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750 results

    • Seminar

    • Cryptography

    Wild McEliece Incognito

    • April 01, 2011

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

    Speaker : Christiane Peters - Technische Universiteit Eindhoven

    The McEliece cryptosystem is based on classical Goppa codes over F_2. Generalizations of the McEliece cryptosystem using Goppa codes over larger fields F_q were investigated but not found to offer advantages for small q. We showed that codes over F_31 offer advantages in key size compared to codes over F_2 while maintaining the same security level against all attacks known. However, codes over[…]
    • Seminar

    • Cryptography

    Isogeny computation in small characteristic

    • April 30, 2010

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

    Speaker : Lucas De Feo - LIX

    Isogenies are an important tool in the study of elliptic curves. As such their applications in Elliptic Curve Cryptography are numerous, ranging from point counting to new cryptographic schemes.<br/> The problem of finding explicit formulae expressing an isogeny between two elliptic curves has been studied by many. Vélu gave formulae for the case where the curves are defined over C; these formulae[…]
    • Seminar

    • Cryptography

    Hachage vers les courbes elliptiques et hyperelliptiques

    • October 29, 2010

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

    Speaker : Méhdi Tibouchi - ENS

    Dans de nombreux protocoles cryptographiques, notamment à base de couplages, il est nécessaire de disposer de fonctions de hachage à valeur dans le groupe des points d'une courbe elliptique (ou plus généralement dans la jacobienne d'une courbe hyperelliptique). Nous expliquerons comment il est possible de construire de telles fonctions à partir de fonctions de hachage plus classiques (à valeur[…]
    • Seminar

    • Cryptography

    Hardware Operators for Pairing-Based Cryptography

    • March 13, 2009

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

    Speaker : 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[…]
    • Seminar

    • Cryptography

    Algebraic Analysis of MinRank

    • November 27, 2009

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

    Speaker : 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[…]
    • Seminar

    • Cryptography

    Computing isogenies of small degrees on Abelian Varieties

    • April 17, 2009

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

    Speaker : Damien Robert - LORIA

    Isogenies are an essential tool in Elliptic Curves cryptography, where they are used in a wide variety of area: fast point counting, complex multiplication methods... Velu's formulas give an efficient method for computing such isogenies, but there are no formula known for curves of higher genera or general abelian varieties (except some special case for isogenies of degree 2). In this talk we will[…]