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In the UNIX/Linux environment the kernel can log every command process created by every user using process accounting. This data has many potential uses, including the investigation of security incidents. However, process accounting data is also sensitive since it contains private user information. Consequently, security system administrators have been hindered from sharing these logs. Given that many interesting security applications could use process accounting data, it would be useful to have a tool that could protect private user information in the logs. For this reason we introduce SCRUB-PA, a tool that uses multi-level multi-dimensional anonymization on process accounting log files in order to provide different levels of privacy protection. It is our goal that SCRUB-PA will promote the sharing of process accounting logs while preserving privacy. | SCRUB-PA: A Multi-Level Multi-Dimensional Anonymization Tool for Process
Accounting | 7,900 |
This paper introduces the use of decimal sequences in a code division multiple access (CDMA) based watermarking system to hide information for authentication in black and white images. Matlab version 6.5 was used to implement the algorithms discussed in this paper. The advantage of using d-sequences over PN sequences is that one can choose from a variety of prime numbers which provides a more flexible system. | Watermarking Using Decimal Sequences | 7,901 |
The paper develops a novel approach to stream cipher design: Both the state update function and the output function of the corresponding pseudorandom generators are compositions of arithmetic and bitwise logical operations, which are standard instructions of modern microprocessors. Moreover, both the state update function and the output function are being modified dynamically during the encryption. Also, these compositions could be keyed, so the only information available to an attacker is that these functions belong to some exponentially large class. The paper shows that under rather loose conditions the output sequence is uniformly distributed, achieves maximum period length and has high linear complexity and high $\ell$-error linear complexity. Ciphers of this kind are flexible: One could choose a suitable combination of instructions to obtain due performance without affecting the quality of the output sequence. Finally, some evidence is given that a key recovery problem for (reasonably designed) stream ciphers of this kind is intractable up to plausible conjectures. | Wreath Products in Stream Cipher Design | 7,902 |
The paper analyzes a new public key cryptosystem whose security is based on a matrix version of the discrete logarithm problem over an elliptic curve. It is shown that the complexity of solving the underlying problem for the proposed system is dominated by the complexity of solving a fixed number of discrete logarithm problems in the group of an elliptic curve. Using an adapted Pollard rho algorithm it is shown that this problem is essentially as hard as solving one discrete logarithm problem in the group of an elliptic curve. | Cryptanalysis of the CFVZ cryptosystem | 7,903 |
Artin's braid groups have been recently suggested as a new source for public-key cryptography. In this paper we propose the first group signature schemes based on the conjugacy problem, decomposition problem and root problem in the braid groups which are believed to be hard problems. | Group Signature Schemes Using Braid Groups | 7,904 |
We propose the use of the cubic transformation for public-key applications and digital signatures. Transformations modulo a prime p or a composite n=pq, where p and q are primes, are used in such a fashion that each transformed value has only 3 roots that makes it a more efficient transformation than the squaring transformation of Rabin, which has 4 roots. Such a transformation, together with additional tag information, makes it possible to uniquely invert each transformed value. The method may be used for other exponents as well. | The Cubic Public-Key Transformation | 7,905 |
The established techniques for legal-for-trade registration of weight values meet the legal requirements, but in praxis they show serious disadvantages. We report on the first implementation of intrinsically legal-for-trade objects, namely weight values signed by the scale, that is accepted by the approval authority. The strict requirements from both the approval- and the verification-authority as well as the limitations due to the hardware of the scale were a special challenge. The presented solution fulfills all legal requirements and eliminates the existing practical disadvantages. | Intrinsically Legal-For-Trade Objects by Digital Signatures | 7,906 |
Significant research has been done in the area of Role Based Access Control [RBAC]. Within this research there has been a thread of work focusing on adding parameters to the role and permissions within RBAC. The primary benefit of parameter support in RBAC comes in the form of a significant increase in specificity in how permissions may be granted. This paper focuses on implementing a parameterized implementation based heavily upon existing standards. | A Service-Centric Approach to a Parameterized RBAC Service | 7,907 |
This paper analyzes the performance of Kak's three stage quantum cryptographic protocol based on public key cryptography against a man-in-the-middle attack. A method for protecting against such an attack is presented using certificates distributed by a trusted third party. | Trusted Certificates in Quantum Cryptography | 7,908 |
Horizontal integration of access technologies to networks and services should be accompanied by some kind of convergence of authentication technologies. The missing link for the federation of user identities across the technological boundaries separating authentication methods can be provided by trusted computing platforms. The concept of establishing transitive trust by trusted computing enables the desired crossdomain authentication functionality. The focus of target application scenarios lies in the realm of mobile networks and devices. | Transitive trust in mobile scenarios | 7,909 |
This paper presents watermarking algorithms using d-sequences so that the peak signal to noise ratio (PSNR) is maximized and the distortion introduced in the image due to the embedding is minimized. By exploiting the cross correlation property of decimal sequences, the concept of embedding more than one watermark in the same cover image is investigated. | Improved Watermarking Scheme Using Decimal Sequences | 7,910 |
Basic role based access control [RBAC] provides a mechanism for segregating access privileges based upon a user's hierarchical roles within an organization. This model doesn't scale well when there is tight integration of multiple hierarchies. In a case where there is joint-tenancy and a requirement for different levels of disclosure based upon a user's hierarchy, or in our case, organization or company, basic RBAC requires these hierarchies to be effectively merged. Specific roles that effectively represent both the user's organizations and roles must be translated to fit within the merged hierarchy to be used to control access. Essentially, users from multiple organizations are served from a single role base with roles designed to constrain their access as needed. Our work proposes, through parameterized roles and privileges, a means for accurately representing both users' roles within their respective hierarchies for providing access to controlled objects. Using this method will reduce the amount of complexity required in terms of the number of roles and privileges. The resulting set of roles, privileges, and objects will make modeling and visualizing the access role hierarchy significantly simplified. This paper will give some background on role based access control, parameterized roles and privileges, and then focus on how RBAC with parameterized roles and privileges can be leveraged as an access control solution for the problems presented by joint tenancy. | Access Control for Hierarchical Joint-Tenancy | 7,911 |
In this paper we present an approach for specifying and prioritizing information security requirements in organizations. It is important to prioritize security requirements since hundred per cent security is not achievable and the limited resources available should be directed to satisfy the most important ones. We propose to link explicitly security requirements with the organization's business vision, i.e. to provide business rationale for security requirements. The rationale is then used as a basis for comparing the importance of different security requirements. A conceptual framework is presented, where the relationships between business vision, critical impact factors and valuable assets (together with their security requirements) are shown. | A Business Goal Driven Approach for Understanding and Specifying
Information Security Requirements | 7,912 |
This paper presents an introduction to the Aryabhata algorithm for finding multiplicative inverses and solving linear congruences, both of which have applications in cryptography. We do so by the use of the least absolute remainders. The exposition of the Aryabhata algorithm provided here can have performance that could exceed what was described recently by Rao and Yang. | The Aryabhata Algorithm Using Least Absolute Remainders | 7,913 |
We present APHRODITE, an architecture designed to reduce false positives in network intrusion detection systems. APHRODITE works by detecting anomalies in the output traffic, and by correlating them with the alerts raised by the NIDS working on the input traffic. Benchmarks show a substantial reduction of false positives and that APHRODITE is effective also after a "quick setup", i.e. in the realistic case in which it has not been "trained" and set up optimally | APHRODITE: an Anomaly-based Architecture for False Positive Reduction | 7,914 |
