. This format consists of a file header representing basic information, biometric raw and feature data. A security block can be configured as necessary.
+
+![](27b06ec9f42b5d727a2630f61a5f1861_img.jpg)
+
+|             |                    |                        |                           |
+|-------------|--------------------|------------------------|---------------------------|
+| File header | Biometric raw data | Biometric feature data | Security block (Optional) |
+|-------------|--------------------|------------------------|---------------------------|
+
+X.1095(23)
+
+**Figure 5 – Data interchange format for biometric capture devices**
+
+### 8.3.1 File header
+
+The file header format consists of basic information that summarizes the characteristics of the biometric raw and feature data, including sensor, time and measurement information.
+
+### 8.3.2 Biometric raw data
+
+The biometric raw data format consists of a length header indicating the length of the raw data, signal quality and raw data array measured from the biometric capture devices.
+
+### 8.3.3 Biometric feature data
+
+The biometric feature data format consists of a length header indicating the length of the feature data and binarized data which implements unique features of each pet animal extracted from the biometric raw data.
+
+### 8.3.4 Security block
+
+The security block is optional and contains additional security parameters. It indicates whether or not all biometric data are signed and whether the raw or feature data are encrypted.
+
+# 9 Requirements for an architecture of the pet entity authentication platform
+
+## 9.1 Overview
+
+The pet entity authentication model using telebiometrics comprises data acquisition, data transmission and biometric authentication processes. Figure 6 shows an entity authentication model using a mobile camera. The main application models for the pet entity authentication platform include rescuing abandoned animals, pet insurance, pet health care and pet travelling.
+
+![Figure 6: Telebiometric authentication model for pet entity authentication. The diagram shows a flow from Pet animals to Capture, then to Feature extraction (Face and Nose pattern), followed by Normalization (Face and Nose pattern), then Data storage (Public or private network), and finally Application (Pet-tech services). The process is divided into three main stages: Data acquisition, Data transmission, and Biometric authentication.](ff0952ef692c9d960ce5f6708bcc9711_img.jpg)
+
+The diagram illustrates the telebiometric authentication model for pet entity authentication. It is divided into three main stages: Data acquisition, Data transmission, and Biometric authentication.
+
+- Data acquisition:** This stage includes 'Pet animals' (images of a white dog and a brown dog) and 'Capture' (images of the same dogs with green bounding boxes around their faces and noses).
+- Data transmission:** This stage includes 'Feature extraction' (Biometrics: Face and Nose pattern) and 'Normalization' (Biometrics: Face and Nose pattern).
+- Biometric authentication:** This stage includes 'Data storage' (Public or private network) and 'Application' (Pet-tech services: Rescue abandoned animal, pet insurance, Pet healthcare, pet travelling).
+
+The process flow is as follows: Pet animals → Capture → Feature extraction → Normalization → Data storage → Application. The Data acquisition stage covers the first two steps, Data transmission covers the next two, and Biometric authentication covers the final two.
+
+X.1095(23)
+
+Figure 6: Telebiometric authentication model for pet entity authentication. The diagram shows a flow from Pet animals to Capture, then to Feature extraction (Face and Nose pattern), followed by Normalization (Face and Nose pattern), then Data storage (Public or private network), and finally Application (Pet-tech services). The process is divided into three main stages: Data acquisition, Data transmission, and Biometric authentication.
+
+Figure 6 – Telebiometric authentication model for pet entity authentication
+
+## 9.2 Functional requirements for pet entity authentication mechanism
+
+### 9.2.1 Data acquisition and pre-processing
+
+The biometrics of pet animals are gathered from the biometric capture devices and are pre-processed for signal optimization before the feature is extracted. Biometric raw data are pre-processed through analogue or digital filters. In the case of using cameras as the biometric capture device, filters should be optimized to reduce noise from unconstrained illumination and motion of the pet animals. In the case of using an optical scanner as the biometric capture device, filters should be optimized to reduce noise from unconstrained motion and moisture on the nose of pet animals. If the quality of the filtered biometric raw data is not enough to perform entity authentication for each pet animal, the gathered data should be discarded and the acquisition process should be repeated.
+
+![Figure 7: Data acquisition and pre-processing model for pet entity authentication mechanism. The diagram shows a flow from Data acquisition (Cameras and Optical scanners) to Noise reduction, then to Biometrics, followed by Quality assessment, Assessment score, and finally Feature extraction. A feedback loop labeled 'No' returns from the Assessment score to the Data acquisition stage.](4636adff5682a064f0ae5f13a1d464a6_img.jpg)
+
+The diagram illustrates the data acquisition and pre-processing model for pet entity authentication mechanism. It shows a flow from Data acquisition to Noise reduction, then to Biometrics, followed by Quality assessment, Assessment score, and finally Feature extraction. A feedback loop labeled 'No' returns from the Assessment score to the Data acquisition stage.
