text stringlengths 17 3.36M | source stringlengths 3 333 | __index_level_0__ int64 0 518k |
|---|---|---|
In this dissertation, we present LaSCO, the Language for Security Constraints on Objects, a new approach to expressing security policies using policy graphs and present a method for enforcing policies so expressed. Other approaches for stating security policies fall short of what is desirable with respect to either policy clarity, executability, or the precision with which a policy may be expressed. However, LaSCO is designed to have those three desirable properties of a security policy language as well as: relevance for many different systems, statement of policies at an appropriate level of detail, user friendliness for both casual and expert users, and amenability to formal reasoning. In LaSCO, the constraints of a policy are stated as directed graphs annotated with expressions describing the situation under which the policy applies and what the requirement is. LaSCO may be used for such diverse applications as executing programs, file systems, operating systems, distributed systems, and networks. Formal operational semantics have been defined for LaSCO. An architecture for implementing LaSCO on any system, is presented along with an implementation of the system-independent portion in Perl. Using this, we have implemented LaSCO for Java programs, preventing Java programs from violating policy. A GUI to facilitate writing policies is provided. We have studied applying LaSCO to a network as viewed by GrIDS, a distributed intrusion detection system for large networks, and propose a design. We conclude that LaSCO has characteristics that enable its use on different types of systems throughout the process of precisely expressing a policy, understanding the implications of a policy, and implementing it on a system. | Specifying and Implementing Security Policies Using LaSCO, the Language
for Security Constraints on Objects | 7,800 |
We take a critical look at the relationship between the security of cryptographic schemes in the Random Oracle Model, and the security of the schemes that result from implementing the random oracle by so called "cryptographic hash functions". The main result of this paper is a negative one: There exist signature and encryption schemes that are secure in the Random Oracle Model, but for which any implementation of the random oracle results in insecure schemes. In the process of devising the above schemes, we consider possible definitions for the notion of a "good implementation" of a random oracle, pointing out limitations and challenges. | The Random Oracle Methodology, Revisited | 7,801 |
In this short note we want to introduce {\em anonymous oblivious transfer} a new cryptographic primitive which can be proven to be strictly more powerful than oblivious transfer. We show that all functions can be robustly realized by multi party protocols with {\em anonymous oblivious transfer}. No assumption about possible collusions of cheaters or disruptors have to be made. Furthermore we shortly discuss how to realize anonymous oblivious transfer with oblivious broadcast or by quantum cryptography. The protocol of anonymous oblivious transfer was inspired by a quantum protocol: the anonymous quantum channel. | Anonymous Oblivious Transfer | 7,802 |
With oblivious transfer multiparty protocols become possible even in the presence of a faulty majority. But all known protocols can be aborted by just one disruptor. This paper presents more robust solutions for multiparty protocols with oblivious transfer. This additional robustness against disruptors weakens the security of the protocol and the guarantee that the result is correct. We can observe a trade off between robustness against disruption and security and correctness. We give an application to quantum multiparty protocols. These allow the implementation of oblivious transfer and the protocols of this paper relative to temporary assumptions, i.e., the security increases after the termination of the protocol. | More Robust Multiparty Protocols with Oblivious Transfer | 7,803 |
This paper discusses mixing of chaotic systems as a dependable method for secure communication. Distribution of the entropy function for steady state as well as plaintext input sequences are analyzed. It is shown that the mixing of chaotic sequences results in a sequence that does not have any state dependence on the information encrypted by them. The generated output states of such a cipher approach the theoretical maximum for both complexity measures and cycle length. These features are then compared with some popular ciphers. | Chaos for Stream Cipher | 7,804 |
Suppose there is a group of N people some of whom possess a specific property. For example, their wealth is above or below a threshold, they voted for a particular candidate, they have a certain disease, etc. The group wants to find out how many of its members posses the property -- without revealing the identities. Unless of course it turns out that all members do or do not have the attribute of interest. However, in all other cases the counting algorithm should guarantee that nobody can find out if a particular individual possesses the property unless all the other N-1 members of the group collude. The present article describes a method to solve the confidential counting problem with only 3*N-2 pairwise communications, or 2*N broadcasts (the last N-1 pairwise communications are merely to announce the result). The counting algorithm does not require any trusted third parties. All communications between parties involved can be conducted in public without compromising the security of counting. | Secure Counting: counting members of a subset without revealing their
identities | 7,805 |
We consider zero knowledge interactive proofs in a richer, more realistic communication environment. In this setting, one may simultaneously engage in many interactive proofs, and these proofs may take place in an asynchronous fashion. It is known that zero-knowledge is not necessarily preserved in such an environment; we show that for a large class of protocols, it cannot be preserved. Any 4 round (computational) zero-knowledge interactive proof (or argument) for a non-trivial language L is not black-box simulatable in the asynchronous setting. | Lower Bounds for Zero-knowledge on the Internet | 7,806 |
A proof is concurrent zero-knowledge if it remains zero-knowledge when many copies of the proof are run in an asynchronous environment, such as the Internet. It is known that zero-knowledge is not necessarily preserved in such an environment. Designing concurrent zero-knowledge proofs is a fundamental issue in the study of zero-knowledge since known zero-knowledge protocols cannot be run in a realistic modern computing environment. In this paper we present a concurrent zero-knowledge proof systems for all languages in NP. Currently, the proof system we present is the only known proof system that retains the zero-knowledge property when copies of the proof are allowed to run in an asynchronous environment. Our proof system has $\tilde{O}(\log^2 k)$ rounds (for a security parameter $k$), which is almost optimal, as it is shown by Canetti Kilian Petrank and Rosen that black-box concurrent zero-knowledge requires $\tilde{\Omega}(\log k)$ rounds. Canetti, Goldreich, Goldwasser and Micali introduced the notion of {\em resettable} zero-knowledge, and modified an earlier version of our proof system to obtain the first resettable zero-knowledge proof system. This protocol requires $k^{\theta(1)}$ rounds. We note that their technique also applies to our current proof system, yielding a resettable zero-knowledge proof for NP with $\tilde{O}(\log^2 k)$ rounds. | On Concurrent and Resettable Zero-Knowledge Proofs for NP | 7,807 |
This paper discusses the security considerations for remote electronic voting in public elections. In particular, we examine the feasibility of running national federal elections over the Internet. The focus of this paper is on the limitations of the current deployed infrastructure in terms of the security of the hosts and the Internet itself. We conclude that at present, our infrastructure is inadequate for remote Internet voting. | Security Considerations for Remote Electronic Voting over the Internet | 7,808 |
The early promises of DNA computing to deliver a massively parallel architecture well-suited to computationally hard problems have so far been largely unkept. Indeed, it is probably fair to say that only toy problems have been addressed experimentally. Recent experimental development on algorithmic self-assembly using DNA tiles seem to offer the most promising path toward a potentially useful application of the DNA computing concept. In this paper, we explore new geometries for algorithmic self-assembly, departing from those previously described in the literature. This enables us to carry out mathematical operations like binary multiplication or cyclic convolution product. We then show how to use the latter operation to implement an attack against the well-known public-key crypto system NTRU. | Algorithmic Self-Assembly of DNA Tiles and its Application to
Cryptanalysis | 7,809 |
The approach for a network behavior description in terms of numerical time-dependant functions of the protocol parameters is suggested. This provides a basis for application of methods of mathematical and theoretical physics for information flow analysis on network and for extraction of patterns of typical network behavior. The information traffic can be described as a trajectory in multi-dimensional parameter-time space with dimension about 10-12. Based on this study some algorithms for the proposed intrusion detection system are discussed. | New approach for network monitoring and intrusion detection | 7,810 |
