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IEEE International Conference on Multimedia and Expo (ICME)

作者： A. Aner-Wolf Department of Computer Science and Applied Math Weizmann Institute of Science Rehovot Israel

A new approach for bridging over the semantic gap is presented. This approach is based solely on the extraction of low-level illumination features, and by using well defined film rules regarding scene lighting, it generates high level semantic descriptors for scenes. These illumination descriptors could be further combined with other descriptors like motion and shot tempo, to generate a more complete automatic semantic analysis of video media.

关键词： Atmosphere Layout Lighting Motion analysis Mood computer science Rhythm Atmospheric modeling Art Eyes

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On the (In)security of the Fiat-Shamir paradigm

On the (In)security of the Fiat-Shamir paradigm

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Annual IEEE Symposium on Foundations of computer science

作者： S. Goldwasser Y.T. Kalai Department of Computer Science and Electrical Engineering Massachusetts Institute of Technology USA Department of Computer Science and Applied Math Weizmann Institute of Science Rehovot Israel

In 1986, Fiat and Shamir proposed a general method for transforming secure 3-round public-coin identification schemes into digital signature schemes. The idea of the transformation was to replace the random message of the verifier in the identification scheme, with the value of some deterministic hash function evaluated on various quantities in the protocol and on the message to be signed. The Fiat-Shamir methodology for producing digital signature schemes quickly gained popularity as it yields efficient and easy to implement digital signature schemes. The most important question however remained open: are the digital signatures produced by the Fiat-Shamir methodology secure? We answer this question negatively. We show that there exist secure 3-round public-coin identification schemes for which the Fiat-Shamir transformation yields insecure digital signature schemes for any hash function used by the transformation. This is in contrast to the work of Pointcheval and Stern which proved that the Fiat-Shamir methodology always produces digital signatures secure against chosen message attack in the "Random Oracle Model" - when the hash function is modeled by a random oracle. Among other things, we make new usage of Barak's technique for taking advantage of nonblack-box access to a program, this time in the context of digital signatures.

关键词： Digital signatures Protocols computer science Law Legal factors Cryptography Design methodology computer security Forgery Cost function

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Direct methods for matrix Sylvester and Lyapunov equations

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Journal of applied mathematics 2003年第6期2003卷 277-303页

作者： Sorensen, Danny C. Zhou, Yunkai Department of Computational and Applied Mathematics Rice University Houston TX 77005-1892 United States Department of Computational and Applied Mathematics Rice University Houston TX 77005-1892 United States Argonne National Laboratory Math and Computer Science Division Argonne IL 60439 United States

We revisit the two standard dense methods for matrix Sylvester and Lyapunov equations: The Bartels-Stewart method for A1X+XA2+D=0 and Hammarling's method for AX+XAT+BBT=0 with A stable. We construct three schemes for solving the unitarily reduced quasitriangular systems. We also construct a new rank-1 updating scheme in Hammarling's method. This new scheme is able to accommodate a B with more columns than rows as well as the usual case of a B with more rows than columns, while Hammarling's original scheme needs to separate these two cases. We compared all of our schemes with the Matlab Sylvester and Lyapunov solver lyap.m;the results show that our schemes are much more efficient. We also compare our schemes with the Lyapunov solver sllyap in the currently possibly the most efficient control library package SLICOT;numerical results show our scheme to be competitive. © 2003 Hindawi Publishing Corporation. All rights reserved.

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A novel robust adaptive fuzzy controller

A novel robust adaptive fuzzy controller

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Proceedings of the 4th World Congress on Intelligent Control and Automation

作者： Liu, Xiaohua Wang, Xiuhong Fen, Enmin Dept. of Math. and Computer Science Yantai Normal University Yantai 264025 China Department of Applied Mathematics Dalian University of Technology Dalian 112064 China

ISBN: (纸本)0780372689

For a class of continuous - time nonlinear system, a novel robust adaptive fuzzy controller is proposed by using of Lyapunov method. It is proven that the control algorithm is globally stable, the output tracking - error of the system can convergence to a domain of zero under the assumptions. As a result, the system controled has stronger robustness for disturbance and modeling error.

关键词： Fuzzy control

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Arbitrary source models and Bayesian codebooks in rate-distortion theory

Arbitrary source models and Bayesian codebooks in rate-disto...

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IEEE International Symposium on Information Theory

作者： L. Kontoyiannis Junshan Zhang Division of Applied Math & Department of Computer Science Brown University USA Department of Electrical Engineering Arizona State University USA

We give a development of universal lossy data compression based on a lossy version of the Kraft inequality. As an application, we evaluate the performance of universal mixture codebooks.

关键词： Bayesian methods Rate-distortion Distortion measurement Decoding World Wide Web Loss measurement computer science Data compression Application software Probability distribution

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Asynchronous resource discovery in peer to peer networks

Asynchronous resource discovery in peer to peer networks

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Reliable Distributed Systems

作者： S. Kutten D. Peleg Faculty of Industrial Engineering & Management Technion-Israel Institute of Technology Haifa Israel Department of Computer Science and Applied Math Weizmann Institute of Science Rehovot Israel