This paper explains the recent developments in security and encryption. The Butterfly cipher and quantum cryptography are reviewed and compared. Examples of their relative uses are discussed and suggestions for future developments considered. In addition application to network security together with a substantial review of classification of encryption systems and a summary of security weaknesses are considered. | Will the Butterfly Cipher keep your Network Data secure? Developments in
Computer Encryption | 7,915 |
After a brief introduction to a new chaotic stream cipher Mmohocc which utilizes the fundamental chaos characteristics of mixing, unpredictability, and sensitivity to initial conditions, we conducted the randomness statistical tests against the keystreams generated by the cipher. Two batteries of most stringent randomness tests, namely the NIST Suite and the Diehard Suite, were performed. The results showed that the keystreams have successfully passed all the statistical tests. We conclude that Mmohocc can generate high-quality pseudorandom numbers from a statistical point of view. | A Chaotic Cipher Mmohocc and Its Randomness Evaluation | 7,916 |
This paper modifies Kak's three-stage protocol so that it can guarantee secure transmission of information. Although avoiding man-in-the-middle attack is our primary objective in the introduction of classical authentication inside the three-stage protocol, we also benefit from the inherent advantages of the chosen classical authentication protocol. We have tried to implement ideas like key distribution center, session key, time-stamp, and nonce, within the quantum cryptography protocol. | Classical Authentication Aided Three-Stage Quantum Protocol | 7,917 |
We introduce knowledge flow analysis, a simple and flexible formalism for checking cryptographic protocols. Knowledge flows provide a uniform language for expressing the actions of principals, assump- tions about intruders, and the properties of cryptographic primitives. Our approach enables a generalized two-phase analysis: we extend the two-phase theory by identifying the necessary and sufficient proper- ties of a broad class of cryptographic primitives for which the theory holds. We also contribute a library of standard primitives and show that they satisfy our criteria. | A Generalized Two-Phase Analysis of Knowledge Flows in Security
Protocols | 7,918 |
One improves an algebraic attack of NTRU due to Silverman, Smart and Vercauteren; the latter considered the first 2 bits of a Witt vector attached to the research of the secret key; here the first 4 bits are considered, which provides additional equations of degrees 4 and 8. | Attaque algebrique de NTRU a l'aide des vecteurs de Witt | 7,919 |
Algebraic immunity has been proposed as an important property of Boolean functions. To resist algebraic attack, a Boolean function should possess high algebraic immunity. It is well known now that the algebraic immunity of an $n$-variable Boolean function is upper bounded by $\left\lceil {\frac{n}{2}} \right\rceil $. In this paper, for an odd integer $n$, we present a construction method which can efficiently generate a Boolean function of $n$ variables with maximum algebraic immunity, and we also show that any such function can be generated by this method. Moreover, the number of such Boolean functions is greater than $2^{2^{n-1}}$. | Construction and Count of Boolean Functions of an Odd Number of
Variables with Maximum Algebraic Immunity | 7,920 |
In this paper we introduce a new chaotic stream cipher Mmohocc which utilizes the fundamental chaos characteristics. The designs of the major components of the cipher are given. Its cryptographic properties of period, auto- and cross-correlations, and the mixture of Markov processes and spatiotemporal effects are investigated. The cipher is resistant to the related-key-IV attacks, Time/Memory/Data tradeoff attacks, algebraic attacks, and chosen-text attacks. The keystreams successfully passed two batteries of statistical tests and the encryption speed is comparable with RC4. | A Chaotic Cipher Mmohocc and Its Security Analysis | 7,921 |
Although good encryption functions are probabilistic, most symbolic models do not capture this aspect explicitly. A typical solution, recently used to prove the soundness of such models with respect to computational ones, is to explicitly represent the dependency of ciphertexts on random coins as labels. In order to make these label-based models useful, it seems natural to try to extend the underlying decision procedures and the implementation of existing tools. In this paper we put forth a more practical alternative based on the following soundness theorem. We prove that for a large class of security properties (that includes rather standard formulations for secrecy and authenticity properties), security of protocols in the simpler model implies security in the label-based model. Combined with the soundness result of (\textbf{?}) our theorem enables the translation of security results in unlabeled symbolic models to computational security. | Explicit Randomness is not Necessary when Modeling Probabilistic
Encryption | 7,922 |
An efficient archive securing the integrity of VoIP-based two-party conversations is presented. The solution is based on chains of hashes and continuously chained electronic signatures. Security is concentrated in a single, efficient component, allowing for a detailed analysis. | A secure archive for Voice-over-IP conversations | 7,923 |
Due to the convergence of various mobile access technologies like UMTS, WLAN, and WiMax the need for a new supporting infrastructure arises. This infrastructure should be able to support more efficient ways to authenticate users and devices, potentially enabling novel services based on the security provided by the infrastructure. In this paper we exhibit some usage scenarios from the mobile domain integrating trusted computing, which show that trusted computing offers new paradigms for implementing trust and by this enables new technical applications and business scenarios. The scenarios show how the traditional boundaries between technical and authentication domains become permeable while a high security level is maintained. | Trusted Computing in Mobile Action | 7,924 |
FLAIM (Framework for Log Anonymization and Information Management) addresses two important needs not well addressed by current log anonymizers. First, it is extremely modular and not tied to the specific log being anonymized. Second, it supports multi-level anonymization, allowing system administrators to make fine-grained trade-offs between information loss and privacy/security concerns. In this paper, we examine anonymization solutions to date and note the above limitations in each. We further describe how FLAIM addresses these problems, and we describe FLAIM's architecture and features in detail. | FLAIM: A Multi-level Anonymization Framework for Computer and Network
Logs | 7,925 |
We present a concept to achieve non-repudiation for natural language conversations by electronically signing packet-based, digital, voice communication. Signing a VoIP-based conversation means to protect the integrity and authenticity of the bidirectional data stream and its temporal sequence which together establish the security context of the communication. Our concept is conceptually close to the protocols that embody VoIP and provides a high level of inherent security. It enables signatures over voice as true declarations of will, in principle between unacquainted speakers. We point to trusted computing enabled devices as possible trusted signature terminals for voice communication. | Security and Non-Repudiation for Voice-Over-IP Conversations | 7,926 |
We propose a simple universal (that is, distribution--free) steganographic system in which covertexts with and without hidden texts are statistically indistinguishable. The stegosystem can be applied to any source generating i.i.d. covertexts with unknown distribution, and the hidden text is transmitted exactly, with zero probability of error. Moreover, the proposed steganographic system has two important properties. First, the rate of transmission of hidden information approaches the Shannon entropy of the covertext source as the size of blocks used for hidden text encoding tends to infinity. Second, if the size of the alphabet of the covertext source and its minentropy tend to infinity then the number of bits of hidden text per letter of covertext tends to $\log(n!)/n$ where $n$ is the (fixed) size of blocks used for hidden text encoding. The proposed stegosystem uses randomization. | Provably Secure Universal Steganographic Systems | 7,927 |
In this paper we resolve an open problem regarding resettable zero knowledge in the bare public-key (BPK for short) model: Does there exist constant round resettable zero knowledge argument with concurrent soundness for $\mathcal{NP}$ in BPK model without assuming \emph{sub-exponential hardness}? We give a positive answer to this question by presenting such a protocol for any language in $\mathcal{NP}$ in the bare public-key model assuming only collision-resistant hash functions against \emph{polynomial-time} adversaries. | Resettable Zero Knowledge in the Bare Public-Key Model under Standard
Assumption | 7,928 |
Source data for computer network security analysis takes different forms (alerts, incidents, logs) and each source may be voluminous. Due to the challenge this presents for data management, this has often lead to security stovepipe operations which focus primarily on a small number of data sources for analysis with little or no automated correlation between data sources (although correlation may be done manually). We seek to address this systemic problem. In previous work we developed a unified correlated logging system (UCLog) that automatically processes alerts from different devices. We take this work one step further by presenting the architecture and applications of UCLog+ which adds the new capability to correlate between alerts and incidents and raw data located on remote logs. UCLog+ can be used for forensic analysis including queries and report generation but more importantly it can be used for near-real-time situational awareness of attack patterns in progress. The system, implemented with open source tools, can also be a repository for secure information sharing by different organizations. | UCLog+ : A Security Data Management System for Correlating Alerts,