We propose pretty simple password-authenticated key-exchange protocol which is based on the difficulty of solving DDH problem. It has the following advantages: (1) Both $y_1$ and $y_2$ in our protocol are independent and thus they can be pre-computed and can be sent independently. This speeds up the protocol. (2) Clients and servers can use almost the same algorithm. This reduces the implementation costs without accepting replay attacks and abuse of entities as oracles. | Pretty-Simple Password-Authenticated Key-Exchange Protocol | 7,811 |
Random beacons-information sources that broadcast a stream of random digits unknown by anyone beforehand-are useful for various cryptographic purposes. But such beacons can be easily and undetectably sabotaged, so that their output is known beforehand by a dishonest party, who can use this information to defeat the cryptographic protocols supposedly protected by the beacon. We explore a strategy to reduce this hazard by combining the outputs from several noninteracting (eg spacelike-separated) beacons by XORing them together to produce a single digit stream which is more trustworthy than any individual beacon, being random and unpredictable if at least one of the contributing beacons is honest. If the contributing beacons are not spacelike separated, so that a dishonest beacon can overhear and adapt to earlier outputs of other beacons, the beacons' trustworthiness can still be enhanced to a lesser extent by a time sharing strategy. We point out some disadvantages of alternative trust amplification methods based on one-way hash functions. | Trust enhancement by multiple random beacons | 7,812 |
An approach for real-time network monitoring in terms of numerical time-dependant functions of protocol parameters is suggested. Applying complex systems theory for information f{l}ow analysis of networks, the information traffic is described as a trajectory in multi-dimensional parameter-time space with about 10-12 dimensions. The network traffic description is synthesized by applying methods of theoretical physics and complex systems theory, to provide a robust approach for network monitoring that detects known intrusions, and supports developing real systems for detection of unknown intrusions. The methods of data analysis and pattern recognition presented are the basis of a technology study for an automatic intrusion detection system that detects the attack in the reconnaissance stage. | Multidimensional Network Monitoring for Intrusion Detection | 7,813 |
An important problem of modern cryptography concerns secret public-key computations in algebraic structures. We construct homomorphic cryptosystems being (secret) epimorphisms f:G --> H, where G, H are (publically known) groups and H is finite. A letter of a message to be encrypted is an element h element of H, while its encryption g element of G is such that f(g)=h. A homomorphic cryptosystem allows one to perform computations (operating in a group G) with encrypted information (without knowing the original message over H). In this paper certain homomorphic cryptosystems are constructed for the first time for non-abelian groups H (earlier, homomorphic cryptosystems were known only in the Abelian case). In fact, we present such a system for any solvable (fixed) group H. | On non-abelian homomorphic public-key cryptosystems | 7,814 |
In this paper homomorphic cryptosystems are designed for the first time over any finite group. Applying Barrington's construction we produce for any boolean circuit of the logarithmic depth its encrypted simulation of a polynomial size over an appropriate finitely generated group. | Homomorphic public-key cryptosystems and encrypting boolean circuits | 7,815 |
In this note, we describe a probabilistic attack on public key cryptosystems based on the word/conjugacy problems for finitely presented groups of the type proposed recently by Anshel, Anshel and Goldfeld. In such a scheme, one makes use of the property that in the given group the word problem has a polynomial time solution, while the conjugacy problem has no known polynomial solution. An example is the braid group from topology in which the word problem is solvable in polynomial time while the only known solutions to the conjugacy problem are exponential. The attack in this paper is based on having a canonical representative of each string relative to which a length function may be computed. Hence the term length attack. Such canonical representatives are known to exist for the braid group. | Length-Based Attacks for Certain Group Based Encryption Rewriting
Systems | 7,816 |
Strand spaces are a popular framework for the analysis of security protocols. Strand spaces have some similarities to a formalism used successfully to model protocols for distributed systems, namely multi-agent systems. We explore the exact relationship between these two frameworks here. It turns out that a key difference is the handling of agents, which are unspecified in strand spaces and explicit in multi-agent systems. We provide a family of translations from strand spaces to multi-agent systems parameterized by the choice of agents in the strand space. We also show that not every multi-agent system of interest can be expressed as a strand space. This reveals a lack of expressiveness in the strand-space framework that can be characterized by our translation. To highlight this lack of expressiveness, we show one simple way in which strand spaces can be extended to model more systems. | On the Relationship between Strand Spaces and Multi-Agent Systems | 7,817 |
The basic properties of RSA cryptosystems and some classical attacks on them are described. Derived from geometric properties of the Euler functions, the Euler function rays, a new ansatz to attack RSA cryptosystems is presented. A resulting, albeit inefficient, algorithm is given. It essentially consists of a loop with starting value determined by the Euler function ray and with step width given by a function $\omega_e(n)$ being a multiple of the order $\mathrm{ord}_n(e)$, where $e$ denotes the public key exponent and $n$ the RSA modulus. For $n=pq$ and an estimate $r<\sqrt{pq}$ for the smaller prime factor $p$, the running time is given by $T(e,n,r) = O((r-p)\ln e \ln n \ln r).$ | The ray attack, an inefficient trial to break RSA cryptosystems | 7,818 |
A group authentication protocol authenticates pre-defined groups of individuals such that: - No individual is identified - No knowledge of which groups can be successfully authenticated is known to the verifier - No sensitive data is exposed The paper presents a group authentication protocol based on splitting the private keys of the Naccache-Stern public-key cryptosystem in such a way that the Boolean expression defining the authenticable groups is implicit in the split. | Group Authentication Using The Naccache-Stern Public-Key Cryptosystem | 7,819 |
We propose a new homomorphic public-key cryptosystem over arbitrary nonidentity finite group based on the difficulty of the membership problem for groups of integer matrices. Besides, a homomorphic cryptosystem is designed for the first time over finite commutative rings. | Homomorphic public-key cryptosystems over groups and rings | 7,820 |
We introduce the use of Fourier analysis on lattices as an integral part of a lattice based construction. The tools we develop provide an elegant description of certain Gaussian distributions around lattice points. Our results include two cryptographic constructions which are based on the worst-case hardness of the unique shortest vector problem. The main result is a new public key cryptosystem whose security guarantee is considerably stronger than previous results ($O(n^{1.5})$ instead of $O(n^7)$). This provides the first alternative to Ajtai and Dwork's original 1996 cryptosystem. Our second result is a family of collision resistant hash functions which, apart from improving the security in terms of the unique shortest vector problem, is also the first example of an analysis which is not based on Ajtai's iterative step. Surprisingly, both results are derived from one theorem which presents two indistinguishable distributions on the segment $[0,1)$. It seems that this theorem can have further applications and as an example we mention how it can be used to solve an open problem related to quantum computation. | New Lattice Based Cryptographic Constructions | 7,821 |
In the paper we discuss how to share the secrets, that are graphs. So, far secret sharing schemes were designed to work with numbers. As the first step, we propose conditions for "graph to number" conversion methods. Hence, the existing schemes can be used, without weakening their properties. Next, we show how graph properties can be used to extend capabilities of secret sharing schemes. This leads to proposal of using such properties for number based secret sharing. | On secret sharing for graphs | 7,822 |