+
+X.1095(23)
+
+Figure 7: Data acquisition and pre-processing model for pet entity authentication mechanism. The diagram shows a flow from Data acquisition (Cameras and Optical scanners) to Noise reduction, then to Biometrics, followed by Quality assessment, Assessment score, and finally Feature extraction. A feedback loop labeled 'No' returns from the Assessment score to the Data acquisition stage.
+
+Figure 7 – Data acquisition and pre-processing model for pet entity authentication mechanism
+
+### 9.2.2 Feature extraction and registration in a biometric database
+
+Individual characteristic feature points are extracted from the biometrics. An algorithm extracts biometric features that minimize intra-individual variability and maximize inter-individual variability for each biometric characteristic. The extracted biometric features are then registered in a database
+
+(DB). If there is an attempt to authenticate the same pet animal later, the biometric feature dataset is loaded onto the DB through the ID, and the pet animal is authenticated through a comparison of the feature points.
+
+### 9.2.3 Matching algorithm
+
+In 1:1 verification, registered biometric feature data are compared one-to-one with the feature data of the pet animal for which authentication is being attempted. When authentication is attempted, the features extracted from the measured biometrics are compared with the registered features on the DB. The ID of the pet animal is presented and the registered biometric feature data from the DB are loaded as shown in Figure 8. A similarity score between features is calculated and the results are passed if the score exceeds a threshold level. The similarity score should be calculated through objective mathematical calculations, such as the Euclidean distance or the Mahalanobis distance.
+
+In 1:N identification, the data of the pet animal to be identified are compared with all the data on the DB. Since the data comparison is performed on all the registered data, the trials of the matching process increase exponentially depending on the number of the registered pet animals. In this analysis process, it is preferable to use a majority of the agreement analysis methods to increase the reliability of the agreement calculation, and a process of comprehensively evaluating the results of the calculation is also required. A pet animal that has the highest degree of agreement is judged to be the same entity as the requester of the identification and the result should be provided.
+
+![Flowchart of the 1:1 verification process for pet entity authentication. The process starts with 'ID and password' input to the 'Registered biometrics DB'. This leads to 'Retrieved biometrics'. Simultaneously, 'Input biometric' is processed into 'Face' and 'Nose pattern' features. These are compared with the 'Retrieved biometrics' in 'Analysis 1' and 'Analysis 2'. The results from both analyses feed into a 'Matching score' block, which outputs a score '0 ~ 100'. This score leads to a 'Decision' block, which finally outputs 'Yes/No'.](bd671b21db63e6fdb2196e9b18502aac_img.jpg)
+
+```
+
+graph LR
+    ID[ID and password] --> DB[(Registered biometrics DB)]
+    DB --> Retrieved[Retrieved biometrics]
+    Input[Input biometric] --> Face[Face]
+    Input --> Nose[Nose pattern]
+    Retrieved -- Face --> Analysis1[Analysis 1]
+    Retrieved -- Nose pattern --> Analysis2[Analysis 2]
+    Face --> Analysis1
+    Nose --> Analysis2
+    Analysis1 --> Score[Matching score]
+    Analysis2 --> Score
+    Score --> Decision[Decision]
+    Decision --> Result[Yes/No]
+    
+```
+
+X.1095(23)
+
+Flowchart of the 1:1 verification process for pet entity authentication. The process starts with 'ID and password' input to the 'Registered biometrics DB'. This leads to 'Retrieved biometrics'. Simultaneously, 'Input biometric' is processed into 'Face' and 'Nose pattern' features. These are compared with the 'Retrieved biometrics' in 'Analysis 1' and 'Analysis 2'. The results from both analyses feed into a 'Matching score' block, which outputs a score '0 ~ 100'. This score leads to a 'Decision' block, which finally outputs 'Yes/No'.
+
+**Figure 8 – 1:1 verification process for pet entity authentication**
+
+## 9.3 Functional requirements for telebiometric transmission protocol
+
+This clause defines the functional requirements for a telebiometric transmission protocol. Transferred biometric data must demonstrate a certain measure of compliance, interoperability and security. A telebiometric transmission protocol is an application protocol and is implemented in combination with standards-based communication protocols whether wired or wireless.
