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655 results

    • Seminar

    • Cryptography

    Analysis of BKZ

    • May 27, 2011

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

    Speaker : Xavier Pujol - ENS Lyon

    Strong lattice reduction is the key element for most attacks against lattice-based cryptosystems. Between the strongest but impractical HKZ reduction and the weak but fast LLL reduction, there have been several attempts to find efficient trade-offs. Among them, the BKZ algorithm introduced by Schnorr and Euchner in 1991 seems to achieve the best time/quality compromise in practice. However, no[…]
    • Seminar

    • Cryptography

    Borne inférieure pour les signatures préservant la structure symétriques

    • March 15, 2013

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

    Speaker : Mehdi Tibouchi - LORIA

    Un schéma de signatures « préservant la structure » (SPS) est un schéma de signature numérique à clef publique dans lequel la clef publique, les messages et les signatures sont tous des n-uplets d'éléments de groupe bilinéaire, et la vérification de signature s'obtient en évaluant des produits de couplages. Cette primitive a de nombreuses applications à la construction de protocoles[…]
    • Seminar

    • Cryptography

    An explicit description of (log) de Rham cohomology over the Witt vector

    • October 19, 2012

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

    Speaker : Moritz Minzlaff - Technische Universität Berlin

    Motivated by applications to computing zeta functions, we will discuss the log de Rham and de Rham cohomologies of smooth schemes (together with 'nice' divisors) over the Witt vectors. For the former, we will give an explicit description that eventually might lead to improvements to point counting algorithms. Regarding the latter, we will measure "how far" the de Rham cohomology of a curve is from[…]
    • Seminar

    • Cryptography

    Usage of Modular Techniques for Efficient Computation of Ideal

    • December 07, 2012

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

    Speaker : Kazuhiro Yokoyama - Rikkyo University

    Modular techniques are widely applied to various algebraic computations. (See [1] for basic modular techniques applied to polynomial computations.) In this talk, we discuss how modular techniques are efficiently applied to computation of various ideal operations such as Gröbner base computation and ideal decompositions. Here, by *modular techniques* we mean techniques using certain projections for[…]
    • Seminar

    • Cryptography

    Attaques par rencontre au milieu sur l'AES.

    • October 04, 2013

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

    Speaker : Patrick Derbez - ENS

    Dans cette présentation je décrirai deux types d'attaques par rencontre au milieu sur l'AES et ses dérivés. Le premier type est en réalité une méthode générique pour résoudre des systèmes d'équations reposant sur deux techniques algorithmiques: "la rencontre par le milieu" et "diviser pour régner". Cette méthode a été pensée pour attaquer l'AES lorsque le nombre de paires clair/chiffré disponibles[…]
    • Seminar

    • Cryptography

    On the related-key attacks against AES

    • April 09, 2010

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

    Speaker : Vincent Rijmen - University of Graz

    In a recent series of papers, Alex Biryukov, Dmitry Khovratovich (et al.) presented a number of related-key attacks on AES and reduced-round versions of AES. The most impressive of these were presented at Asiacrypt 2009: related-key attacks against the full AES-256 and AES-192. The publication of these attacks has led some people to question the security of AES.<br/> While we agree that the[…]