At the beginning some results from the field of graph theory are presented. Next we show how to share a secret that is proper n-coloring of the graph, with the known structure. The graph is described and converted to the form, where colors assigned to vertices form the number with entries from Zn. A secret sharing scheme (SSS) for the graph coloring is proposed. The proposed method is applied to the public-key cryptosystem called "Polly Cracker". In this case the graph structure is a public key, while proper 3-colouring of the graph is a private key. We show how to share the private key. Sharing particular n-coloring (color-to-vertex assignment) for the known-structure graph is presented next. | Secret Sharing for n-Colorable Graphs with Application to Public Key
Cryptography | 7,823 |
A {k,n}-threshold scheme based on two-dimensional memory cellular automata is proposed to share images in a secret way. This method allows to encode an image into n shared images so that only qualified subsets of k or more shares can recover the secret image, but any k-1 or fewer of them gain no information about the original image. The main characteristics of this new scheme are: each shared image has the same size that the original one, and the recovered image is exactly the same than the secret image; i.e., there is no loss of resolution. | Sharing secret color images using cellular automata with memory | 7,824 |
The paper study counter-dependent pseudorandom generators; the latter are generators such that their state transition function (and output function) is being modified dynamically while working: For such a generator the recurrence sequence of states satisfies a congruence $x_{i+1}\equiv f_i(x_i)\pmod{2^n}$, while its output sequence is of the form $z_{i}=F_i(u_i)$. The paper introduces techniques and constructions that enable one to compose generators that output uniformly distributed sequences of a maximum period length and with high linear and 2-adic spans. The corresponding stream chipher is provably strong against a known plaintext attack (up to a plausible conjecture). Both state transition function and output function could be key-dependent, so the only information available to a cryptanalyst is that these functions belong to some (exponentially large) class. These functions are compositions of standard machine instructions (such as addition, multiplication, bitwise logical operations, etc.) The compositions should satisfy rather loose conditions; so the corresponding generators are flexible enough and could be easily implemented as computer programs. | Pseudorandom number generation by $p$-adic ergodic transformations | 7,825 |
Unsolicited bulk email (aka. spam) is a major problem on the Internet. To counter spam, several techniques, ranging from spam filters to mail protocol extensions like hashcash, have been proposed. In this paper we investigate the effectiveness of several spam filtering techniques and technologies. Our analysis was performed by simulating email traffic under different conditions. We show that genetic algorithm based spam filters perform best at server level and naive Bayesian filters are the most appropriate for filtering at user level. | Spam filter analysis | 7,826 |
A discrete-time discrete-value pseudo-chaotic encoder/decoder system is presented. The pseudo-chaotic module is a 3D discrete version of the well-known Lorenz dynamical system. Scaling and biasing transformations as well as natural number arithmetics are employed in order to simplify realizations on a small size Field Programmable Gate Array (FPGA. The encryption ability is improved by using only the least significant byte of one of the pseudo chaotic state variables as the key to encrypt the plain text. The key is periodically perturbed by another chaotic state variable. The statistical properties of the pseudo chaotic cipher are compared with those of other pseudo-random generators available in the literature. As an example of applicability of the technique, a full duplex communication system is designed and constructed using FPGA's as technological framework. | Digital Signal Transmission with Chaotic Encryption: Design and
Evaluation of a FPGA Realization | 7,827 |
The paper study counter-dependent pseudorandom number generators based on $m$-variate ($m>1$) ergodic mappings of the space of 2-adic integers $\Z_2$. The sequence of internal states of these generators is defined by the recurrence law $\mathbf x_{i+1}= H^B_i(\mathbf x_i)\bmod{2^n}$, whereas their output sequence is %while its output sequence is of the $\mathbf z_{i}=F^B_i(\mathbf x_i)\mod 2^n$; here $\mathbf x_j, \mathbf z_j$ are $m$-dimensional vectors over $\Z_2$. It is shown how the results obtained for a univariate case could be extended to a multivariate case. | Pseudorandom number generation by p-adic ergodic transformations: an
addendum | 7,828 |
A new scheme for transmitting sensitive data is proposed, the proposed scheme depends on partitioning the output of a block encryption module using the Chinese Remainder Theorem among a set of channels. The purpose of using the Chinese Remainder Theorem is to hide the cipher text in order to increase the difficulty of attacking the cipher. The theory, implementation and the security of this scheme are described in this paper. | Secure Transmission of Sensitive data using multiple channels | 7,829 |
In this paper we design a stream cipher that uses the algebraic structure of the multiplicative group $\bbbz_p^*$ (where p is a big prime number used in ElGamal algorithm), by defining a quasigroup of order $p-1$ and by doing quasigroup string transformations. The cryptographical strength of the proposed stream cipher is based on the fact that breaking it would be at least as hard as solving systems of multivariate polynomial equations modulo big prime number $p$ which is NP-hard problem and there are no known fast randomized or deterministic algorithms for solving it. Unlikely the speed of known ciphers that work in $\bbbz_p^*$ for big prime numbers $p$, the speed of this stream cipher both in encryption and decryption phase is comparable with the fastest symmetric-key stream ciphers. | Stream cipher based on quasigroup string transformations in $Z_p^*$ | 7,830 |
We propose a cipher similar to the One Time Pad and McEliece cipher based on a subband coding scheme. The encoding process is an approximation to the One Time Pad encryption scheme. We present results of numerical experiments which suggest that a brute force attack to the proposed scheme does not result in all possible plaintexts, as the One Time Pad does, but still the brute force attack does not compromise the system. However, we demonstrate that the cipher is vulnerable to a chosen-plaintext attack. | Encryption Schemes using Finite Frames and Hadamard Arrays | 7,831 |
Security of computers and the networks that connect them is increasingly becoming of great significance. Computer security is defined as the protection of computing systems against threats to confidentiality, integrity, and availability. There are two types of intruders: external intruders, who are unauthorized users of the machines they attack, and internal intruders, who have permission to access the system with some restrictions. This chapter presents a soft computing approach to detect intrusions in a network. Among the several soft computing paradigms, we investigated fuzzy rule-based classifiers, decision trees, support vector machines, linear genetic programming and an ensemble method to model fast and efficient intrusion detection systems. Empirical results clearly show that soft computing approach could play a major role for intrusion detection. | Soft Computing Models for Network Intrusion Detection Systems | 7,832 |
In this paper, we present a novel encryption-less algorithm to enhance security in transmission of data in networks. The algorithm uses an intuitively simple idea of a 'jigsaw puzzle' to break the transformed data into multiple parts where these parts form the pieces of the puzzle. Then these parts are packaged into packets and sent to the receiver. A secure and efficient mechanism is provided to convey the information that is necessary for obtaining the original data at the receiver-end from its parts in the packets, that is, for solving the 'jigsaw puzzle'. The algorithm is designed to provide information-theoretic (that is, unconditional) security by the use of a one-time pad like scheme so that no intermediate or unintended node can obtain the entire data. An authentication code is also used to ensure authenticity of every packet. | Jigsaw-based Security in Data Transfer in Computer Networks | 7,833 |
In peer-to-peer systems, attrition attacks include both traditional, network-level denial of service attacks as well as application-level attacks in which malign peers conspire to waste loyal peers' resources. We describe several defenses for LOCKSS, a peer-to-peer digital preservation system, that help ensure that application-level attacks even from powerful adversaries are less effective than simple network-level attacks, and that network-level attacks must be intense, wide-spread, and prolonged to impair the system. | Attrition Defenses for a Peer-to-Peer Digital Preservation System | 7,834 |