Incidents, and Raw Data From Remote Logs | 7,929 |
We review the fingerprinting scheme by Tardos and show that it has a much better performance than suggested by the proofs in Tardos' original paper. In particular, the length of the codewords can be significantly reduced. First we generalize the proofs of the false positive and false negative error probabilities with the following modifications: (1) we replace Tardos' hard-coded numbers by variables and (2) we allow for independently chosen false positive and false negative error rates. It turns out that all the collusion-resistance properties can still be proven when the code length is reduced by a factor of more than 2. Second, we study the statistical properties of the fingerprinting scheme, in particular the average and variance of the accusations. We identify which colluder strategy forces the content owner to employ the longest code. Using a gaussian approximation for the probability density functions of the accusations, we show that the required false negative and false positive error rate can be achieved with codes that are a factor 2 shorter than required for rigid proofs. Combining the results of these two approaches, we show that the Tardos scheme can be used with a code length approximately 5 times shorter than in the original construction. | Tardos fingerprinting is better than we thought | 7,930 |
Reputation and recommendation systems are fundamental for the formation of community market places. Yet, they are easy targets for attacks which disturb a market's equilibrium and are often based on cheap pseudonyms used to submit ratings. We present a method to price ratings using trusted computing, based on pseudonymous tickets. | Employing Trusted Computing for the forward pricing of pseudonyms in
reputation systems | 7,931 |
McLean's notion of Selective Interleaving Functions (SIFs) is perhaps the best-known attempt to construct a framework for expressing various security properties. We examine the expressive power of SIFs carefully. We show that SIFs cannot capture nondeducibility on strategies (NOS). We also prove that the set of security properties expressed with SIFs is not closed under conjunction, from which it follows that separability is strictly stronger than double generalized noninterference. However, we show that if we generalize the notion of SIF in a natural way, then NOS is expressible, and the set of security properties expressible by generalized SIFs is closed under conjunction. | Expressing Security Properties Using Selective Interleaving Functions | 7,932 |
With the rapid spread of various mobile terminals in our society, the importance of secure positioning is growing for wireless networks in adversarial settings. Recently, several authors have proposed a secure positioning mechanism of mobile terminals which is based on the geometric property of wireless node placement, and on the postulate of modern physics that a propagation speed of information never exceeds the velocity of light. In particular, they utilize the measurements of the round-trip time of radio signal propagation and bidirectional communication for variants of the challenge-and-response. In this paper, we propose a novel means to construct the above mechanism by use of unidirectional communication instead of bidirectional communication. Our proposal is based on the assumption that a mobile terminal incorporates a high-precision inner clock in a tamper-resistant protected area. In positioning, the mobile terminal uses its inner clock and the time and location information broadcasted by radio from trusted stations. Our proposal has a major advantage in protecting the location privacy of mobile terminal users, because the mobile terminal need not provide any information to the trusted stations through positioning procedures. Besides, our proposal is free from the positioning error due to claimant's processing-time fluctuations in the challenge-and-response, and is well-suited for mobile terminals in the open air, or on the move at high speed, in terms of practical usage. We analyze the security, the functionality, and the feasibility of our proposal in comparison to previous proposals. | Secure Positioning of Mobile Terminals with Simplex Radio Communication | 7,933 |
Technical security is only part of E-Commerce security operations; human usability and security perception play major and sometimes dominating factors. For instance, slick websites with impressive security icons but no real technical security are often perceived by users to be trustworthy (and thus more profitable) than plain vanilla websites that use powerful encryption for transmission and server protection. We study one important type of E-Commerce transaction website, E-Tax Filing, that is exposed to large populations. We assess a large number of international (5), Federal (USA), and state E-Tax filing websites (38) for both technical security protection and human perception of security. As a result of this assessment, we identify security best practices across these E-Tax Filing websites and recommend additional security techniques that have not been found in current use by E-Tax Filing websites. | Security Assessment of E-Tax Filing Websites | 7,934 |
For a secret sharing scheme, two parameters $d_{min}$ and $d_{cheat}$ are defined in [12] and [13]. These two parameters measure the error-correcting capability and the secret-recovering capability of the secret sharing scheme against cheaters. Some general properties of the parameters have been studied in [12,[9] and [13]. The MDS secret-sharing scheme was defined in [12] and it is proved that MDS perfect secret sharing scheme can be constructed for any monotone access structure. The famous Shamir $(k,n)$ threshold secret sharing scheme is the MDS with $d_{min}=d_{cheat}=n-k+1$. In [3] we proposed the linear secret sharing scheme from algebraic-geometric codes. In this paper the linear secret sharing scheme from AG-codes on elliptic curves is studied and it is shown that many of them are MDS linear secret sharing scheme. | MDS Ideal Secret Sharing Scheme from AG-codes on Elliptic Curves | 7,935 |
Oblivious transfer is a primitive of paramount importance in cryptography or, more precisely, two- and multi-party computation due to its universality. Unfortunately, oblivious transfer cannot be achieved in an unconditionally secure way for both parties from scratch. Therefore, it is a natural question what information-theoretic primitives or computational assumptions oblivious transfer can be based on. The results in our thesis are threefold. First, we present a protocol that implements oblivious transfer from a weakened oblivious transfer called universal oblivious transfer, where one of the two players may get additional information. Our reduction is about twice as efficient as previous results. Weak oblivious transfer is an even weaker form of oblivious transfer, where both players may obtain additional information about the other player's input, and where the output can contain errors. We give a new, weaker definition of weak oblivious transfer, as well as new reductions with a more detailed analysis. Finally, we carry over our results to the computational setting and show how a weak oblivious transfer that is sometimes incorrect and only mildly secure against computationally bounded adversaries can be strengthened. | Oblivious-Transfer Amplification | 7,936 |
From the motivation of algebraic attacks to stream and block ciphers([1,2,7,13,14,15]), the concept of {\em algebraic immunity} (AI) was introduced in [21] and studied in [3,5,10,11,17,18,19,20,21]. High algebraic immunity is a necessary condition for resisting algebraic attacks. In this paper, we give some lower bounds on algebraic immunity of Boolean functions. The results are applied to give lower bounds on AI of symmetric Boolean functions and rotation symmetric Boolean functions. Some balanced rotation symmetric Boolean functions with their AI near the maximum possible value $\lceil \frac{n}{2}\rceil$ are constructed. | Lower Bounds on the Algebraic Immunity of Boolean Functions | 7,937 |
This paper presents a robust and transparent scheme of watermarking that exploits the human visual systems' sensitivity to frequency, along with local image characteristics obtained from the spatial domain. The underlying idea is generating a visual mask based on the visual systems' perception of image content. This mask is used to embed a decimal sequence while keeping its amplitude below the distortion sensitivity of the image pixel. We consider texture, luminance, corner and the edge information in the image to generate a mask that makes the addition of the watermark imperceptible to the human eye. | Improved Content Based Image Watermarking | 7,938 |
We consider a type of zero-knowledge protocols that are of interest for their practical applications within networks like the Internet: efficient zero-knowledge arguments of knowledge that remain secure against concurrent man-in-the-middle attacks. In an effort to reduce the setup assumptions required for efficient zero-knowledge arguments of knowledge that remain secure against concurrent man-in-the-middle attacks, we consider a model, which we call the Authenticated Public-Key (APK) model. The APK model seems to significantly reduce the setup assumptions made by the CRS model (as no trusted party or honest execution of a centralized algorithm are required), and can be seen as a slightly stronger variation of the Bare Public-Key (BPK) model from \cite{CGGM,MR}, and a weaker variation of the registered public-key model used in \cite{BCNP}. We then define and study man-in-the-middle attacks in the APK model. Our main result is a constant-round concurrent non-malleable zero-knowledge argument of knowledge for any polynomial-time relation (associated to a language in $\mathcal{NP}$), under the (minimal) assumption of the existence of a one-way function family. Furthermore,We show time-efficient instantiations of our protocol based on known number-theoretic assumptions. We also note a negative result with respect to further reducing the setup assumptions of our protocol to those in the (unauthenticated) BPK model, by showing that concurrently non-malleable zero-knowledge arguments of knowledge in the BPK model are only possible for trivial languages. | Concurrently Non-Malleable Zero Knowledge in the Authenticated