+
+## 9.4 General requirements of testing DB for pet entity authentication
+
+### 9.4.1 Data acquisition requirement for testing DB
+
+Data acquisition is the most crucial point due to an accuracy issue in entity authentication mechanisms. It is also important to consider the data acquisition environments and uncooperative characteristics of pet animals.
+
+Biometric data of the pet animals can be acquired with bias due to illuminating lights and exposure to biometric capture devices. Therefore, it is needed to acquire biometric data on pet animals in a controlled environment. To manage objective criteria on performance tests, the specification of several conditions for acquisition environments should be followed.
+
+Pet animals present uncooperative biometric capture subjects. To acquire appropriate images for the telebiometrics application of pet animals, a process that cleans parts of target biometrics is needed. To construct testing DB, the acquisition process can be performed multiple times.
+
+### 9.4.2 Procedure and method for the construction of testing DB
+
+Acquisition of telebiometrics should proceed in a relaxed environment with pet animals to avoid inducing unexpected actions. The environment can be set up with the help of a guardian, vet or an animal trainer. In the case of using cameras, it is recommended to proceed with acquisition in an indoor environment where a specific level of illumination can be maintained.
+
+### 9.4.3 Metadata features of testing DB
+
+Telebiometrics database for pet entity authentication comprises a common environment, device and characteristic metadata.
+
+**Table 4 – Common metadata of testing DB**
+
+| Class   | Features        | Meaning |
+|---------|-----------------|---------|
+| DB_Info | Country         |         |
+|         | City            |         |
+|         | Supplier        |         |
+|         | RegisterDate    |         |
+|         | RevisionDate    |         |
+|         | RevisionHistory |         |
+|         | Version         |         |
+
+**Table 5 – Environment and device metadata of testing DB**
+
+| Class            | Features            | Meaning |
+|------------------|---------------------|---------|
+| Environment_Info | ExperimentCondition | Lux     |
+| Device_Info      | DeviceType          |         |
+|                  | MaxResolution       |         |
+
+**Table 6 – Characteristic metadata of testing DB**
+
+| Class           | Features        | Meaning            |
+|-----------------|-----------------|--------------------|
+| File_Info       | FileFormat      |                    |
+|                 | FileName        |                    |
+|                 | DirectoryPath   |                    |
+|                 | FileSize        |                    |
+| Biometrics_Info | BiometricType   | Nose pattern, face |
+|                 | RawData         | Image or video     |
+|                 | ImageResolution |                    |
+| Subject_Info    | BirthDate       |                    |
+|                 | Gender          |                    |
+|                 | Breed           |                    |
+
+**Table 6 – Characteristic metadata of testing DB**
+
+| Class              | Features      | Meaning |
+|--------------------|---------------|---------|
+| Guardian_Info      | GuardianID    |         |
+| Miscellaneous_Info | OrderOfRepeat |         |
+|                    | Comment       |         |
+
+### 9.4.4 Data interchange formats for testing DB
+
+Telebiometrics of pet animals and related information should be stored in a specific DB through an encryption and compression process on a server. The compressed information is only accessible to designated persons who proceed with related projects.
+
+# 10 Performance testing methodology for pet entity authentication mechanisms
+
+## 10.1 General
+
+This clause defines guidelines for performance testing methodology based on technology and scenario evaluations. The main performance evaluation criteria are failure to enrol (FTE), failure to acquire (FTA), false reject rate (FRR), false accept rate (FAR), equal error rate (EER), and decision-error trade-off (DET) plots. The technology evaluation of the telebiometric authentication algorithm is an offline evaluation that repeatedly evaluates the recognition performance of the algorithm together with its processing speed, targeting an evaluation DB composed of biometric sample data collected in advance and a standardized DB. The performance of various algorithms can be compared with this evaluation method.
+
+## 10.2 Technology evaluation procedures
+
+### 10.2.1 Construction of the testing DB
+
+In technology evaluation, the testing DB should meet the minimum requirements listed in Table 7. The testing DB should include at least 500 subjects, 2 to 20 biometrics per subject, over two acquisition environments, and a total of 1 000 to 10 000 biometrics to cover a diverse range of breeds and ages of pet animals. Especially, the acquisition environment should consider the presence of the guardian, dog trainer or handler during the acquisition process to prevent accidents such as dog bites. Also, movements of the pet animals, out-of-focus biometric capture devices and moisture on biometrics should be controlled to appropriate levels.