Electronic bait (honeypots) are network resources whose value consists of being attacked and compromised. These are often computers which do not have a task in the network, but are otherwise indestinguishable from regular computers. Such bait systems could be interconnected (honeynets). These honeynets are equipped with special software, facilitating forensic anylisis of incidents. Taking average of the wide variety of recorded data it is possible to learn considerable more about the behaviour of attackers in networks than with traditional methods. This article is an introduction into electronic bait and a description of the setup and first experiences of such a network deployed at RWTH Aachen University. ----- Als elektronische Koeder (honeypots) bezeichnet man Netzwerkressourcen, deren Wert darin besteht, angegriffen und kompromittiert zu werden. Oft sind dies Computer, die keine spezielle Aufgabe im Netzwerk haben, aber ansonsten nicht von regulaeren Rechnern zu unterscheiden sind. Koeder koennen zu Koeder-Netzwerken (honeynets) zusammengeschlossen werden. Sie sind mit spezieller Software ausgestattet, die die Forensik einer eingetretenen Schutzzielverletzung erleichtert. Durch die Vielfalt an mitgeschnittenen Daten kann man deutlich mehr ueber das Verhalten von Angreifern in Netzwerken lernen als mit herkoemmlichen forensischen Methoden. Dieser Beitrag stellt die Philosophie der Koeder-Netzwerke vor und beschreibt die ersten Erfahrungen, die mit einem solchen Netzwerk an der RWTH Aachen gemacht wurden. | Ermittlung von Verwundbarkeiten mit elektronischen Koedern | 7,835 |
In 2004, W. C. Ku and S. M. Chen proposed an efficient remote user authentication scheme using smart cards to solve the security problems of Chien et al.'s scheme. Recently, Hsu and Yoon et al. pointed out the security weaknesses of the Ku and Chen's scheme Furthermore, Yoon et al. also proposed a new efficient remote user authentication scheme using smart cards. Yoon et al. also modified the password change phase of Ku and Chen's scheme. This paper analyzes that password change phase of Yoon et al's modified scheme is still insecure. | The Password Change Phase is Still Insecure | 7,836 |
Logs are one of the most fundamental resources to any security professional. It is widely recognized by the government and industry that it is both beneficial and desirable to share logs for the purpose of security research. However, the sharing is not happening or not to the degree or magnitude that is desired. Organizations are reluctant to share logs because of the risk of exposing sensitive information to potential attackers. We believe this reluctance remains high because current anonymization techniques are weak and one-size-fits-all--or better put, one size tries to fit all. We must develop standards and make anonymization available at varying levels, striking a balance between privacy and utility. Organizations have different needs and trust other organizations to different degrees. They must be able to map multiple anonymization levels with defined risks to the trust levels they share with (would-be) receivers. It is not until there are industry standards for multiple levels of anonymization that we will be able to move forward and achieve the goal of widespread sharing of logs for security researchers. | Sharing Computer Network Logs for Security and Privacy: A Motivation for
New Methodologies of Anonymization | 7,837 |
This paper proposes a signature scheme where the signatures are generated by the cooperation of a number of people from a given group of senders and the signatures are verified by a certain number of people from the group of recipients. Shamir's threshold scheme and Schnorr's signature scheme are used to realize the proposed scheme. | A Digital Signature with Threshold Generation and Verification | 7,838 |
This report surveys different PKI technologies such as PKIX and SPKI and the issues of PKI that affect scalability. Much focus is spent on certificate revocation methodologies and status verification systems such as CRLs, Delta-CRLs, CRS, Certificate Revocation Trees, Windowed Certificate Revocation, OCSP, SCVP and DVCS. | PKI Scalability Issues | 7,839 |
This paper presents a directed signature scheme with the property that the signature can be verified only with the help of signer or signature receiver. We also propose its applications to share verification of signatures and to threshold cryptosystems. | A Directed Signature Scheme and its Applications | 7,840 |
In this paper, we propose a Directed Threshold Multi-Signature Scheme. In this threshold signature scheme, any malicious set of signers cannot impersonate any other set of signers to forge the signatures. In case of forgery, it is possible to trace the signing set. This threshold signature scheme is applicable when the message is sensitive to the signature receiver; and the signatures are generated by the cooperation of a number of people from a given group of senders. | A Directed -Threshold Multi-Signature Scheme | 7,841 |
Directed signature scheme is applicable when the signed message contains information sensitive to the receiver, because only receiver can directly verify the signature and that he/she can prove its validity to any third party, whenever necessary. This paper presents two applications of directed signature scheme. (i) Directed –Delegated Signature Scheme. This scheme combines the idea of proxy signatures with directed signature scheme. (ii) Allocation of registration number. This scheme proposes a registration scheme in which the registration number cannot be forged and misused. | Some Applications of Directed Signature Scheme | 7,842 |
Since 1981, when Lamport introduced the remote user authentication scheme using table, a plenty of schemes had been proposed with tables or without table using. Recently Das et al. proposed a dynamic id-based remote user authentication scheme. They claimed that their scheme is secure against ID-theft, and can resist the reply attacks, forgery attacks, insider attacks an so on. In this paper we show that Das et al's scheme is completly insecure and using of this scheme is like an open server access without password. | Comment on A dynamic ID-based Remote User Authentication Scheme | 7,843 |
We model a private key`s life cycle as a finite state machine. The states are the key`s phases of life and the transition functions describe tasks to be done with the key. Based on this we define and describe the key authority, a trust center module, which potentiates the easy enforcement of secure management of private keys in hierarchical public key infrastructures. This is done by assembling all trust center tasks concerning the crucial handling of private keys within one centralized module. As this module resides under full control of the trust center`s carrier it can easily be protected by well-known organizational and technical measures. | The Key Authority - Secure Key Management in Hierarchical Public Key
Infrastructures | 7,844 |
The PIN/TAN-system is an authentication and authorization scheme used in e-business. Like other similar schemes it is successfully attacked by criminals. After shortly classifying the various kinds of attacks we accomplish malicious code attacks on real World Wide Web transaction systems. In doing so we find that it is really easy to outflank these systems. This is even supported by the users' behavior. We give a few simple behavior rules to improve this situation. But their impact is limited. Also the providers support the attacks by having implementation flaws in their installations. Finally we show that the PIN/TAN-system is not suitable for usage in highly secure applications. | Outflanking and securely using the PIN/TAN-System | 7,845 |
Directed signature is the solution of such problems when the signed message contains information sensitive to the signature receiver. Generally, in many application of directed signature, the signer is generally a single person. But when the message is on behalf of an organization, a valid sensitive message may require the approval of several people. Threshold signature schemes are used to solve these problems. This paper presents a threshold directed signature scheme. | A Directed Threshold - Signature Scheme | 7,846 |
We propose a new simple \emph{trace} logic that can be used to specify \emph{local security properties}, i.e. security properties that refer to a single participant of the protocol specification. Our technique allows a protocol designer to provide a formal specification of the desired security properties, and integrate it naturally into the design process of cryptographic protocols. Furthermore, the logic can be used for formal verification. We illustrate the utility of our technique by exposing new attacks on the well studied protocol TMN. | A Trace Logic for Local Security Properties | 7,847 |
Chebyshev polynomials have been recently proposed for designing public-key systems. Indeed, they enjoy some nice chaotic properties, which seem to be suitable for use in Cryptography. Moreover, they satisfy a semi-group property, which makes possible implementing a trapdoor mechanism. In this paper we study a public key cryptosystem based on such polynomials, which provides both encryption and digital signature. The cryptosystem works on real numbers and is quite efficient. Unfortunately, from our analysis it comes up that it is not secure. We describe an attack which permits to recover the corresponding plaintext from a given ciphertext. The same attack can be applied to produce forgeries if the cryptosystem is used for signing messages. Then, we point out that also other primitives, a Diffie-Hellman like key agreement scheme and an authentication scheme, designed along the same lines of the cryptosystem, are not secure due to the aforementioned attack. We close the paper by discussing the issues and the possibilities of constructing public key cryptosystems on real numbers. | Security of public key cryptosystems based on Chebyshev Polynomials | 7,848 |