Public-Key Model | 7,939 |
Conjugacy is not the only possible primitive for designing braid-based protocols. To illustrate this principle, we describe a Fiat--Shamir-style authentication protocol that be can be implemented using any binary operation that satisfies the left self-distributive law. Conjugation is an example of such an operation, but there are other examples, in particular the shifted conjugation on Artin's braid group B\_oo, and the finite Laver tables. In both cases, the underlying structures have a high combinatorial complexity, and they lead to difficult problems. | Using shifted conjugacy in braid-based cryptography | 7,940 |
We consider the problem of private computation of approximate Heavy Hitters. Alice and Bob each hold a vector and, in the vector sum, they want to find the B largest values along with their indices. While the exact problem requires linear communication, protocols in the literature solve this problem approximately using polynomial computation time, polylogarithmic communication, and constantly many rounds. We show how to solve the problem privately with comparable cost, in the sense that nothing is learned by Alice and Bob beyond what is implied by their input, the ideal top-B output, and goodness of approximation (equivalently, the Euclidean norm of the vector sum). We give lower bounds showing that the Euclidean norm must leak by any efficient algorithm. | Private Approximate Heavy Hitters | 7,941 |
In this paper, we propose a unification algorithm for the theory $E$ which combines unification algorithms for $E\_{\std}$ and $E\_{\ACUN}$ (ACUN properties, like XOR) but compared to the more general combination methods uses specific properties of the equational theories for further optimizations. Our optimizations drastically reduce the number of non-deterministic choices, in particular those for variable identification and linear orderings. This is important for reducing both the runtime of the unification algorithm and the number of unifiers in the complete set of unifiers. We emphasize that obtaining a ``small'' set of unifiers is essential for the efficiency of the constraint solving procedure within which the unification algorithm is used. The method is implemented in the CL-Atse tool for security protocol analysis. | Implementing a Unification Algorithm for Protocol Analysis with XOR | 7,942 |
This paper presents a quasigroup encryptor that has very good scrambling properties. We show that the output of the encryptor maximizes the output entropy and the encrypted output for constant and random inputs is very similar. The system architecture of the quasigroup encryptor and the autocorrelation properties of the output sequences are provided. | A Quasigroup Based Cryptographic System | 7,943 |
Differential Power Analysis (DPA) presents a major challenge to mathematically-secure cryptographic protocols. Attackers can break the encryption by measuring the energy consumed in the working digital circuit. To prevent this type of attack, this paper proposes the use of reversible logic for designing the ALU of a cryptosystem. Ideally, reversible circuits dissipate zero energy. Thus, it would be of great significance to apply reversible logic to designing secure cryptosystems. As far as is known, this is the first attempt to apply reversible logic to developing secure cryptosystems. In a prototype of a reversible ALU for a crypto-processor, reversible designs of adders and Montgomery multipliers are presented. The reversible designs of a carry propagate adder, four-to-two and five-to-two carry save adders are presented using a reversible TSG gate. One of the important properties of the TSG gate is that it can work singly as a reversible full adder. In order to design the reversible Montgomery multiplier, novel reversible sequential circuits are also proposed which are integrated with the proposed adders to design a reversible modulo multiplier. It is intended that this paper will provide a starting point for developing cryptosystems secure against DPA attacks. | Reversible Logic to Cryptographic Hardware: A New Paradigm | 7,944 |
An Extended Visual Cryptography Scheme (EVCS) was proposed by Ateniese et al. [3] to protect a binary secret image with meaningful (innocent-looking) shares. This is implemented by concatenating an extended matrix to each basis matrix. The minimum size of the extended matrix was obtained from a hypergraph coloring model and the scheme was designed for binary images only [3]. In this paper, we give a more concise derivation for this matrix extension for color images. Furthermore, we present a (k, n) scheme to protect multiple color images with meaningful shares. This scheme is an extension of the (n, n) VCS for multiple binary images proposed in Droste scheme [2]. | On the Analysis and Generalization of Extended Visual Cryptography
Schemes | 7,945 |
Confidentiality, integrity and authentication are more relevant issues in Ad hoc networks than in wired fixed networks. One way to address these issues is the use of symmetric key cryptography, relying on a secret key shared by all members of the network. But establishing and maintaining such a key (also called the session key) is a non-trivial problem. We show that Group Key Agreement (GKA) protocols are suitable for establishing and maintaining such a session key in these dynamic networks. We take an existing GKA protocol, which is robust to connectivity losses and discuss all the issues for good functioning of this protocol in Ad hoc networks. We give implementation details and network parameters, which significantly reduce the computational burden of using public key cryptography in such networks. | Efficient and Dynamic Group Key Agreement in Ad hoc Networks | 7,946 |
This paper presents two attacks against Achterbahn-128/80, the last version of one of the stream cipher proposals in the eSTREAM project. The attack against the 80-bit variant, Achterbahn-80, has complexity 2^{56.32}. The attack against Achterbahn-128 requires 2^{75.4} operations and 2^{61} keystream bits. These attacks are based on an improvement of the attack due to Hell and Johansson against Achterbahn version 2 and also on an algorithm that makes profit of the short lengths of the constituent registers. ***** Ce papier pr\'{e}sente deux attaques sur Achterbahn-128/80, la derni\`{e}re version d'un des algorithmes propos\'{e}s dans le cadre de eSTREAM. L'attaque sur la version de 80 bits, Achterbahn-80, est en 2^{56.32}. L'attaque sur Achterbahn-128 a besoin de 2^{75.4} calculs et 2^{61} bits de suite chiffrante. Ces attaques sont bas\'{e}es sur une am\'{e}lioration de l'attaque propos\'{e}e par Hell et Johansson sur la version 2 d'Achterbahn et aussi sur un algorithme qui tire profit des petites longueurs des registres. | Cryptanalyse de Achterbahn-128/80 | 7,947 |
Recently, various side-channel attacks on widely used encryption methods have been discovered. Extensive research is currently undertaken to develop new types of combined encryption and authentication mechanisms. Developers of security systems ask whether to implement methods recommended by international standards or to choose one of the new proposals. We explain the nature of the attacks and how they can be avoided, and recommend a sound, provably secure solution: the CCM standard. | HowTo Authenticate and Encrypt | 7,948 |
Automatic security protocol analysis is currently feasible only for small protocols. Since larger protocols quite often are composed of many small protocols, compositional analysis is an attractive, but non-trivial approach. We have developed a framework for compositional analysis of a large class of security protocols. The framework is intended to facilitate automatic as well as manual verification of large structured security protocols. Our approach is to verify properties of component protocols in a multi-protocol environment, then deduce properties about the composed protocol. To reduce the complexity of multi-protocol verification, we introduce a notion of protocol independence and prove a number of theorems that enable analysis of independent component protocols in isolation. To illustrate the applicability of our framework to real-world protocols, we study a key establishment sequence in WiMax consisting of three subprotocols. Except for a small amount of trivial reasoning, the analysis is done using automatic tools. | A framework for compositional verification of security protocols | 7,949 |
We consider a reasonably simple voting system which can be implemented for web-based ballots. Simplicity, modularity and the requirement of compatibility with current web browsers leads to a system which satisfies a set of security requirements for a ballot system which is not complete but sufficient in many cases. Due to weak-eligibility and vote-selling, this system cannot be used for political or similar ballots. | A modular eballot system - V0.6 | 7,950 |
We present a method to secure the complete path between a server and the local human user at a network node. This is useful for scenarios like internet banking, electronic signatures, or online voting. Protection of input authenticity and output integrity and authenticity is accomplished by a combination of traditional and novel technologies, e.g., SSL, ActiveX, and DirectX. Our approach does not require administrative privileges to deploy and is hence suitable for consumer applications. Results are based on the implementation of a proof-of-concept application for the Windows platform. | Extending the Trusted Path in Client-Server Interaction | 7,951 |
In the recent years, several practical methods have been published to compute collisions on some commonly used hash functions. In this paper we present a method to take into account, at the symbolic level, that an intruder actively attacking a protocol execution may use these collision algorithms in reasonable time during the attack. Our decision procedure relies on the reduction of constraint solving for an intruder exploiting the collision properties of hush functions to constraint solving for an intruder operating on words. | A Symbolic Intruder Model for Hash-Collision Attacks | 7,952 |
