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655 results

    • Seminar

    • Cryptography

    Bad reduction of genus 3 curves with complex multiplication

    • October 17, 2014

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

    Speaker : Garcia Lorenzo - Université de Catalogne

    Let C be a smooth, absolutely irreducible genus 3 curve over a number field M. Suppose that the Jacobian of C has complex multiplication by a sextic CM-field K. Suppose further that K contains no imaginary quadratic subfield. We give a bound on the primes P of M such that the stable reduction of C at P contains three irreducible components of genus 1.
    • Seminar

    • Cryptography

    Is there an L(1/4) algorithm for the discrete logarithm problem in algebraic curves?

    • March 27, 2015

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

    Speaker : Maike Massierer - LORIA

    The function field sieve, an algorithm of subexponential complexity L(1/3) that computes discrete logarithms in finite fields, has recently been improved to an L(1/4) algorithm, and subsequently to a quasi-polynomial time algorithm. Since index calculus algorithms for computing discrete logarithms in Jacobians of algebraic curves are based on very similar concepts and results, the natural question[…]
    • Seminar

    • Cryptography

    Keep your friends close with distance-bounding protocols

    • February 07, 2014

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

    Speaker : Maria Cristina Onete - IRISA

    Authentication protocols, run between a prover and a verifier, allow the verifier to check the legitimacy of the prover. A legitimate prover should always authenticate (the correctness requirement), while illegitimate parties (adversaries) should not authenticate (the soundness or impersonation resistance requirement). Secure authentication protocols thwart most Man-in-the-Middle (MIM) attacks,[…]
    • Seminar

    • Cryptography

    SCREAM/iSCREAM: Side-Channel Resistant Authenticated Encryption with

    • November 14, 2014

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

    Speaker : François-Xavier Standaert - Université Catholique de Louvain

    In this talk, I will describe the family of authenticated encryption (with associated data) algorithms SCREAM and iSCREAM. They are based on Liskov et al.'s Tweakable Authenticated Encryption (TAE) mode with the new tweakable block ciphers Scream and iScream. The main desirable features of SCREAM and iSCREAM are:<br/> * A simple and regular design allowing excellent performances on a wide range of[…]
    • Seminar

    • Cryptography

    Un algorithme pour trouver toutes les formules calculant une application bilinéaire.

    • April 18, 2014

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

    Speaker : Nicolas Estibal - IRISA

    La multiplication est une opération arithmétique coûteuse comparativement à l'addition. Aussi il est intéressant, étant donné une application, de minimiser le nombre de produits à effectuer pour la calculer. Dans cette étude, nous nous restreignons au cas des applications bilinéaires.<br/> En effet, parmi les applications bilinéaires, nous étions intéressés en premier lieu par la multiplication[…]
    • Seminar

    • Cryptography

    How to find low-weight polynomial multiples.

    • June 13, 2014

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

    Speaker : Carl Löndahl - Université de Lund

    We present an improved algorithm for finding low-weight multiples of polynomials over the binary field using coding heoretic methods. The associated code defined by the given olynomial has a cyclic structure, allowing an algorithm to earch for shifts of the sought minimum-weight odeword. Therefore, a code with higher dimension is onstructed, having a larger number of low-weight codewords nd[…]