In this paper we present an image retrieval system based on Gabor texture features, steganography, and mobile agents.. By employing the information hiding technique, the image attributes can be hidden in an image without degrading the image quality. Thus the image retrieval process becomes simple. Java based mobile agents manage the query phase of the system. Based on the simulation results, the proposed system not only shows the efficiency in hiding the attributes but also provides other advantages such as: (1) fast transmission of the retrieval image to the receiver, (2) searching made easy. | Content Based Image Retrieval with Mobile Agents and Steganography | 7,849 |
National Root CAs enable legally binding E-Business and E-Government transactions. This is a report about the development, the evaluation and the certification of the new certification services system for the German National Root CA. We illustrate why a new certification services system was necessary, and which requirements to the new system existed. Then we derive the tasks to be done from the mentioned requirements. After that we introduce the initial situation at the beginning of the project. We report about the very process and talk about some unfamiliar situations, special approaches and remarkable experiences. Finally we present the ready IT system and its impact to E-Business and E-Government. | An Evaluated Certification Services System for the German National Root
CA - Legally Binding and Trustworthy Transactions in E-Business and
E-Government | 7,850 |
We present a framework for extending the functionality of LDAP servers from their typical use as a public directory in public key infrastructures. In this framework the LDAP servers are used for administrating infrastructure processes. One application of this framework is a method for providing proof-of-possession, especially in the case of encryption keys. Another one is the secure delivery of software personal security environments. | Using LDAP Directories for Management of PKI Processes | 7,851 |
This paper proposes the Intra Trustcenter Protocol (ITP), a flexible and secure management protocol for communication between arbitrary trustcenter components. Unlike other existing protocols (like PKCS#7, CMP or XKMS) ITP focuses on the communication within a trustcenter. It is powerful enough for transferring complex messages which are machine and human readable and easy to understand. In addition it includes an extension mechanism to be prepared for future developments. | Towards a Flexible Intra-Trustcenter Management Protocol | 7,852 |
In this paper we provide a guide for public key infrastructure designers and administrators when planning for directory services. We concentrate on the LDAP directories and how they can be used to successfully publish PKI information. We analyse their available mechanisms and propose a best practice guide for use in PKI. We then take a look into the German Signature Act and Ordinance and discuss their part as far as directories concerning. Finally, we translate those to the LDAP directories practices. | Planning for Directory Services in Public Key Infrastructures | 7,853 |
Web services security specifications are typically expressed as a mixture of XML schemas, example messages, and narrative explanations. We propose a new specification language for writing complementary machine-checkable descriptions of SOAP-based security protocols and their properties. Our TulaFale language is based on the pi calculus (for writing collections of SOAP processors running in parallel), plus XML syntax (to express SOAP messaging), logical predicates (to construct and filter SOAP messages), and correspondence assertions (to specify authentication goals of protocols). Our implementation compiles TulaFale into the applied pi calculus, and then runs Blanchet's resolution-based protocol verifier. Hence, we can automatically verify authentication properties of SOAP protocols. | TulaFale: A Security Tool for Web Services | 7,854 |
An XML web service is, to a first approximation, an RPC service in which requests and responses are encoded in XML as SOAP envelopes, and transported over HTTP. We consider the problem of authenticating requests and responses at the SOAP-level, rather than relying on transport-level security. We propose a security abstraction, inspired by earlier work on secure RPC, in which the methods exported by a web service are annotated with one of three security levels: none, authenticated, or both authenticated and encrypted. We model our abstraction as an object calculus with primitives for defining and calling web services. We describe the semantics of our object calculus by translating to a lower-level language with primitives for message passing and cryptography. To validate our semantics, we embed correspondence assertions that specify the correct authentication of requests and responses. By appeal to the type theory for cryptographic protocols of Gordon and Jeffrey's Cryptyc, we verify the correspondence assertions simply by typing. Finally, we describe an implementation of our semantics via custom SOAP headers. | Validating a Web Service Security Abstraction by Typing | 7,855 |
The remarkably long-standing problem of cryptography is to generate completely secure key. It is widely believed that the task cannot be achieved within classical cryptography. However, there is no proof in support of this belief. We present an incredibly simple classical cryptosystem which can generate completely secure key. | An unbreakable cryptosystem | 7,856 |
Distributed intrustion detection systems detect attacks on computer systems by analyzing data aggregated from distributed sources. The distributed nature of the data sources allows patterns in the data to be seen that might not be detectable if each of the sources were examined individually. This paper describes the various approaches that have been developed to share and analyze data in such systems, and discusses some issues that must be addressed before fully decentralized distributed intrusion detection systems can be made viable. | A Survey of Distributed Intrusion Detection Approaches | 7,857 |
In this thesis, we propose some directed signature schemes. In addition, we have discussed their applications in different situations. In this thesis, we would like to discuss the security aspects during the design process of the proposed directed digital signature schemes. The security of the most digital signature schemes widely use in practice is based on the two difficult problems, viz; the problem of factoring integers (The RSA scheme) and the problem of finding discrete logarithms over finite fields (The ElGamal scheme). The proposed works in this thesis is divided into seven chapters. | A Cryptographic Study of Some Digital Signature Schemes | 7,858 |
Over the recent months it has become clear that the current generation of cryptographic hashing algorithms are insufficient to meet future needs. The ASH family of algorithms provides modifications to the existing SHA-2 family. These modifications are designed with two main goals: 1) Providing increased collision resistance. 2) Increasing mitigation of security risks post-collision. The unique public/private sections and salt/pepper design elements provide increased flexibility for a broad range of applications. The ASH family is a new generation of cryptographic hashing algorithms. | Data Tastes Better Seasoned: Introducing the ASH Family of Hashing
Algorithms | 7,859 |
In 2000, Hwang and Li proposed a remote user authentication scheme using smart cards to solve the problems of Lamport scheme. Later, Chan- Chang, Shen- Lin- Hwang and then Chang-Hwang pointed out some attacks on Hwang – Li’s scheme. In 2003, Shen, Lin and Hwang also proposed a modified scheme to remove these attacks. In the same year, Leung-Cheng-Fong-Chan showed that modified scheme proposed by Shen-Lin-Hwang is still insecure. In 2004, Awasthi and Lal enhanced Shen-Lin-Hwang’s scheme to overcome its security pitfalls. This paper analyses that the user U/smart card does not provide complete information for the execution and proper running of the login phase of the Awasthi- Lal’s scheme. Furthermore, this paper also modifies the Awasthi- Lal’s scheme for the proper functioning. | Faults and Improvements of an Enhanced Remote User Authentication Scheme
Using Smart Cards | 7,860 |
In this paper, we propose a Directed threshold multisignature scheme without SDC. This signature scheme is applicable when the message is sensitive to the signature receiver; and the signatures are generated by the cooperation of a number of people from a given group of senders. In this scheme, any malicious set of signers cannot impersonate any other set of signers to forge the signatures. In case of forgery, it is possible to trace the signing set. | Directed Threshold Multi – Signature Scheme without SDC | 7,861 |
We propose a method for engineering security protocols that are aware of timing aspects. We study a simplified version of the well-known Needham Schroeder protocol and the complete Yahalom protocol, where timing information allows the study of different attack scenarios. We model check the protocols using UPPAAL. Further, a taxonomy is obtained by studying and categorising protocols from the well known Clark Jacob library and the Security Protocol Open Repository (SPORE) library. Finally, we present some new challenges and threats that arise when considering time in the analysis, by providing a novel protocol that uses time challenges and exposing a timing attack over an implementation of an existing security protocol. | Timed Analysis of Security Protocols | 7,862 |