Delivery of content to mobile devices gains increasing importance in industrial environments to support employees in the field. An important application are e-mail push services like the fashionable Blackberry. These systems are facing security challenges regarding data transport to, and storage of the data on the end user equipment. The emerging Trusted Computing technology offers new answers to these open questions. | Trustworthy content push | 7,953 |
This paper presents an identity based multi-proxy multi-signcryption scheme from pairings. In this scheme a proxy signcrypter group could authorized as a proxy agent by the coopration of all members in the original signcryption group. Then the proxy signcryption can be generated by the cooperation of all the signcrypters in the authorized proxy signcrypter group on the behalf of the original signcrypter group. As compared to the scheme of Liu and Xiao, the proposed scheme provides public verifiability of the signature along with simplified key management. | New ID Based Multi-Proxy Multi-Signcryption Scheme from Pairings | 7,954 |
Finding low-weight multiples of a binary polynomial is a difficult problem arising in the context of stream ciphers cryptanalysis. The classical algorithm to solve this problem is based on a time memory trade-off. We will present an improvement to this approach using discrete logarithm rather than a direct representation of the involved polynomials. This gives an algorithm which improves the theoretical complexity, and is also very flexible in practice. | Finding low-weight polynomial multiples using discrete logarithm | 7,955 |
Trusted Computing is a security base technology that will perhaps be ubiquitous in a few years in personal computers and mobile devices alike. Despite its neutrality with respect to applications, it has raised some privacy concerns. We show that trusted computing can be applied for service access control in a manner protecting users' privacy. We construct a ticket system -- a concept which is at the heart of Identity Management -- relying solely on the capabilities of the trusted platform module and the standards specified by the Trusted Computing Group. Two examples show how it can be used for pseudonymous and protected service access. | Trusted Ticket Systems and Applications | 7,956 |
We present a concept to achieve non-repudiation for natural language conversations over the Internet. The method rests on chained electronic signatures applied to pieces of packet-based, digital, voice communication. It establishes the integrity and authenticity of the bidirectional data stream and its temporal sequence and thus the security context of a conversation. The concept is close to the protocols for Voice over the Internet (VoIP), provides a high level of inherent security, and extends naturally to multilateral non-repudiation, e.g., for conferences. Signatures over conversations can become true declarations of will in analogy to electronically signed, digital documents. This enables binding verbal contracts, in principle between unacquainted speakers, and in particular without witnesses. A reference implementation of a secure VoIP archive is exhibited. | Non-Repudiation in Internet Telephony | 7,957 |
We describe a concept to employ Trusted Computing technology to secure Conditional Access Systems (CAS) for DVB. Central is the embedding of a trusted platform module (TPM) into the set-top-box or residential home gateway. Various deployment scenarios exhibit possibilities of charging co-operation with mobile network operators (MNO), or other payment providers. | Protection of DVB Systems by Trusted Computing | 7,958 |
We investigate the bit-search type irregular decimation algorithms that are used within LFSR-based stream ciphers. In particular, we concentrate on BSG and ABSG, and consider two different setups for the analysis. In the first case, the input is assumed to be a m-sequence; we show that all possible output sequences can be classified into two sets, each of which is characterized by the equivalence of their elements up to shifts. Furthermore, we prove that the cardinality of each of these sets is equal to the period of one of its elements and subsequently derive the first known bounds on the expected output period (assuming that no subperiods exist). In the second setup, we work in a probabilistic framework and assume that the input sequence is evenly distributed (i.e., independent identically distributed Bernoulli process with probability 1/2). Under these assumptions, we derive closed-form expressions for the distribution of the output length and the output rate, which is shown to be asymptotically Gaussian-distributed and concentrated around the mean with exponential tightness. | A Note on the Periodicity and the Output Rate of Bit Search Type
Generators | 7,959 |
In this letter we assert that we have reconstructed the nonlinear filter function of LILI-128 stream cipher on IBM notebook PC using MATLAB. Our reconstruction need approximately 2^12~2^13 and the attack consumes 5825.016 sec (using tic and toc sentences of MATLAB) or 5825.016/3600=1.6181hours. We got the expression of the nonlinear filter function fd of Lili-128 which has 46 items from liner items to nonlinear items based on complexity, the phase space reconstruction, Clustering and nonlinear prediction. We have verified our reconstruction result correctness by simulating the overview of Lili-128 keystream generators using our getting fd and implement designers reference module of the Lili-128 stream cipher, and two methods produce the same synchronous keystream sequence on same initial state, so that our research work proves that the nonlinear filter function of LILI-128 stream cipher is successfully reconstructed. | Reconstructing the Nonlinear Filter Function of LILI-128 Stream Cipher
Based on Complexity | 7,960 |
This paper compares the popular quantum key distribution (QKD) protocol BB84 with the more recent Kak's three-stage protocol and the latter is shown to be more secure. A theoretical representation of an authentication-aided version of Kak's three-stage protocol is provided that makes it possible to deal with the man-in-the-middle attack. | Comparing BB84 and Authentication-Aided Kak's Three-Stage Quantum
Protocol | 7,961 |
In this paper, we present a new identity-based encryption (IBE) scheme using bilinear pairings. Our IBE scheme enjoys the same \textsf{Key Extraction} and \textsf{Decryption} algorithms with the famous IBE scheme of Boneh and Franklin (BF-IBE for short), while differs from the latter in that it has modified \textsf{Setup} and \textsf{Encryption} algorithms. Compared with BF-IBE, we show that ours are more practical in a multiple private key generator (PKG) environment, mainly due to that the session secret $g_{ID}$ could be pre-computed \emph{before} any interaction, and the sender could encrypt a message using $g_{ID}$ prior to negotiating with the intended recipient(s). As an application of our IBE scheme, we also derive an escrowed ElGamal scheme which possesses certain good properties in practice. | Practical Identity-Based Encryption (IBE) in Multiple PKG Environments
and Its Applications | 7,962 |
In this paper we propose a general definition of secrecy for cryptographic protocols in the Dolev-Yao model. We give a sufficient condition ensuring secrecy for protocols where rules have encryption depth at most two, that is satisfied by almost all practical protocols. The only allowed primitives in the class of protocols we consider are pairing and encryption with atomic keys. Moreover, we describe an algorithm of practical interest which transforms a cryptographic protocol into a secure one from the point of view of secrecy, without changing its original goal with respect to secrecy of nonces and keys, provided the protocol satisfies some conditions. These conditions are not very restrictive and are satisfied for most practical protocols. | How to Guarantee Secrecy for Cryptographic Protocols | 7,963 |
We illustrate through example 1 and 2 that the condition at theorem 1 in [8] dissatisfies necessity, and the converse proposition of fact 1.1 in [8] does not hold, namely the condition Z/M - L/Ak < 1/(2 Ak^2) is not sufficient for f(i) + f(j) = f(k). Illuminate through an analysis and ex.3 that there is a logic error during deduction of fact 1.2, which causes each of fact 1.2, 1.3, 4 to be invalid. Demonstrate through ex.4 and 5 that each or the combination of qu+1 > qu * D at fact 4 and table 1 at fact 2.2 is not sufficient for f(i) + f(j) = f(k), property 1, 2, 3, 4, 5 each are invalid, and alg.1 based on fact 4 and alg.2 based on table 1 are disordered and wrong logically. Further, manifest through a repeated experiment and ex.5 that the data at table 2 is falsified, and the example in [8] is woven elaborately. We explain why Cx = Ax * W^f(x) (% M) is changed to Cx = (Ax * W^f(x))^d (% M) in REESSE1+ v2.1. To the signature fraud, we point out that [8] misunderstands the existence of T^-1 and Q^-1 % (M-1), and forging of Q can be easily avoided through moving H. Therefore, the conclusion of [8] that REESSE1+ is not secure at all (which connotes that [8] can extract a related private key from any public key in REESSE1+) is fully incorrect, and as long as the parameter Omega is fitly selected, REESSE1+ with Cx = Ax * W^f(x) (% M) is secure. | Refuting the Pseudo Attack on the REESSE1+ Cryptosystem | 7,964 |
This paper presents an experimental study and the lessons learned from the observation of the attackers when logged on a compromised machine. The results are based on a six months period during which a controlled experiment has been run with a high interaction honeypot. We correlate our findings with those obtained with a worldwide distributed system of lowinteraction honeypots. | Lessons Learned from the deployment of a high-interaction honeypot | 7,965 |