+
+**Table 7 – Minimum requirements for testing DB**
+
+| Class                                                                         | Requirements                  |
+|-------------------------------------------------------------------------------|-------------------------------|
+| Number of subjects ( $N$ )                                                    | 500                           |
+| Number of breeds                                                              | 10                            |
+| Biometrics per subject ( $M$ )                                                | 2 to 20                       |
+| Number of acquisition environment                                             | 2                             |
+| Resolution                                                                    | 1 080 × 1 080 pixels          |
+| Size of ROI                                                                   | 256 × 256 pixels              |
+| Ratio of biometrics (in ROI)                                                  | 60%                           |
+| Minimum transactions on comparison decisions with the same biometric subjects | 500 ( $= {}_M C_2 \times N$ ) |
+
+**Table 7 – Minimum requirements for testing DB**
+
+| Class                                                                          | Requirements                        |
+|--------------------------------------------------------------------------------|-------------------------------------|
+| Minimum transactions on comparison decisions with different biometric subjects | 499,500 ( $= {}_n C_2 \times M^2$ ) |
+
+### 10.2.2 Sample quality test
+
+The testing DB should reflect the variability of the pet animals, and the variability should be constrained within a specific range to analyse the competitiveness of the performance evaluation. To ensure that the testing DB is constructed in a suitable condition to perform evaluation, a sample quality test of the DB should be performed.
+
+### 10.2.3 Technology test
+
+The process of technology test is composed of two steps: the preparation step and the evaluation step. The preparation step is processed as follows:
+
+- 1) Contact and provide a brief introduction of the evaluation environment.
+- 2) Prepare documents that describe detailed contracts, outcomes and evaluation processes.
+- 3) Share a sample DB that meets the minimum requirements of a testing DB.
+- 4) Perform testing in advance on a small scale using the sample DB.
+
+The evaluation step is processed as follows:
+
+- 1) Perform testing with a standardized DB.
+- 2) Analyse the results of the performance test and report the results.
+
+### 10.2.4 Analysis tests and reporting results
+
+The analysis and reporting procedure should be carried out as follows:
+
+- 1) Description of the technology used.
+- 2) Introduction of evaluation environments and criteria.
+- 3) Specification of the testing DB used.
+- 4) Evaluation of the quality of the testing DB.
+- 5) Procedure for testing performance evaluation.
+
+## 10.3 Scenario evaluation procedures
+
+### 10.3.1 Planning the evaluation
+
+Before conducting the scenario evaluation, the following should be prepared: the testing scenario, evaluation metrics, environments, testing algorithms and participants. The items listed in Table 8 should also be checked in advance.
+
+**Table 8 – Scenario test checklist**
+
+| Items             | Description                                                                                                                                              |
+|-------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Scenario features | Definition of application: Objective of the evaluation and scenario<br>Evaluation metrics: FAR, FRR, etc.<br>Environment and platform: Indoor or outdoor |
+| Evaluation policy | Policy related to the whole evaluation process                                                                                                           |
+| Level of trials   | Maximum and minimum levels of registration and authentication trials                                                                                     |
+
+**Table 8 – Scenario test checklist**
+
+|                                |                                                                                |
+|--------------------------------|--------------------------------------------------------------------------------|
+| Number of repeats              | The number of participants needed to visit the platform                        |
+| Minimum number of participants | Calculation based on the rule of 3<br>Estimates with FAR<br>Estimates with FRR |
+| Recording method               | Method to record the results of registration and authentication                |
+
+### 10.3.2 Scenario test
+
+Participants of the scenario test should register the biometrics for the first time on enrolment.  $N$  stands for the total visits of the participants. If registration fails for some participants, these participants can only take part in the imposter matching part of the test.
+
+![Flowchart of the general protocol of the scenario test. The process starts with 'Start', followed by 'Enrollment quality test' (labeled as 'First visit'). A decision diamond 'Success' follows. If 'No', it loops back to 'Enrollment quality test'. If 'Yes', it proceeds to 'Genuine matching' and 'Imposter matching' (grouped as '(N-1) visits'). A decision diamond 'Number of visits > N' follows. If 'No', it loops back to 'Genuine matching'. If 'Yes', it proceeds to 'Finish'. The reference X.1095(23) is noted at the bottom right.](9b9d2abd741ed4bafe7f78f89961c663_img.jpg)
+
+```
+
+graph LR
+    Start([Start]) --> Enrollment[Enrollment quality test]
+    Enrollment --> Success{Success}
+    Success -- No --> Enrollment
+    Success -- Yes --> Genuine[Genuine matching]
+    Genuine --> Imposter[Imposter matching]
+    Imposter --> Visits{Number of visits > N}
+    Visits -- No --> Genuine
+    Visits -- Yes --> Finish([Finish])
+    subgraph First_Visit [First visit]
+        Enrollment
+    end
+    subgraph N_minus_1_visits [(N-1) visits]
+        Genuine
+        Imposter
+    end
+    
+```
+
+X.1095(23)
+
+Flowchart of the general protocol of the scenario test. The process starts with 'Start', followed by 'Enrollment quality test' (labeled as 'First visit'). A decision diamond 'Success' follows. If 'No', it loops back to 'Enrollment quality test'. If 'Yes', it proceeds to 'Genuine matching' and 'Imposter matching' (grouped as '(N-1) visits'). A decision diamond 'Number of visits > N' follows. If 'No', it loops back to 'Genuine matching'. If 'Yes', it proceeds to 'Finish'. The reference X.1095(23) is noted at the bottom right.