One-way hash chains have been used in many micropayment schemes due to their simplicity and efficiency. In this paper we introduce the notion of multi-dimensional hash chains, which is a new generalization of traditional one-way hash chains. We show that this construction has storage-computational complexity of O(logN) per chain element, which is comparable with the best result reported in recent literature. Based on multi-dimensional hash chains, we then propose two cash-like micropayment schemes, which have a number of advantages in terms of efficiency and security. We also point out some possible improvements to PayWord and similar schemes by using multi-dimensional hash chains | Multi-Dimensional Hash Chains and Application to Micropayment Schemes | 7,863 |
During the last years, large-scale simulations of realistic physical environments which support the interaction of multiple participants over the Internet have become increasingly available and economically significant, most notably in the computer gaming industry. Such systems, commonly called networked virtual environments (NVEs), are usually based on a client-server architecture where for performance reasons and bandwidth restrictions, the simulation is partially deferred to the clients. This inevitable architectural choice renders the simulation vulnerable to attacks against the semantic integrity of the simulation: malicious clients may attempt to compromise the physical and logical laws governing the simulation, or to alter the causality of events a posteriori. In this paper, we initiate the systematic study of semantic integrity in NVEs from a security point of view. We argue that naive policies to enforce semantic integrity involve intolerable network load, and are therefore not practically feasible. We present a new semantic integrity protocol based on cryptographic primitives which enables the server system to audit the local computations of the clients on demand. Our approach facilitates low network and CPU load, incurs reasonable engineering overhead, and maximally decouples the auditing process from the soft real time constraints of the simulation. | Enforcing Semantic Integrity on Untrusted Clients in Networked Virtual
Environments | 7,864 |
We propose a new detection algorithm that uses structural relationships between senders and recipients of email as the basis for the identification of spam messages. Users and receivers are represented as vectors in their reciprocal spaces. A measure of similarity between vectors is constructed and used to group users into clusters. Knowledge of their classification as past senders/receivers of spam or legitimate mail, comming from an auxiliary detection algorithm, is then used to label these clusters probabilistically. This knowledge comes from an auxiliary algorithm. The measure of similarity between the sender and receiver sets of a new message to the center vector of clusters is then used to asses the possibility of that message being legitimate or spam. We show that the proposed algorithm is able to correct part of the false positives (legitimate messages classified as spam) using a testbed of one week smtp log. | Improving Spam Detection Based on Structural Similarity | 7,865 |
An authenticated encryption scheme allows messages to be encrypted and authenticated simultaneously. In 2003, Ma and Chen proposed such a scheme with public verifiability. That is, in their scheme the receiver can efficiently prove to a third party that a message is indeed originated from a specific sender. In this paper, we first identify two security weaknesses in the Ma-Chen authenticated encryption scheme. Then, based on the Schnorr signature, we proposed an efficient and secure improved scheme such that all the desired security requirements are satisfied. | Efficient Authenticated Encryption Schemes with Public Verifiability | 7,866 |
Internet worms have become a widespread threat to system and network operations. In order to fight them more efficiently, it is necessary to analyze newly discovered worms and attack patterns. This paper shows how techniques based on Kolmogorov Complexity can help in the analysis of internet worms and network traffic. Using compression, different species of worms can be clustered by type. This allows us to determine whether an unknown worm binary could in fact be a later version of an existing worm in an extremely simple, automated, manner. This may become a useful tool in the initial analysis of malicious binaries. Furthermore, compression can also be useful to distinguish different types of network traffic and can thus help to detect traffic anomalies: Certain anomalies may be detected by looking at the compressibility of a network session alone. We furthermore show how to use compression to detect malicious network sessions that are very similar to known intrusion attempts. This technique could become a useful tool to detect new variations of an attack and thus help to prevent IDS evasion. We provide two new plugins for Snort which demonstrate both approaches. | Analyzing Worms and Network Traffic using Compression | 7,867 |
In 2000, Hwang and Li proposed a new remote user authentication scheme using smart cards. In the same year, Chan and Cheng pointed out that Hwang and Li’s scheme is not secure against the masquerade attack. Further, in 2003, Shen, Lin and Hwang pointed out a different type of attack on Hwang and Li’s scheme and presented a modified scheme to remove its security pitfalls. This paper presents an improved scheme which is secure against Chan-Cheng and all the extended attacks. | An Improved Remote User Authentication Scheme Using Smart Cards | 7,868 |
In 2002, Chien–Jan–Tseng introduced an efficient remote user authentication scheme using smart cards. Further, in 2004, W. C. Ku and S. M. Chen proposed an efficient remote user authentication scheme using smart cards to solve the security problems of Chien et al.’s scheme. Recently, Hsu and Yoon et al. pointed out the security weakness of the Ku and Chen’s scheme Furthermore, Yoon et al. modified the password change phase of Ku and Chen’s scheme and they also proposed a new efficient remote user authentication scheme using smart cards. This paper analyzes that the modified scheme of Yoon et al. still vulnerable to parallel session attack. | The Modified Scheme is still vulnerable to the parallel Session Attack | 7,869 |
Steganography is about how to send secret message covertly. And the purpose of steganalysis is to not only detect the existence of the hidden message but also extract it. So far there have been many reliable detecting methods on various steganographic algorithms, while there are few approaches that can extract the hidden information. In this paper, the difficulty of extracting hidden information, which is essentially a kind of privacy, is analyzed with information-theoretic method in the terms of unicity distance of steganographic key (abbreviated stego key). A lower bound for the unicity distance is obtained, which shows the relations between key rate, message rate, hiding capacity and difficulty of extraction. Furthermore the extracting attack to steganography is viewed as a special kind of cryptanalysis, and an effective method on recovering the stego key of popular LSB replacing steganography in spatial images is presented by combining the detecting technique of steganalysis and correlation attack of cryptanalysis together. The analysis for this method and experimental results on steganographic software ``Hide and Seek 4.1" are both accordant with the information-theoretic conclusion. | On the Unicity Distance of Stego Key | 7,870 |
In some cases, the original signer may delegate its signing power to a specified proxy group while ensuring individual accountability of each participantsigner. The proxy signature scheme that achieves such purpose is called the multi-proxy signature scheme and the signature generated by the specified proxy group is called multi-proxy signature for the original signer. Recently such scheme has been discussed by Lin et al. Lins scheme is based on partial delegation by Mambo et al. In present chapter we introduce a new multi-proxy signature scheme, which requires less computational overhead in comparison to Lin et al, and also fulfill the requirement of partial delegation with warrant simultaneously. | A Multi-proxy Signature Scheme for Partial delegation with Warrant | 7,871 |
Since 1981, when Lamport introduced the remote user authentication scheme using table, a plenty of schemes had been proposed with table and without table using. In 1993, Chang and Wu [5] introduced Remote password authentication scheme with smart cards. A number of remote authentication schemes with smart cards have been proposed since then. These schemes allow a valid user to login a remote server and access the services provided by the remote server. But still there is no scheme to authenticate the remote proxy user. In this paper we propose firstly, a protocol to authenticate a proxy user remotely using smartcards. | A New Remote User Authentication Scheme Using Smart Cards with Check
Digits | 7,872 |
Blind signature schemes enable a useful protocol that guarantee the anonymity of the participants while Signcryption offers authentication of message and confidentiality of messages at the same time and more efficiently. In this paper, we present a blind signcryption scheme that combines the functionality of blind signature and signcryption. This blind Signcryption is useful for applications that are based on anonymity untracebility and unlinkability. | An Efficient Scheme for Sensitive Message Transmission using Blind