A secure human identification protocol aims at authenticating human users to a remote server when even the users' inputs are not hidden from an adversary. Recently, the authors proposed a human identification protocol in the RSA Conference 2007, which is loosely based on the ability of humans to efficiently process an image. The advantage being that an automated adversary is not effective in attacking the protocol without human assistance. This paper extends that work by trying to solve some of the open problems. First, we analyze the complexity of defeating the proposed protocols by quantifying the workload of a human adversary. Secondly, we propose a new construction based on textual CAPTCHAs (Reverse Turing Tests) in order to make the generation of automated challenges easier. We also present a brief experiment involving real human users to find out the number of possible attributes in a given image and give some guidelines for the selection of challenge questions based on the results. Finally, we analyze the previously proposed protocol in detail for the relationship between the secrets. Our results show that we can construct human identification protocols based on image evaluation with reasonably ``quantified'' security guarantees based on our model. | Using Image Attributes for Human Identification Protocols | 7,966 |
Key-exchange protocols have been overlooked as a possible means for implementing oblivious transfer (OT). In this paper we present a protocol for mutual exchange of secrets, 1-out-of-2 OT and coin flipping similar to Diffie-Hellman protocol using the idea of obliviously exchanging encryption keys. Since, Diffie-Hellman scheme is widely used, our protocol may provide a useful alternative to the conventional methods for implementation of oblivious transfer and a useful primitive in building larger cryptographic schemes. | Oblivious Transfer based on Key Exchange | 7,967 |
Internet worms cause billions of dollars in damage yearly, affecting millions of users worldwide. For countermeasures to be deployed timeously, it is necessary to use an automated system to detect the spread of a worm. This paper discusses a method of determining the presence of a worm, based on routing information currently available from Internet routers. An autoencoder, which is a specialized type of neural network, was used to detect anomalies in normal routing behavior. The autoencoder was trained using information from a single router, and was able to detect both global instability caused by worms as well as localized routing instability. | Predicting the Presence of Internet Worms using Novelty Detection | 7,968 |
We introduce a new approach for cryptanalysis of key agreement protocols based on noncommutative groups. This approach uses functions that estimate the distance of a group element to a given subgroup. We test it against the Shpilrain-Ushakov protocol, which is based on Thompson's group F. | Cryptanalysis of group-based key agreement protocols using subgroup
distance functions | 7,969 |
Fuzzy sketches, introduced as a link between biometry and cryptography, are a way of handling biometric data matching as an error correction issue. We focus here on iris biometrics and look for the best error-correcting code in that respect. We show that two-dimensional iterative min-sum decoding leads to results near the theoretical limits. In particular, we experiment our techniques on the Iris Challenge Evaluation (ICE) database and validate our findings. | Optimal Iris Fuzzy Sketches | 7,970 |
It is well known that, in theory, the general secure multi-party computation problem is solvable using circuit evaluation protocols. However, the communication complexity of the resulting protocols depend on the size of the circuit that expresses the functionality to be computed and hence can be impractical. Hence special solutions are needed for specific problems for efficiency reasons. The point inclusion problem in computational geometry is a special multiparty computation and has got many applications. Previous protocols for the secure point inclusion problem are not adequate. In this paper we modify some known solutions to the point inclusion problem in computational geometry to the frame work of secure two-party computation. | Secure Two-party Protocols for Point Inclusion Problem | 7,971 |
When studying safety properties of (formal) protocol models, it is customary to view the scheduler as an adversary: an entity trying to falsify the safety property. We show that in the context of security protocols, and in particular of anonymizing protocols, this gives the adversary too much power; for instance, the contents of encrypted messages and internal computations by the parties should be considered invisible to the adversary. We restrict the class of schedulers to a class of admissible schedulers which better model adversarial behaviour. These admissible schedulers base their decision solely on the past behaviour of the system that is visible to the adversary. Using this, we propose a definition of anonymity: for all admissible schedulers the identity of the users and the observations of the adversary are independent stochastic variables. We also develop a proof technique for typical cases that can be used to proof anonymity: a system is anonymous if it is possible to `exchange' the behaviour of two users without the adversary `noticing'. | Probabilistic Anonymity and Admissible Schedulers | 7,972 |
We develop and analyze algorithms for dispersing a swarm of primitive robots in an unknown environment, R. The primary objective is to minimize the makespan, that is, the time to fill the entire region. An environment is composed of pixels that form a connected subset of the integer grid. There is at most one robot per pixel and robots move horizontally or vertically at unit speed. Robots enter R by means of k>=1 door pixels Robots are primitive finite automata, only having local communication, local sensors, and a constant-sized memory. We first give algorithms for the single-door case (i.e., k=1), analyzing the algorithms both theoretically and experimentally. We prove that our algorithms have optimal makespan 2A-1, where A is the area of R. We next give an algorithm for the multi-door case (k>1), based on a wall-following version of the leader-follower strategy. We prove that our strategy is O(log(k+1))-competitive, and that this bound is tight for our strategy and other related strategies. | Algorithms for Rapidly Dispersing Robot Swarms in Unknown Environments | 7,973 |
A double pendulum subject to external torques is used as a model to study the stability of a planar manipulator with two links and two rotational driven joints. The hamiltonian equations of motion and the fixed points (stationary solutions) in phase space are determined. Under suitable conditions, the presence of constant torques does not change the number of fixed points, and preserves the topology of orbits in their linear neighborhoods; two equivalent invariant manifolds are observed, each corresponding to a saddle-center fixed point. | Qualitative Study of a Robot Arm as a Hamiltonian System | 7,974 |
Deterministic replay is a method for allowing complex multitasking real-time systems to be debugged using standard interactive debuggers. Even though several replay techniques have been proposed for parallel, multi-tasking and real-time systems, the solutions have so far lingered on a prototype academic level, with very little results to show from actual state-of-the-practice commercial applications. This paper describes a major deterministic replay debugging case study performed on a full-scale industrial robot control system, as well as a minor replay instrumentation case study performed on a military aircraft radar system. In this article, we will show that replay debugging is feasible in complex multi-million lines of code software projects running on top of off-the-shelf real-time operating systems. Furthermore, we will discuss how replay debugging can be introduced in existing systems without impracticable analysis efforts. In addition, we will present benchmarking results from both studies, indicating that the instrumentation overhead is acceptable and affordable. | Replay Debugging of Complex Real-Time Systems: Experiences from Two
Industrial Case Studies | 7,975 |
Mobile robots have received a great deal of research in recent years. A significant amount of research has been published in many aspects related to mobile robots. Most of the research is devoted to design and develop some control techniques for robot motion and path planning. A large number of researchers have used kinematic models to develop motion control strategy for mobile robots. Their argument and assumption that these models are valid if the robot has low speed, low acceleration and light load. However, dynamic modelling of mobile robots is very important as they are designed to travel at higher speed and perform heavy duty work. This paper presents and discusses a new approach to develop a dynamic model and control strategy for wheeled mobile robot which I modelled as a rigid body that roles on two wheels and a castor. The motion control strategy consists of two levels. The first level is dealing with the dynamic of the system and denoted as Low level controller. The second level is developed to take care of path planning and trajectory generation. | Dynamic Modelling and Adaptive Traction Control for Mobile Robots | 7,976 |
An adaptive Monte Carlo localization algorithm based on coevolution mechanism of ecological species is proposed. Samples are clustered into species, each of which represents a hypothesis of the robots pose. Since the coevolution between the species ensures that the multiple distinct hypotheses can be tracked stably, the problem of premature convergence when using MCL in highly symmetric environments can be solved. And the sample size can be adjusted adaptively over time according to the uncertainty of the robots pose by using the population growth model. In addition, by using the crossover and mutation operators in evolutionary computation, intra-species evolution can drive the samples move towards the regions where the desired posterior density is large. So a small size of samples can represent the desired density well enough to make precise localization. The new algorithm is termed coevolution based adaptive Monte Carlo localization (CEAMCL). Experiments have been carried out to prove the efficiency of the new localization algorithm. | Coevolution Based Adaptive Monte Carlo Localization (CEAMCL) | 7,977 |
