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• • Séminaire

  • Cryptographie

  Breaking the F-FCSR-H stream cipher in real time

  • 16 janvier 2009

  • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

  Orateur : Thomas Johanson - Lund University

  The F-FCSR stream cipher family has been presented a few years ago. Apart from some flaws in the initial propositions, corrected in a later stage, there are no known weaknesses of the core of these algorithms. The hardware oriented version, called FCSR-H, is one of the ciphers selected for the eSTREAM portfolio. In this paper we present a new and severe cryptanalytic attack on the F-FCSR stream[…]

• • Séminaire

  • Cryptographie

  Key Recovery Attacks of Practical Complexity on AES Variants With Up To 10 Rounds

  • 25 septembre 2009

  • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

  Orateur : Orr Dunkelman - ENS

  AES is the best known and most widely used block cipher. Its three versions (AES-128, AES-192, and AES-256) differ in their key sizes (128 bits, 192 bits and 256 bits) and in their number of rounds (10, 12, and 14, respectively). In the case of AES-128, there is no known attack which is faster than the 2^{128} complexity of exhaustive search. However, AES-192 and AES-256 were recently shown to be[…]

• • Séminaire

  • Cryptographie

  Hardware Operators for Pairing-Based Cryptography

  • 13 mars 2009

  • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

  Orateur : Jean-Luc Beuchat - University of Tsukuba

  This talk is devoted to the design of fast parallel accelerators for the cryptographic Tate pairing. We propose here a novel hardware implementation of Miller's loop based on a pipelined Karatsuba-Ofman multiplier. Thanks to a careful choice of the mean of computing the Tate pairing and algorithms for tower field arithmetic, we manage to keep the pipeline busy. We also describe the strategies we[…]

• • Séminaire

  • Cryptographie

  Algebraic Analysis of MinRank

  • 27 novembre 2009

  • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

  Orateur : Françoise Levy-dit-Vehel - ENSTA

  We here investigate the hardness of one of the most relevant problems in multivariate cryptography, namely MinRank: given non-negative intgers n,k,r, and matrices M_0,...,M_k, of size n with entries in F_q, decide whether there exists an F_q-linear combination of those matrices which has rank less than or equal to r. Our starting point is the Kipnis-Shamir modeling of the problem. We first prove[…]

• • Séminaire

  • Cryptographie

  Utilisation de techniques de codage pour la cryptanalyse linéaire

  • 07 décembre 2007

  • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

  Orateur : Benoît Gérard le Bobinnec - INRIA

  Les techniques issues de la théorie des codes correcteurs d'erreurs se révèlent être très utiles dans le domaine de la cryptanalyse linéaire de systèmes de chiffrement symétriques. Ces techniques permettent en effet d'automatiser la recherche d'approximations linéaires nécessaires à ce type de cryptanalyse. De plus, la généralisation de la cryptanalyse linéaire utilisant plusieurs équations peut[…]

• • Séminaire

  • Cryptographie

  New methods for digital generation and postprocessing of true random numbers

  • 23 mai 2008

  • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

  Orateur : Jovan Golic - Telecomitalia

  Methods for true random number generation using logic gates only will be addressed. Advantages of the recently proposed Galois and Fibonacci ring oscillators will be pointed out. Methods for digital postprocessing of raw random sequences will also be discussed.