Signcryption | 7,873 |
In 2001, Rivest et al. firstly introduced the concept of ring signatures. A ring signature is a simplified group signature without any manager. It protects the anonymity of a signer. The first scheme proposed by Rivest et al. was based on RSA cryptosystem and certificate based public key setting. The first ring signature scheme based on DLP was proposed by Abe, Ohkubo, and Suzuki. Their scheme is also based on the general certificate-based public key setting too. In 2002, Zhang and Kim proposed a new ID-based ring signature scheme using pairings. Later Lin and Wu proposed a more efficient ID-based ring signature scheme. Both these schemes have some inconsistency in computational aspect. In this paper we propose a new ID-based ring signature scheme and a proxy ring signature scheme. Both the schemes are more efficient than existing one. These schemes also take care of the inconsistencies in above two schemes. | ID-based Ring Signature and Proxy Ring Signature Schemes from Bilinear
Pairings | 7,874 |
This work presents two new construction techniques for q-ary Gossip codes from tdesigns and Traceability schemes. These Gossip codes achieve the shortest code length specified in terms of code parameters and can withstand erasures in digital fingerprinting applications. This work presents the construction of embedded Gossip codes for extending an existing Gossip code into a bigger code. It discusses the construction of concatenated codes and realisation of erasure model through concatenated codes. | Gossip Codes for Fingerprinting: Construction, Erasure Analysis and
Pirate Tracing | 7,875 |
To study how to design steganographic algorithm more efficiently, a new coding problem -- steganographic codes (abbreviated stego-codes) -- is presented in this paper. The stego-codes are defined over the field with $q(q\ge2)$ elements. Firstly a method of constructing linear stego-codes is proposed by using the direct sum of vector subspaces. And then the problem of linear stego-codes is converted to an algebraic problem by introducing the concept of $t$th dimension of vector space. And some bounds on the length of stego-codes are obtained, from which the maximum length embeddable (MLE) code is brought up. It is shown that there is a corresponding relation between MLE codes and perfect error-correcting codes. Furthermore the classification of all MLE codes and a lower bound on the number of binary MLE codes are obtained based on the corresponding results on perfect codes. Finally hiding redundancy is defined to value the performance of stego-codes. | Steganographic Codes -- a New Problem of Coding Theory | 7,876 |
To remove key escrow problem and avoid the need of secure channel in ID based cryptosystem Lee et al. proposed a secure key issuing protocol. However we show that it suffers from impersonation, insider attacks and incompetency of the key privacy authorities. We also cryptanalyze Sui et al.'s separable and anonymous key issuing protocol. | Cryptanalysis of Key Issuing Protocols in ID-based Cryptosystems | 7,877 |
The recent developments in the mobile technology (mobile phones, middleware) created a need for new methods of protecting the code transmitted through the network. The proposed mechanisms not only secure the compiled program, but also the data, that can be gathered during its "journey". The oldest and the simplest methods are more concentrated on integrity of the code itself and on the detection of unauthorized manipulation. Other, more advanced proposals protect not only the code but also the execution state and the collected data. The paper is divided into two parts. The first one is mostly devoted to different methods of securing the code and protecting its integrity; starting from watermarking and fingerprinting, up to methods designed specially for mobile agent systems: encrypted function, cryptographic traces, time limited black-box security, chained-MAC protocol, publicly-verifiable chained digital signatures The second part presents new concept for providing mobile agents with integrity protection, based on a zero-knowledge proof system. | Security of mobile agents: a new concept of the integrity protection | 7,878 |
Some protected password change protocols were proposed. However, the previous protocols were easily vulnerable to several attacks such as denial of service, password guessing, stolen-verifier and impersonation atacks etc. Recently, Chang et al. proposed a simple authenticated key agreement and protected password change protocol for enhancing the security and efficiency. In this paper, authors shall show that password guessing, denial of service and known-key attacks can work in their password change protocol. At the same time, authors shall propose a new password change protocol to withstand all the threats of security. | A protected password change protocol | 7,879 |
Identity Management is becoming more and more important in business systems as they are opened for third parties including trading partners, consumers and suppliers. This paper presents an approach securing a system without any knowledge of the system source code. The security module adds to the existing system authentication and authorisation based on aspect oriented programming and the liberty alliance framework, an upcoming industrie standard providing single sign on. In an initial training phase the module is adapted to the application which is to be secured. Moreover the use of hardware tokens and proactive computing is demonstrated. The high modularisation is achived through use of AspectJ, a programming language extension of Java. | Security for Distributed Web-Applications via Aspect-Oriented
Programming | 7,880 |
Copyright protection is a major issue in distributing digital content. On the other hand, improvements to usability are sought by content users. In this paper, we propose a secure {\it traitor tracing scheme against key exposure (TTaKE)} which contains the properties of both a traitor tracing scheme and a forward secure public key cryptosystem. Its structure fits current digital broadcasting systems and it may be useful in preventing traitors from making illegal decoders and in minimizing the damage from accidental key exposure. It can improve usability through these properties. | A Secure Traitor Tracing Scheme against Key Exposure | 7,881 |
In 1949, Shannon proved the perfect secrecy of the Vernam cryptographic system,also popularly known as the One-Time Pad (OTP). Since then, it has been believed that the perfectly random and uncompressible OTP which is transmitted needs to have a length equal to the message length for this result to be true. In this paper, we prove that the length of the transmitted OTP which actually contains useful information need not be compromised and could be less than the message length without sacrificing perfect secrecy. We also provide a new interpretation for the OTP encryption by treating the message bits as making True/False statements about the pad, which we define as a private-object. We introduce the paradigm of private-object cryptography where messages are transmitted by verifying statements about a secret-object. We conclude by suggesting the use of Formal Axiomatic Systems for investing N bits of secret. | Re-visiting the One-Time Pad | 7,882 |
In this document, a formal approach to encrypt, decrypt, transmit and receive information using colors is explored. A piece of information consists of set of symbols with a definite property imposed on the generating set. The symbols are usually encoded using ascii scheme. A linear to 3d transformation is presented. The change of axis from traditional xyz to rgb is highlighted and its effect are studied. A point in this new axis is then represented as a unique color and a vector or matrix is associated with it, making it amenable to standard vector or matrix operations. A formal notion on hybrid cryptography is introduced as the algorithm lies on the boundary of symmetric and asymmetric cryptography. No discussion is complete, without mentioning reference to communication aspects of secure information in a channel. Transmission scheme pertaining to light as carrier is introduced and studied. Key-exchanges do not come under the scope of current frame of document. | A 3D RGB Axis-based Color-oriented Cryptography | 7,883 |
In this paper, facts existing in different domains are explored, which are comparable by their end result. Properties of various domains and the facts that are part of such a unit are also presented, examples of comparison and methods of usage as means of zero-knowledge protocols are given, finally a zero-knowledge protocol based on afore-mentioned concept is given. | ZEUS - A Domain-Oriented Fact Comparison Based Authentication Protocol | 7,884 |
In this paper we try to unify the frameworks of definitions of semantic security, indistinguishability and non-malleability by defining semantic security in comparison based framework. This facilitates the study of relations among these goals against different attack models and makes the proof of the equivalence of semantic security and indistinguishability easier and more understandable. Besides, our proof of the equivalence of semantic security and indistinguishability does not need any intermediate goals such as non devidability to change the definition framework. | Relations between semantic security and indistinguishability against