+
+**Figure 9 – General protocol of the scenario test**
+
+### 10.3.3 Analysis tests and reporting results
+
+The reporting of scenario evaluation results comprises a summary, planning, procedure, data log, data analysis, data storage and the results of the evaluation.
+
+- 1) Summary: summary of information about the participants, evaluation results and so on.
+- 2) Scenario: description of the overall settings of the evaluation such as the objectives, metrics and environments.
+- 3) Planning: a detailed explanation of the evaluation plan.
+- 4) Procedure: description of the process of the initial contacts to the end of the evaluation.
+- 5) Data log: list of participants, results of registration and authentication.
+- 6) Data analysis: report of the results of the main-metrics and submetrics.
+- 7) Data storage: explanation of the method of data storage and space.
+- 8) Result of evaluation: table of each metric and conclusion on the testing algorithm.
+
+# 11 Personally identifiable information (PII) protection of entity authentication service for pet animals and their guardians
+
+## 11.1 Personally identifiable information (PII) protection policy
+
+A personally identifiable information (PII) protection policy is required when the telebiometric mechanism is applied to the entity authentication platform to minimize the risk of leaking personal information about the guardians of pet animals.
+
+### 11.1.1 Separation of DB
+
+To protect the personal information of guardians from outside attacks using the pet animal DB, it is required to separate the guardian DB from the pet animal DB. A guardian ID should be separated logically and physically from the biometrics of pet animals. In this case, a common identifier that can
+
+recognize both the guardian and the pet animal is needed. The common identifier should satisfy the security requirements as follows:
+
+- 1) Extraction of the guardian ID and biometrics of pet animals should be prohibited by only using the common identifier.
+- 2) If a certain DB is being attacked and modified illegally, managers of each DB should be able to notice and report it.
+- 3) If one manager attempts to modify the contents of a DB with a private key, the other manager should be able to notice the change.
+
+### **11.1.2 Guardian information**
+
+Personal information contained in the guardian information should be protected. Examples of the personal information of a guardian are name, phone number, birth date, address, sentence, voice and media. When a manager, who operates the entity authentication services for pet animals using telebiometrics, tries to collect personal information from a guardian, the following policy must be secured.
+
+- 1) Identifier of the guardian should be properly used and be informed about their usage in advance.
+- 2) Depending on the restriction regulation of data collection, the manager needs to be cautious not to collect data that is not necessary.
+- 3) If the manager has to connect to the personal information of each guardian, each guardian should receive a request for an agreement from the manager on using their information elsewhere.
+
+# Appendix I
+
+## Use case for database construction scenario for pet entity authentication
+
+(This appendix does not form an integral part of this Recommendation.)
+
+## I.1 Requirements for database construction for pet entity authentication
+
+### I.1.1 Data acquisition environment
+
+To execute objective performance tests, various types of environmental parameters should be considered. This scenario describes the types of places, illumination and camera angle for the biometric capture devices used in database construction. Only the nose pattern is obtained as biometrics data.
+
+The setting can be indoor or outdoor. Illumination can be set in various directions, and the camera angle can be set in a horizontal and vertical position along the frontal face of the pet animal.
+
+![Figure I.1: Three panels showing a dog's head with different illumination lamp configurations. The first panel shows a single yellow lamp on the left and two grey lamps above. The second panel shows three yellow lamps in a row above. The third panel shows two grey lamps above and one yellow lamp on the right.](1fd4fda95d22e337df091dfa8fa80f90_img.jpg)
+
+Figure I.1: Three panels showing a dog's head with different illumination lamp configurations. The first panel shows a single yellow lamp on the left and two grey lamps above. The second panel shows three yellow lamps in a row above. The third panel shows two grey lamps above and one yellow lamp on the right.
