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    • Seminar

    • Cryptography

    Biometric-based Authentication Schemes using Private Information Retrieval

    • March 16, 2007

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

    Speaker : Julien Bringer - Sagem

    This work deals with the security problems in authentication schemes employing volatile biometric features, where the authentication is indeed a comparison between a fresh feature and that enrolled during the initialization phase. We propose a security model for biometric-based authentication schemes by assuming that the biometric features to be public. Extra attentions have been paid to the[…]
    • Seminar

    • Cryptography

    Utilisation des groupes de classes en cryptographie

    • December 01, 2006

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

    Speaker : Olivier Orcière - Thales

    Suite aux travaux de Bhargava sur la généralisation de la loi de Gauss sur le groupes de classes des formes quadratiques binaires, on présentera les quatre formalismes des formes quadratiques binaires utilisés et connus jusqu'à présent:<br/> - le formalisme algébrique de Gauss<br/> - le formalisme projectif de Dirichlet<br/> - le formalisme basé sur les idéaux de Schoof<br/> - le formalisme[…]
    • Seminar

    • Cryptography

    Représentations algorithmiques d'une courbe et de sa jacobienne

    • May 11, 2007

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

    Speaker : Kamal Makdisi - American University of Beirut

    Soit X une courbe algébrique lisse et projective sur un corps k. Je présente une façon de décrire X sans équations explicites, en utilisant les valeurs en plusieurs points de sections globales de fibrés en droites sur X. Cette représentation de X conduit à des algorithmes rapides pour les diviseurs sur X et pour la jacobienne de X, ainsi qu'à des approches intéressantes pour les modèles explicites[…]
    • Seminar

    • Cryptography

    Theta identities and Thomae formulas

    • December 16, 2005

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

    Speaker : Yaacov Kopeliovich

    In this talk we apply Thomae formulas to obtain algebraic relations satisfied by Riemann surfaces that are cyclic covers of the Sphere. We focus on the genus 2 case and then give an example of a higher genus case (g=4) that was not known before. The conjectural connection of these identities as well as Thomae formulas to the moduli action of the Braid group is explained.<br/> We present a[…]
    • Seminar

    • Cryptography

    Group Signatures for Federated Systems

    • June 02, 2006

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

    Speaker : Mark Manulis - Ruhr-University of Bochum

    For many mutli-party applications group signatures are important cryptographic primitives that can be used for the purpose of anonymity and privacy. In classical group signatures members of a group are able to sign messages anonymously on behalf of the group. However, there exists a designated authority, called group manager, that initializes the scheme, adds new group members, and is able to open[…]
    • Seminar

    • Cryptography

    Efficient Multi-Party Computation with Dispute Control

    • July 01, 2005

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

    Speaker : Zuzana Beerliova - ETH Zurich

    Secure multi-party computation (MPC) allows a set of $n$ players to securely compute an agreed function of their inputs, even when up to $t$ of the players are under complete adversarial control. We consider secure MPC in the information-theoretic model with broadcast channels (PKI setup) and present an efficient protocol with optimal resilience ($t< n/2$), using a new technique technique called[…]