cpa, non-adaptive cca and adaptive cca in comparison based framework | 7,885 |
A first multi-proxy multi-signcryption scheme from pairings, which efficiently combines a multi-proxy multi-signature scheme with a signcryption, is proposed. Its security is analyzed in detail. In our scheme, a proxy signcrypter group could be authorized as a proxy agent by the cooperation of all members in the original signcrypter group. Then the proxy signcryptions can be generated by the cooperation of all the signcrypters in the authorized proxy signcrypter group on behalf of the original signcrypter group. The correctness and the security of this scheme are proved. | Multi-Proxy Multi-Signcryption Scheme from Pairings | 7,886 |
We propose four different identification schemes that make use of bilinear pairings, and prove their security under certain computational assumptions. Each of the schemes is more efficient and/or more secure than any known pairing-based identification scheme. | Pairing-based identification schemes | 7,887 |
Lal and Chaturvedi proposed two authentication schemes based on the difficulty of the Root Problem in the braid group. We point out that the first scheme is not really as secure as the Root Problem, and describe an efficient way to crack it. The attack works for any group. | On an authentication scheme based on the Root Problem in the braid group | 7,888 |
This report presents a taxonomy of vulnerabilities created as a part of an effort to develop a framework for deriving verification and validation strategies to assess software security. This taxonomy is grounded in a theoretical model of computing, which establishes the relationship between vulnerabilities, software applications and the computer system resources. This relationship illustrates that a software application is exploited by violating constraints imposed by computer system resources and assumptions made about their usage. In other words, a vulnerability exists in the software application if it allows violation of these constraints and assumptions. The taxonomy classifies these constraints and assumptions. The model also serves as a basis for the classification scheme the taxonomy uses, in which the computer system resources such as, memory, input/output, and cryptographic resources serve as categories and subcategories. Vulnerabilities, which are expressed in the form of constraints and assumptions, are classified according to these categories and subcategories. This taxonomy is both novel and distinctively different from other taxonomies found in the literature. | On Vulnerabilities, Constraints and Assumptions | 7,889 |
In this paper, we present a variant of Waters' Identity-Based Encryption scheme with a much smaller public-key size (only a few kilobytes). We show that this variant is semantically secure against passive adversaries in the standard model.\smallskip In essence, the new scheme divides Waters' public key size by a factor $\ell$ at the cost of (negligibly) reducing security by $\ell$ bits. Therefore, our construction settles an open question asked by Waters and constitutes the first fully secure {\sl practical} Identity-Based Encryption scheme | Secure and {\sl Practical} Identity-Based Encryption | 7,890 |
We present Poseidon, a new anomaly based intrusion detection system. Poseidon is payload-based, and presents a two-tier architecture: the first stage consists of a Self-Organizing Map, while the second one is a modified PAYL system. Our benchmarks on the 1999 DARPA data set show a higher detection rate and lower number of false positives than PAYL and PHAD. | Poseidon: a 2-tier Anomaly-based Intrusion Detection System | 7,891 |
Many computer-based authentication schemata are based on pass- words. Logging on a computer, reading email, accessing content on a web server are all examples of applications where the identification of the user is usually accomplished matching the data provided by the user with data known by the application. Such a widespread approach relies on some assumptions, whose satisfaction is of foremost importance to guarantee the robustness of the solution. Some of these assumptions, like having a "secure" chan- nel to transmit data, or having sound algorithms to check the correct- ness of the data, are not addressed by this paper. We will focus on two simple issues: the problem of using adequate passwords and the problem of managing passwords. The proposed solution, the pathword, is a method that guarantees: 1 that the passwords generated with the help of a pathword are adequate (i.e. that they are not easy to guess), 2 that managing pathwords is more user friendly than managing passwords and that pathwords are less amenable to problems typical of passwords. | Pathwords: a user-friendly schema for common passwords management | 7,892 |
To resist algebraic attack, a Boolean function should possess good algebraic immunity (AI). Several papers constructed symmetric functions with the maximum algebraic immunity $\lceil \frac{n}{2}\rceil $. In this correspondence we prove that for each odd $n$, there is exactly one trivial balanced $n$-variable symmetric Boolean function achieving the algebraic immunity $\lceil \frac{n}{2}\rceil $. And we also obtain a necessary condition for the algebraic normal form of a symmetric Boolean function with maximum algebraic immunity. | Symmetric Boolean Function with Maximum Algebraic Immunity on Odd Number
of Variables | 7,893 |
A fast algorithm is presented for determining the linear complexity and the minimal polynomial of periodic sequences over GF(q) with period q n p m, where p is a prime, q is a prime and a primitive root modulo p2. The algorithm presented here generalizes both the algorithm in [4] where the period of a sequence over GF(q) is p m and the algorithm in [5] where the period of a binary sequence is 2 n p m . When m=0, the algorithm simplifies the generalized Games-Chan algorithm. | A fast algorithm for determining the linear complexity of periodic
sequences | 7,894 |
Based on the definition of generalized partially bent functions, using the theory of linear transformation, the relationship among generalized partially bent functions over ring Z N, generalized bent functions over ring Z N and affine functions is discussed. When N is a prime number, it is proved that a generalized partially bent function can be decomposed as the addition of a generalized bent function and an affine function. The result obtained here generalizes the main works concerning partially bent functions by Claud Carlet in [1]. | Generalized partially bent functions | 7,895 |
In this paper we propose a multi-map orbit hopping chaotic stream cipher that utilizes the idea of spread spectrum mechanism for secure digital communications and fundamental chaos characteristics of mixing, unpredictable, and extremely sensitive to initial conditions. The design, key and subkeys, and detail implementation of the system are addressed. A variable number of well studied chaotic maps form a map bank. And the key determines how the system hops between multiple orbits, and it also determines the number of maps, the number of orbits for each map, and the number of sample points for each orbits. A detailed example is provided. | Multi-Map Orbit Hopping Chaotic Stream Cipher | 7,896 |
Let $\underline{a}$ be an \textit{l}-sequence generated by a feedback-with-carry shift register with connection integer $q=p^{e}$, where $ p$ is an odd prime and $e\geq 1$. Goresky and Klapper conjectured that when $ p^{e}\notin \{5,9,11,13\}$, all decimations of $\underline{a}$ are cyclically distinct. When $e=1$ and $p>13$, they showed that the set of distinct decimations is large and, in some cases, all deciamtions are distinct. In this article, we further show that when $e\geq 2$ and$ p^{e}\neq 9$, all decimations of $\underline{a}$ are also cyclically distinct. | Further Results on the Distinctness of Decimations of l-sequences | 7,897 |
Artin's braid groups have been recently suggested as a new source for public-key cryptography. In this paper we propose the first undeniable signature schemes using the conjugacy problem and the decomposition problem in the braid groups which are believed to be hard problems. | Undeniable Signature Schemes Using Braid Groups | 7,898 |
We describe a novel way in which students can learn the cipher systems without much supervision. In this work we focus on learning symmetric ciphers by altering them using the agile development approach. Two agile approaches the eXtreme Programming (XP) and the closely related Test-Driven Development (TDD) are mentioned or discussed. To facilitate this development we experiment with an approach that is based on refactoring, with JUnit serves as the automatic testing framework. In this work we exemplify our learning approach by test-infecting the Vernam cipher, an aged but still widely used stream cipher. One can replace the cipher with another symmetric cipher with the same behavior. Software testing is briefly described. Just-in-time introduction to Object-oriented programming (OOP), exemplified by using JavaTM, is advocated. Refactoring exercises, as argued, are kept strategically simple so that they do not become intensive class redesign exercises. The use of free or open-source tools and frameworks is mentioned. | Learning by Test-infecting Symmetric Ciphers | 7,899 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.