+
+Figure I.1 – Example of positioning illumination lamps in database construction
+
+![Figure I.2: Two diagrams illustrating biometric capture device positioning. The left diagram shows a dog's head with dashed lines representing camera fields of view from a vertical array of devices, labeled with 'd' and 't'. The right diagram shows a dog's head with a grid of cameras and light beams directed at its nose.](27f76d622d558d3895b67244855902b7_img.jpg)
+
+Figure I.2: Two diagrams illustrating biometric capture device positioning. The left diagram shows a dog's head with dashed lines representing camera fields of view from a vertical array of devices, labeled with 'd' and 't'. The right diagram shows a dog's head with a grid of cameras and light beams directed at its nose.
+
+Figure I.2 – Example of positioning biometric capture devices at various angle
+
+### I.1.2 Biometric capture devices
+
+To minimize an unexpected bias in image quality that can occur with cameras, it is recommended to use cameras equipped with optical image stabilization (OIS) and USB 3.0 systems. The number of cameras is calculated by the parameters of environmental conditions containing the illumination and camera angles.
+
+**Table I.1 – Example of calculating the number of biometric capture devices**
+
+| <b>Devices</b> | <b>The number of pan parameters<br/>(A)</b> | <b>The number of tilt parameters<br/>(B)</b> | <b>The number of devices<br/>(C = A*B)</b> |
+|----------------|---------------------------------------------|----------------------------------------------|--------------------------------------------|
+| Mobile camera  | 3                                           | 3                                            | 9                                          |
+
+## **I.2 Requirements for the database construction process**
+
+### **I.2.1 Preparation process**
+
+Adequate places for database construction are places where pet animals are numerous, such as pet playgrounds, pet parks, animal shelters and rabies vaccination events. It is required to prepare introduction signs and guidelines for participants. To prevent accidents such as dog bites, safety rules should be noticed in advance and animal experts such as animal trainers and vets need to be present.
+
+### **I.2.2 Main process**
+
+##### **I.2.2.1 Input metadata**
+
+Pet animals and their guardians who are participating in the database construction need to agree to the privacy policy. After the privacy policy is reviewed, the guardians input the metadata except for the biometrics of pet animals.
+
+##### **I.2.2.2 Prepare biometrics data acquisition**
+
+The cameras have to be placed at a distance of about 20 cm to 40 cm from a pet animal. Guardians hold up the face of their pet animals and help them remain calm. A part of the biometrics needs to be cleansed before the acquisition of the biometrics data.
+
+##### **I.2.2.3 Biometrics data acquisition**
+
+The biometrics should be acquired when the camera is well-focused on them. If there are many cameras, a capture timing must be aligned to the spot when more than two cameras are well-focused on the biometrics. The number of acquisitions is calculated based on the parameters of the type of place, illumination and camera angles. This process can be repeated until the biometrics have been collected in various conditions.
+
+**Table I.2 – Example of calculating the number of acquisition**
+
+| <b>The number of indoor illumination<br/>(A)</b> | <b>The number of outdoor illumination<br/>(B)</b> | <b>The number of pan parameters<br/>(C)</b> | <b>The number of tilt parameters<br/>(D)</b> | <b>The number of acquisition<br/>(E = (A + B)*C*D)</b> |
+|--------------------------------------------------|---------------------------------------------------|---------------------------------------------|----------------------------------------------|--------------------------------------------------------|
+| 3                                                | 1                                                 | 3                                           | 3                                            | 36                                                     |
+
+## **I.3 Metadata features**
+
+In this scenario, metadata features follow the features of clause 9.4.3.
+
+**Table I.3 – Common metadata of testing DB**
+
+| Class   | Features        | Type |
+|---------|-----------------|------|
+| DB_Info | Country         |      |
+|         | City            |      |
+|         | Supplier        |      |
+|         | RegisterDate    |      |
+|         | RevisionDate    |      |
+|         | RevisionHistory |      |
+|         | Version         |      |
+
+**Table I.4 – Environment and device metadata of testing DB**
+
+| Class            | Features            | Type |
+|------------------|---------------------|------|
+| Environment_Info | ExperimentCondition | Lux  |
+| Device_Info      | DeviceType          |      |
+|                  | MaxResolution       |      |
+
+**Table I.5 – Characteristic metadata of testing DB**
+
+| Class              | Features        | Type           |
+|--------------------|-----------------|----------------|
+| File_Info          | FileFormat      |                |
+|                    | FileName        |                |
+|                    | DirectoryPath   |                |
+|                    | FileSize        |                |
+| Biometrics_Info    | BiometricType   | Nose pattern   |
+|                    | RawData         | Image or video |
+|                    | ImageResolution |                |
+| Subject_Info       | BirthDate       |                |
+|                    | Gender          |                |
+|                    | Breed           |                |
+| Guardian_Info      | GuardianID      |                |
+| Miscellaneous_Info | OrderOfRepeat   |                |
+|                    | Comment         |                |
+
+## **I.4 Rescue service for lost pets based on pet entity authentication using telebiometrics**
+
+By executing performance tests, verified telebiometrics using the nose pattern of pet animals can be applied to rescue services for lost pets.