The resource discovery problem arises in the context of peer to peer (P2P) networks, where at any point of time a peer may be placed at or removed from any location over a general purpose network (e.g., an Internet site). A vertex (peer) can communicate with another vertex directly if and only if it knows a certain routing information to that other vertex. Hence, it is critical for peers to convey this routing information to each other. The problem was formalized by Harchol-Balter et al. (1999). The routing information needed for a vertex to reach another peer is that peer's identifier (e.g., IP address). A logical directed edge represents the fact that the peer at the tail of the edge knows the IP address of the one at its head. A number of algorithms were developed by Harchol-Balter et al. for this problem in the model of a synchronous network over a weakly connected directed graph. The best of these algorithms was randomized. Subsequently, a deterministic algorithm for the problem on synchronous networks with improved complexity was presented by Kutten et al. (2001). The current paper extends this deterministic algorithm to the environment of asynchronous networks, maintaining similar complexities (translated to the asynchronous model). These are lower than the complexities that would be needed to synchronize the system. The main technical difficulty in a directed, weakly connected system is to ensure that vertices take consistent steps, even if their knowledge about each other is not symmetric, and even if there is no timeout mechanism (which does exist in synchronous systems) to assist in that.

关键词： Intelligent networks Routing Web server IP networks Context Tail Peer to peer computing Internet computer industry computer network management

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Parallel coin-tossing and constant-round secure two-party computation

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21st Annual International Cryptology Conference, CRYPTO 2001

作者： Lindell, Yehuda Department of Computer Science and Applied Math Weizmann Institute of Science Rehovot Israel

ISBN: (纸本)3540424563

In this paper we show that any two-party functionality canbe securely computed in a constant number of rounds, where security isobtained against malicious adversaries that may arbitrarily deviate fromthe protocol specification. This is in contrast to Yao's constant-roundprotocol that ensures security only in the face of semi-honest adversaries,and to its malicious adversary version that requires a polynomial numberof *** order to obtain our result, we present a constant-round protocol forsecure coin-tossing of polynomially many coins (in parallel). We thenshow how this protocol can be used in conjunction with other existingconstructions in order to obtain a constant-round protocol for securelycomputing any two-party functionality. On the subject of coin-tossing,we also present a constant-round perfect coin-tossing protocol, where by"perfect" we mean that the resulting coins are guaranteed to be statis-tically close to uniform (and not just pseudorandom). © Springer-Verlag Berlin Heidelberg 2001.

关键词： Artificial intelligence

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Session-key generation using human passwords only

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21st Annual International Cryptology Conference, CRYPTO 2001

作者： Goldreich, Oded Lindell, Yehuda Department of Computer Science and Applied Math Weizmann Institute of Science Rehovot Israel

ISBN: (纸本)3540424563

We present session-key generation protocols in a model where the legitimate parties share only a human-memorizable password. The security guarantee holds with respect to probabilistic polynomial-time adversaries that control the communication channel (between the parties), and may omit, insert and modify messages at their choice. Loosely speaking, the effect of such an adversary that attacks an execution of our protocol is comparable to an attack in which an adversary is only allowed to make a constant number of queries of the form "is w the password of Party A". We stress that the result holds also in case the passwords are selected at random from a small dictionary so that it is feasible (for the adversary) to scan the entire directory. We note that prior to our result, it was not clear whether or not such protocols were attainable without the use of random oracles or additional setup assumptions. © Springer-Verlag Berlin Heidelberg 2001.

关键词： Polynomial approximation

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A chat room assignment for teaching network security

A chat room assignment for teaching network security

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32nd SIGCSE Technical Symposium on computer science Education

作者： Mitchener, W. Garrett Vahdat, Amin Applied and Computational Math Princeton University Princeton NJ United States Department of Computer Science Duke University Durham NC United States

This paper describes a chat room application suitable for teaching basic network programming and security protocols. A client/server design illustrates the structure of current scalable network services while a multicast version demonstrates the need for efficient simultaneous distribution of network content to multiple receivers (e.g., as required by video broadcasts). The system also includes implementations of two security protocols, one similar to Kerberos and another based on public key encryption.

关键词： Engineering education

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Revocation and tracing schemes for stateless receivers?

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21st Annual International Cryptology Conference, CRYPTO 2001

作者： Naor, Dalit Naor, Moni Lotspiech, Jeff IBM Almaden Research Center 650 Harry Road San-JoseCA95120 United States Department of Computer Science and Applied Math Weizmann Institute Rehovot Israel

ISBN: (纸本)3540424563

We deal with the problem of a center sending a messageto a group of users such that some subset of the users is consideredrevoked and should not be able to obtain the content of the *** concentrate on the stateless receiver case, where the users do not(necessarily) update their state from session to session. We present aframework called the Subset-Cover framework, which abstracts a varietyof revocation schemes including some previously known ones. We pro-vide suficient conditions that guarantees the security of a revocationalgorithm in this *** describe two explicit Subset-Cover revocation algorithms;these algo-rithms are very flexible and work for any number of revoked users. Theschemes require storage at the receiver of logN and 12log2 N keys respec-tively (N is the total number of users), and in order to revoke r users therequired message lengths are of r logN and 2r keys respectively. We alsoprovide a general traitor tracing mechanism that can be integrated withany Subset-Cover revocation scheme that satisés a "bifurcation prop-erty". This mechanism does not need an a priori bound on the numberof traitors and does not expand the message length by much comparedto the revocation of the same set of *** main improvements of these methods over previously suggestedmethods, when adopted to the stateless scenario, are: (1) reducingthe message length to O(r) regardless of the coalition size whilemaintaining a single decryption at the user's end (2) provide aseamless integration between the revocation and tracing so that the trac-ing mechanisms does not require any change to the revocation algorithm. © Springer-Verlag Berlin Heidelberg 2001.

关键词： Signal receivers

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