The study of the collaboration, coordination and negotiation among different agents in a multi-agent system (MAS) has always been the most challenging yet popular in the research of distributed artificial intelligence. In this paper, we will suggest for RoboCup simulation, a typical MAS, a general decision-making model, rather than define a different algorithm for each tactic (e.g. ball handling, pass, shoot and interception, etc.) in soccer games as most RoboCup simulation teams did. The general decision-making model is based on two critical factors in soccer games: the vertical distance to the goal line and the visual angle for the goalpost. We have used these two parameters to formalize the defensive and offensive decisions in RoboCup simulation and the results mentioned above had been applied in NOVAURO, original name is UJDB, a RoboCup simulation team of Jiangsu University, whose decision-making model, compared with that of Tsinghua University, the world champion team in 2001, is a universal model and easier to be implemented. | Design and Implementation of a General Decision-making Model in RoboCup
Simulation | 7,978 |
In this second of three short papers, I introduce some of the basic concepts of space robotics with an emphasis on some specific challenging areas of research that are peculiar to the application of robotics to space infrastructure development. The style of these short papers is pedagogical and the concepts in this paper are developed from fundamental manipulator robotics. This second paper considers the application of space manipulators to on-orbit servicing (OOS), an application which has considerable commercial application. I provide some background to the notion of robotic on-orbit servicing and explore how manipulator control algorithms may be modified to accommodate space manipulators which operate in the micro-gravity of space. | Space Robotics Part 2: Space-based Manipulators | 7,979 |
The single wheel, gyroscopically stabilized robot - Gyrover, is a dynamically stable but statically unstable, underactuated system. In this paper, based on the dynamic model of the robot, we investigate two classes of nonholonomic constraints associated with the system. Then, based on the backstepping technology, we propose a control law for balance control of Gyrover. Next, through transferring the systems states from Cartesian coordinate to polar coordinate, control laws for point-to-point control and line tracking in Cartesian space are provided. | Gyroscopically Stabilized Robot: Balance and Tracking | 7,980 |
The sewer inspection robot MAKRO is an autonomous multi-segment robot with worm-like shape driven by wheels. It is currently under development in the project MAKRO-PLUS. The robot has to navigate autonomously within sewer systems. Its first tasks will be to take water probes, analyze it onboard, and measure positions of manholes and pipes to detect polluted-loaded sewage and to improve current maps of sewer systems. One of the challenging problems is the controller software, which should enable the robot to navigate in the sewer system and perform the inspection tasks autonomously, not inflicting any self-damage. This paper focuses on the route planning and replanning aspect of the robot. The robots software has four different levels, of which the planning system is the highest level, and the remaining three are controller levels each with a different degree of abstraction. The planner coordinates the sequence of actions that are to be successively executed by the robot. | Dynamic replanning in uncertain environments for a sewer inspection
robot | 7,981 |
Cyberbotics Ltd. develops WebotsTM, a mobile robotics simulation software that provides you with a rapid prototyping environment for modelling, programming and simulating mobile robots. The provided robot libraries enable you to transfer your control programs to several commercially available real mobile robots. WebotsTM lets you define and modify a complete mobile robotics setup, even several different robots sharing the same environment. For each object, you can define a number of properties, such as shape, color, texture, mass, friction, etc. You can equip each robot with a large number of available sensors and actuators. You can program these robots using your favorite development environment, simulate them and optionally transfer the resulting programs onto your real robots. WebotsTM has been developed in collaboration with the Swiss Federal Institute of Technology in Lausanne, thoroughly tested, well documented and continuously maintained for over 7 years. It is now the main commercial product available from Cyberbotics Ltd. | WebotsTM: Professional Mobile Robot Simulation | 7,982 |
A rigid-flexible manipulator may be assigned tasks in a moving environment where the winds or vibrations affect the position and/or orientation of surface of operation. Consequently, losses of the contact and perhaps degradation of the performance may occur as references are changed. When the environment is moving, knowledge of the angle α between the contact surface and the horizontal is required at every instant. In this paper, different profiles for the time varying angle α are proposed to investigate the effect of this change into the contact force and the joint torques of a rigid-flexible manipulator. The coefficients of the equation of the proposed rotating surface are changing with time to determine the new X and Y coordinates of the moving surface as the surface rotates. | Dynamic simulation of task constrained of a rigid-flexible manipulator | 7,983 |
The authors propose the implementation of hybrid Fuzzy Logic-Genetic Algorithm (FL-GA) methodology to plan the automatic assembly and disassembly sequence of products. The GA-Fuzzy Logic approach is implemented onto two levels. The first level of hybridization consists of the development of a Fuzzy controller for the parameters of an assembly or disassembly planner based on GAs. This controller acts on mutation probability and crossover rate in order to adapt their values dynamically while the algorithm runs. The second level consists of the identification of theoptimal assembly or disassembly sequence by a Fuzzy function, in order to obtain a closer control of the technological knowledge of the assembly/disassembly process. Two case studies were analyzed in order to test the efficiency of the Fuzzy-GA methodologies. | Assembly and Disassembly Planning by using Fuzzy Logic & Genetic
Algorithms | 7,984 |
Traditionally, cardiac surgery has been performed through a median sternotomy, which allows the surgeon generous access to the heart and surrounding great vessels. As a paradigm shift in the size and location of incisions occurs in cardiac surgery, new methods have been developed to allow the surgeon the same amount of dexterity and accessibility to the heart in confined spaces and in a less invasive manner. Initially, long instruments without pivot points were used, however, more recent robotic telemanipulation systems have been applied that allow for improved dexterity, enabling the surgeon to perform cardiac surgery from a distance not previously possible. In this rapidly evolving field, we review the recent history and clinical results of using robotics in cardiac surgery. | Robotic Applications in Cardiac Surgery | 7,985 |
This paper introduces a six-legged autonomous robot managed by a single controller and a software core modeled on subsumption architecture. We begin by discussing the features and capabilities of IsoPod, a new processor for robotics which has enabled a streamlined implementation of our project. We argue that this processor offers a unique set of hardware and software features, making it a practical development platform for robotics in general and for subsumption-based control architectures in particular. Next, we summarize original ideas on subsumption architecture implementation for a six-legged robot, as presented by its inventor Rodney Brooks in 1980s. A comparison is then made to a more recent example of a hexapod control architecture based on subsumption. The merits of both systems are analyzed and a new subsumption architecture layout is formulated as a response. We conclude with some remarks regarding the development of this project as a hint at new potentials for intelligent robot design, opened by a recent development in embedded controller market. | One-Chip Solution to Intelligent Robot Control: Implementing Hexapod
Subsumption Architecture Using a Contemporary Microprocessor | 7,986 |
In this paper is presented an approach to achieving on-line modification of nominal biped gait without recomputing entire dynamics when steady motion is performed. Straight, dynamically balanced walk was used as a nominal gait, and applied modifications were speed-up and slow-down walk and turning left and right. It is shown that the disturbances caused by these modifications jeopardize dynamic stability, but they can be simply compensated to enable walk continuation. | How to achieve various gait patterns from single nominal | 7,987 |
We present methods that generate cooperative strategies for multi-vehicle control problems using a decomposition approach. By introducing a set of tasks to be completed by the team of vehicles and a task execution method for each vehicle, we decomposed the problem into a combinatorial component and a continuous component. The continuous component of the problem is captured by task execution, and the combinatorial component is captured by task assignment. In this paper, we present a solver for task assignment that generates near-optimal assignments quickly and can be used in real-time applications. To motivate our methods, we apply them to an adversarial game between two teams of vehicles. One team is governed by simple rules and the other by our algorithms. In our study of this game we found phase transitions, showing that the task assignment problem is most difficult to solve when the capabilities of the adversaries are comparable. Finally, we implement our algorithms in a multi-level architecture with a variable replanning rate at each level to provide feedback on a dynamically changing and uncertain environment. | A Decomposition Approach to Multi-Vehicle Cooperative Control | 7,988 |