+
+# Appendix II
+
+## Use case for telebiometric entity authentication model for pet animals
+
+(This appendix does not form an integral part of this Recommendation.)
+
+## II.1 Requirements for an architecture of the pet entity authentication platform
+
+### II.1.1 Overview
+
+This scenario describes the use case and application of the pet entity authentication platform. This is a service that requires accurate identification of the pet animals, implements telebiometric features in its platform architecture and utilizes the unique ID of the pet animals with the unique ID of their guardians. One example of the pet entity authentication platform architecture is shown in Figure II.1.
+
+![Figure II.1 – The architecture of pet entity authentication platform](ab846b81e78dbc8da2a6f9511e2f248a_img.jpg)
+
+```
+graph LR; A[Launch platform  
+(WEB or APP)] --> B[Sign-up/in and  
+create an unique  
+ID of the guardian]; B --> C[Enrol their pet info  
+including biometrics]; C --> D[Store or match  
+guardian and  
+pet info]; D --> E((Enrolment or  
+authentication  
+complete)); B -- "Transfer metadata" --> F[(Guardian DB)]; C -- "Transfer metadata  
++  
+biometrics" --> G[(Pet DB including  
+biometrics)]; F -- "Transfer unique ID" --> G; G --> D;
+```
+
+X.1095(23)
+
+Figure II.1 – The architecture of pet entity authentication platform
+
+**Figure II.1 – The architecture of pet entity authentication platform**
+
+### II.1.2 Enrolment
+
+To use the specific features of the pet entity authentication platform such as pet adoption services and pet insurance, the guardians have to enrol their personal information and the information of their pet animals including biometrics (see Figure II.2). If there is duplicated information about the pet animal, the enrolment can be blocked to prevent an abusive event.
+
+![Figure II.2 – A flow chart of the sign-up and registration of the pet entity authentication platform](f0b7aaa539a2f77c98d53ed6c1c2366b_img.jpg)
+
+```
+graph LR; Start((Start)) --> A[Platform  
+sign-up]; A --> B[Input  
+guardian info]; B --> C[Input pet info  
+including  
+biometrics]; C --> D{Already  
+registered?}; D -- No --> E[Register pet info and  
+match with the unique  
+ID of their guardian info]; D -- Yes --> F{More pets?}; F -- Yes --> C; F -- No --> G((Finish)); E --> G;
+```
+
+X.1095(23)
+
+Figure II.2 – A flow chart of the sign-up and registration of the pet entity authentication platform
+
+**Figure II.2 – A flow chart of the sign-up and registration of the pet entity authentication platform**
+
+### II.1.3 Authentication
+
+The platform can set up the entity authentication process as a pre-requisite for providing the services such as delivering sensitive information about the pet animals and their guardians (see Figure II.3). When the guardians send a request to use a specific service, the platform retrieves the request to authenticate their pet animals. If the authentication results are output successfully, the guardians can use the service, but if the results fail to be output, the platform can refuse to provide the services to the guardians.
