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633 results

    • Seminar

    • Cryptography

    Calcul de bases de Gröbner d'idéaux invariants sous l'action

    • September 20, 2013

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

    Speaker : Jules Svartz - LIP6

    La résolution de systèmes polynomiaux présentant des symétries est un problème naturel qui apparaît dans plusieurs contextes applicatifs (cryptographie, robotique, biologie, physique, codes correcteurs d'erreurs...) Les algorithmes usuels de calcul de bases de Gröbner détruisent en général ces symétries. Lorsque toutes les équations du système polynomial sont individuellement invariantes sous[…]
    • Seminar

    • Cryptography

    L1 a new quasi-linear LLL algorithm

    • May 13, 2011

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

    Speaker : Andy Novocin - ENS Lyon

    The LLL lattice reduction algorithm of 1982 has proven to be useful in a wide variety of fields. It can be used to approximately solve computationally difficult lattice-based problems, such as the shortest vector problem, in polynomial time. We present a new algorithm for lattice reduction which is the first algorithm to have a complexity bound which is both polynomial and quasi-linear bound in[…]
    • Seminar

    • Cryptography

    Sélection polynomiale pour NFS

    • February 15, 2013

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

    Speaker : Paul Zimmermann - LORIA

    Le problème de la sélection polynomiale pour le crible algébrique consiste à trouver deux polynômes irréductibles f(x) et g(x) à coefficients entiers ayant une racine commune modulo le nombre N à factoriser. On décrira en détail l'algorithme proposé par Kleinjung en 2008, son implantation dans CADO-NFS, et on donnera des exemples de polynômes obtenus avec cet algorithme (RSA704, B200, RSA896)[…]
    • Seminar

    • Cryptography

    Cracking Passwords with Time-memory Trade-offs

    • November 29, 2013

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

    Speaker : Gildas Avoine - IRISA

    Cryptanalytic time-memory trade-offs were introduced by Hellman in 1980 in order to perform key-recovery attacks on cryptosystems. A major advance was presented at Crypto 2003 by Oechslin, with the rainbow tables that outperform Hellman's seminal work. After introducing the cryptanalytic time-memory trade-offs, we will present in this talk a new variant of tables, known as fingerprint tables,[…]
    • Seminar

    • Cryptography

    Towards Automatic Verification of Security Proofs for

    • July 01, 2011

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

    Speaker : Marion Daubrignard - Verimag

    Providing security proofs instead of arguing lack of existing relevant attacks is a quite new approach when it comes to cryptography. In the last thirty years, a lot of work has been done to formalize security of systems and prove of the achievement of security criteria. It has resulted in the design of a great number of proofs under various hypotheses. Though a step in the right direction, these[…]
    • Seminar

    • Cryptography

    New LFSRs and FCSRs representations for stream ciphers hardware

    • April 19, 2013

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

    Speaker : Marine Minier - Université de Lyon

    In this talk, we will sum up our recent research results concerning the introduction of a new representation for FCSRs and for LFSRs. This matrix based representation allows to construct LFSRs and FCSRs with a more compact hardware representation and a quicker diffusion while preserving the usual and proven good properties (good periods, $\ell$-sequences, good statistical behaviors, etc.).[…]