Mixed integer linear programming (MILP) is a powerful tool for planning and control problems because of its modeling capability and the availability of good solvers. However, for large models, MILP methods suffer computationally. In this paper, we present iterative MILP algorithms that address this issue. We consider trajectory generation problems with obstacle avoidance requirements and minimum time trajectory generation problems. The algorithms use fewer binary variables than standard MILP methods and require less computational effort. | Iterative MILP Methods for Vehicle Control Problems | 7,989 |
Automobile has become the dominant transport mode in the world in the last century. In order to meet a continuously growing demand for transport, one solution is to change the control approach for vehicle to full driving automation, which removes the driver from the control loop to improve efficiency and reduce accidents. Recent work shows that there are several realistic paths towards this deployment : driving assistance on passenger cars, automated commercial vehicles on dedicated infrastructures, and new forms of urban transport (car-sharing and cybercars). Cybercars have already been put into operation in Europe, and it seems that this approach could lead the way towards full automation on most urban, and later interurban infrastructures. The European project CyberCars has brought many improvements in the technology needed to operate cybercars over the last three years. A new, larger European project is now being prepared to carry this work further in order to meet more ambitious objectives in terms of safety and efficiency. This paper will present past and present technologies and will focus on the future developments. | Cybercars : Past, Present and Future of the Technology | 7,990 |
It is very important for quadruped walking machine to keep its stability in high speed walking. It has been indicated that moment around the supporting diagonal line of quadruped in trotting gait largely influences walking stability. In this paper, moment around the supporting diagonal line of quadruped in trotting gait is modeled and its effects on body attitude are analyzed. The degree of influence varies with different initial stances of quadruped and we get the optimal initial stance of quadruped in trotting gait with maximal walking stability. Simulation results are presented. Keywords: quadruped, trotting, attitude, walking stability. | Effects of Initial Stance of Quadruped Trotting on Walking Stability | 7,991 |
The goal is the development of a simultaneous, dynamic, technological as well as logistical real-time planning and an organizational control of the production by the production units themselves, working in the production network under the use of Multi-Agent-Technology. The design of the multi-agent-based manufacturing management system, the models of the single agents, algorithms for the agent-based, decentralized dispatching of orders, strategies and data management concepts as well as their integration into the SCM, basing on the solution described, will be explained in the following. Keywords: production engineering and management, dynamic manufacturing planning and control, multi-agentsystems (MAS), supply-chain-management (SCM), e-manufacturing | An Agent-based Manufacturing Management System for Production and
Logistics within Cross-Company Regional and National Production Networks | 7,992 |
The approximate nonlinear receding-horizon control law is used to treat the trajectory tracking control problem of rigid link robot manipulators. The derived nonlinear predictive law uses a quadratic performance index of the predicted tracking error and the predicted control effort. A key feature of this control law is that, for their implementation, there is no need to perform an online optimization, and asymptotic tracking of smooth reference trajectories is guaranteed. It is shown that this controller achieves the positions tracking objectives via link position measurements. The stability convergence of the output tracking error to the origin is proved. To enhance the robustness of the closed loop system with respect to payload uncertainties and viscous friction, an integral action is introduced in the loop. A nonlinear observer is used to estimate velocity. Simulation results for a two-link rigid robot are performed to validate the performance of the proposed controller. Keywords: receding-horizon control, nonlinear observer, robot manipulators, integral action, robustness. | Nonlinear Receding-Horizon Control of Rigid Link Robot Manipulators | 7,993 |
In the past few years, the European Commission has financed several projects to examine how new technologies could improve the sustainability of European cities. These technologies concern new public transportation modes such as guided buses to form high capacity networks similar to light rail but at a lower cost and better flexibility, PRT (Personal Rapid Transit) and cybercars (small urban vehicles with fully automatic driving capabilities to be used in carsharing mode, mostly as a complement to mass transport). They also concern private vehicles with technologies which could improve the efficiency of the vehicles as well as their safety (Intelligent Speed Adaptation, Adaptive Cruise >.Control, Stop&Go, Lane Keeping,...) and how these new vehicles can complement mass transport in the form of car-sharing services. | New Technologies for Sustainable Urban Transport in Europe | 7,994 |
Path planning and obstacle avoidance are the two major issues in any navigation system. Wavefront propagation algorithm, as a good path planner, can be used to determine an optimal path. Obstacle avoidance can be achieved using possibility theory. Combining these two functions enable a robot to autonomously navigate to its destination. This paper presents the approach and results in implementing an autonomous navigation system for an indoor mobile robot. The system developed is based on a laser sensor used to retrieve data to update a two dimensional world model of therobot environment. Waypoints in the path are incorporated into the obstacle avoidance. Features such as ageing of objects and smooth motion planning are implemented to enhance efficiency and also to cater for dynamic environments. | Wavefront Propagation and Fuzzy Based Autonomous Navigation | 7,995 |
This paper presents a robust control scheme for flexible link robotic manipulators, which is based on considering the flexible mechanical structure as a system with slow (rigid) and fast (flexible) modes that can be controlled separately. The rigid dynamics is controlled by means of a robust sliding-mode approach with wellestablished stability properties while an LQR optimal design is adopted for the flexible dynamics. Experimental results show that this composite approach achieves good closed loop tracking properties both for the rigid and the flexible dynamics. | Control of a Lightweight Flexible Robotic Arm Using Sliding Modes | 7,996 |
This paper presents a new architecture called FAIS for imple- menting intelligent agents cooperating in a special Multi Agent environ- ment, namely the RoboCup Rescue Simulation System. This is a layered architecture which is customized for solving fire extinguishing problem. Structural decision making algorithms are combined with heuristic ones in this model, so it's a hybrid architecture. | A Hybrid Three Layer Architecture for Fire Agent Management in Rescue
Simulation Environment | 7,997 |
This paper investigates the problem of the dynamic balance control of multi-arm free-floating space robot during capturing an active object in close proximity. The position and orientation of space base will be affected during the operation of space manipulator because of the dynamics coupling between the manipulator and space base. This dynamics coupling is unique characteristics of space robot system. Such a disturbance will produce a serious impact between the manipulator hand and the object. To ensure reliable and precise operation, we propose to develop a space robot system consisting of two arms, with one arm (mission arm) for accomplishing the capture mission, and the other one (balance arm) compensating for the disturbance of the base. We present the coordinated control concept for balance of the attitude of the base using the balance arm. The mission arm can move along the given trajectory to approach and capture the target with no considering the disturbance from the coupling of the base. We establish a relationship between the motion of two arm that can realize the zeros reaction to the base. The simulation studies verified the validity and efficiency of the proposed control method. | Dynamic Balance Control of Multi-arm Free-Floating Space Robots | 7,998 |
A resolved acceleration control (RAC) and proportional-integral active force control (PIAFC) is proposed as an approach for the robust motion control of a mobile manipulator (MM) comprising a differentially driven wheeled mobile platform with a two-link planar arm mounted on top of the platform. The study emphasizes on the integrated kinematic and dynamic control strategy in which the RAC is used to manipulate the kinematic component while the PIAFC is implemented to compensate the dynamic effects including the bounded known/unknown disturbances and uncertainties. The effectivenss and robustness of the proposed scheme are investigated through a rigorous simulation study and later complemented with experimental results obtained through a number of experiments performed on a fully developed working prototype in a laboratory environment. A number of disturbances in the form of vibratory and impact forces are deliberately introduced into the system to evaluate the system performances. The investigation clearly demonstrates the extreme robustness feature of the proposed control scheme compared to other systems considered in the study. | Robust Motion Control for Mobile Manipulator Using Resolved Acceleration
and Proportional-Integral Active Force Control | 7,999 |
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