+
+![Flow chart of the sign-in and authentication of the pet entity authentication platform. The process starts with 'Start', followed by 'Platform sign-up with ID and password', 'Request services', and 'Receive the entity authentication request of the pet animal'. From here, it branches to 'Acquire biometrics of the pet animal'. This step connects to two databases: 'Pet DB including biometrics' (labeled 'Retrieved biometrics') and 'Guardian DB' (labeled 'Guardian ID'). Both lead to a decision 'Same pets?'. If 'Yes', it goes to 'Display pet info and provide the service' and then 'Finish'. If 'No', it goes directly to 'Finish'.](c5452f95f3b28f1bfe29e84fbc2e1267_img.jpg)
+
+```
+
+graph LR
+    Start([Start]) --> SignUp[Platform sign-up with ID and password]
+    SignUp --> Request[Request services]
+    Request --> Receive[Receive the entity authentication request of the pet animal]
+    Receive --> Acquire[Acquire biometrics of the pet animal]
+    Acquire -- Retrieved biometrics --> PetDB[(Pet DB including biometrics)]
+    Acquire -- Guardian ID --> GuardianDB[(Guardian DB)]
+    PetDB --> Same{Same pets?}
+    GuardianDB --> Same
+    Same -- Yes --> Display[Display pet info and provide the service]
+    Display --> Finish([Finish])
+    Same -- No --> Finish
+  
+```
+
+X.1095(23)
+
+Flow chart of the sign-in and authentication of the pet entity authentication platform. The process starts with 'Start', followed by 'Platform sign-up with ID and password', 'Request services', and 'Receive the entity authentication request of the pet animal'. From here, it branches to 'Acquire biometrics of the pet animal'. This step connects to two databases: 'Pet DB including biometrics' (labeled 'Retrieved biometrics') and 'Guardian DB' (labeled 'Guardian ID'). Both lead to a decision 'Same pets?'. If 'Yes', it goes to 'Display pet info and provide the service' and then 'Finish'. If 'No', it goes directly to 'Finish'.
+
+**Figure II.3 – A flow chart of the sign-in and authentication of the pet entity authentication platform**
+
+In the case of the guardian failing to authenticate their pet animal more than  $N$  times with the same biometrics, access to the platform can be blocked (see Figure II.4). To rearrange the pet animal to the platform after the block, the guardian should verify that the pet animal is the same as the previously registered one by submitting the other biometrics. A manager of the platform can determine whether the pet animal can be re-registered or not based on the submitted biometrics.
+
+![Flow chart of the failure case of the authentication. The process starts with 'Start', followed by 'Request services' and 'Authentication trial'. A decision 'Success?' follows. If 'Yes', it goes to 'Provide services'. If 'No', it goes to another decision 'More than N times?'. If 'Yes' to this second decision, it goes to 'Block services'. If 'No', it loops back to 'Authentication trial'.](ae53f90bb87d6d09e2d6b5278d7c338f_img.jpg)
+
+```
+
+graph LR
+    Start([Start]) --> Request[Request services]
+    Request --> Trial[Authentication trial]
+    Trial --> Success{Success?}
+    Success -- Yes --> Provide([Provide services])
+    Success -- No --> More{More than N times?}
+    More -- Yes --> Block([Block services])
+    More -- No --> Trial
+  
+```
+
+X.1095(23)
+
+Flow chart of the failure case of the authentication. The process starts with 'Start', followed by 'Request services' and 'Authentication trial'. A decision 'Success?' follows. If 'Yes', it goes to 'Provide services'. If 'No', it goes to another decision 'More than N times?'. If 'Yes' to this second decision, it goes to 'Block services'. If 'No', it loops back to 'Authentication trial'.
+
+**Figure II.4 – A flow chart of the failure case of the authentication**
+
+# Bibliography
+
+- [b-ISO 6196-7] ISO 6196-7:1992, *Micrographics – Vocabulary – Part 7: Computer micrographics*.  
+<<https://www.iso.org/obp/ui/en/#iso:std:iso:6196:-7:ed-1:v1:en>>
+- [b-ISO 20954-1] ISO 20954-1:2019, *Digital cameras – Measurement method for image stabilization performance – Part 1: Optical systems*.  
+<<https://www.iso.org/obp/ui/en/#iso:std:iso:20954:-1:ed-1:v1:en>>
+- [b-ISO 29301] ISO 29301:2017, *Microbeam analysis – Analytical electron microscopy – Methods for calibrating image magnification by using reference materials with periodic structures*.  
+<<https://www.iso.org/obp/ui/en/#iso:std:iso:29301:ed-2:v1:en>>
+- [b-ISO/IEC 19795-1] ISO/IEC 19795-1:2021, *Information technology – Biometric performance testing and reporting – Part 1: Principles and framework*.  
+<<https://www.iso.org/obp/ui/en/#iso:std:iso-iec:19795:-1:ed-2:v1:en>>
+- [b-ISO/IEC 2382-37] ISO/IEC 2382-37:2022, *Information technology – Vocabulary – Part 37: Biometrics*.  
+<<https://www.iso.org/obp/ui/en/#iso:std:iso-iec:2382:-37:ed-3:v1:en>>
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| Series F        | Non-telephone telecommunication services                                                                                                                  |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| <b>Series X</b> | <b>Data networks, open system communications and security</b>                                                                                             |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |