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732 results

    • Seminar

    • Cryptography

    The probability that a F_q-hypersurface is smooth

    • June 27, 2008

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

    Speaker : Jeroen Demeyer - Universiteit Gent

    Consider the projective space P^n over a finite field F_q. A hypersurface is defined by one homogenous equation with coefficients in F_q. For d going to infinity, we show that the probability that a hypersurface of degree d is nonsingular approaches 1/\zeta_{P^n (n+1)}. This is analogous to the well-known fact that the probability that an integer is squarefree equals 1/\zeta(2) = 6/\pi^2. This[…]
    • Seminar

    • Cryptography

    Generation of Prime Numbers on Portable Devices

    • November 10, 2006

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

    Speaker : Marc Joye - Thomson R&D France

    The generation of prime numbers underlies the use of most public-key cryptosystems, essentially as a primitive needed for the creation of RSA key pairs. Surprisingly enough, despite decades of intense mathematical studies on primality testing and an observed progressive intensification of cryptography, prime number generation algorithms remain scarcely investigated and most real-life[…]
    • Seminar

    • Cryptography

    Vérification formelle de compilateurs

    • March 30, 2007

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

    Speaker : Xavier Leroy - INRIA Rocquencourt

    Tous les programmeurs s'attendent à ce que les compilateurs et autres outils de génération de code produisent du code exécutable qui se comporte exactement comme prescrit par le programme source. Ce n'est malheureusement pas toujours le cas : des bugs dans le compilateur peuvent conduire à la production de code machine incorrect à partir d'un source correct. Ce cas de figure est particulièrement[…]
    • Seminar

    • Cryptography

    Identification de diffusion illicite : le fingerprinting et les codes centrés

    • December 22, 2006

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

    Speaker : Fabien Galand - IRISA

    Dans le contexte de la distribution de contenu numérique, il est souvent souhaitable de pouvoir tracer l'origine des copies. Par exemple, lors de la vente de vidéos, l'acheteur n'est pas autorisé à redistribuer ce qu'il vient d'acheter. Lorsqu'il le fait, on souhaite pouvoir, à partir d'une des copies diffusées, l'identifier comme étant à l'origine de cette distribution illicite. Pour résoudre ce[…]
    • Seminar

    • Cryptography

    An l-adic CM construction for genus 2

    • June 01, 2007

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

    Speaker : David Kohel - University of Sydney

    We recall recent work on CM constructions using canonical lifts of the Frobenius isogeny: for p = 2 with Gaudry, Houtmann, Ritzenthaler, and Weng, and generalisation to p = 3 with Carls and Lubicz. I will explain how to extend this to (l,l)-isogenies for l = 2, 3 coprime to the characteristic.
    • Seminar

    • Cryptography

    Point counting in families of hyperelliptic curves

    • June 23, 2006

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

    Speaker : Hendrik Hubrechts - Leuven University

    Let p be a small prime number, F a field of characteristic p and extension degree n, and E a hyperelliptic curve over F. In cryptography one tries to exploit the hardness of determining a discrete logarithm on the jacobian of such curves. In order to achieve this it is important to know what the size of this jacobian is. This parameter can be deduced from the zeta function of the curve.<br/> We[…]