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669 results

    • Seminar

    • Cryptography

    Optimisation des Principaux Composants des Chiffrements par Bloc

    • October 22, 2019

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

    Speaker : Baptiste Lambin - soutenance de thèse salle Métivier à l'IRISA, 14h

    La sécurité des chiffrements par bloc évolue constamment au fur et à mesure que de nouvelles techniques de cryptanalyse sont découvertes. Lors de la conception de nouveaux chiffrements par bloc, il est donc nécessaire de considérer ces nouvelles techniques dans l'analyse de sécurité. Dans cette thèse, nous montrons comment construire certaines opérations internes des chiffrements par bloc pour[…]
    • Seminar

    • Cryptography

    Practical Strategy-Resistant Privacy-Preserving Elections

    • October 19, 2018

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

    Speaker : Quentin Santos - Orange

    Recent advances in cryptography promise to let us run com- plex algorithms in the encrypted domain. However, these results are still mostly theoretical since the running times are still much larger than their equivalents in the plaintext domain. In this context, Majority Judgment is a recent proposal for a new voting system with several interesting practical advantages, but which implies a more[…]
    • Seminar

    • Cryptography

    Quantum security of the Fiat-Shamir transform of commit and open protocols

    • April 26, 2019

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

    Speaker : André Chailloux - INRIA

    Applying the Fiat-Shamir transform on identification schemes is one of the main ways of constructing signature schemes. While the classical security of this transformation is well understood, there are still many cases for which we do not know whether the quantum security holds or not. In this paper, we show that if we start from a commit-and-open identification scheme, where the prover first[…]
    • Seminar

    • Cryptography

    Aggregate Cash Systems: A Cryptographic Investigation of Mimblewimble

    • November 30, 2018

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

    Speaker : Michele Orru - ENS

    • Seminar

    • Cryptography

    Cocks-Pinch curves of embedding degree five to eight and optimal ate pairing computation

    • June 21, 2019

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

    Speaker : Simon Masson - Loria, Nancy

    Recent algorithmic improvements of discrete logarithm computation in special extension fields threaten the security of pairing-friendly curves used in practice. A possible answer to this delicate situation is to propose alternative curves that are immune to these attacks, without compromising the efficiency of the pairing computation too much. We follow this direction, and focus on embedding[…]
    • Seminar

    • Cryptography

    Horizontal isogeny graphs of ordinary abelian varieties and the discrete logarithm problem

    • February 09, 2018

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

    Speaker : Benjamin WESOLOWSKI - École Polytechnique Federale de Lausanne

    An isogeny graph is a graph whose vertices are abelian varieties (typically elliptic curves, or Jacobians of genus 2 hyperelliptic curves) and whose edges are isogenies between them. Such a graph is "horizontal" if all the abelian varieties have the same endomorphism ring. We study the connectivity and the expander properties of these graphs. We use these results, together with a recent algorithm[…]