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619 results

    • 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[…]
    • Seminar

    • Cryptography

    New candidate PRFs and their applications

    • April 12, 2019

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

    Speaker : Alain Passelègue - Inria

    In this talk, I will present new and simple candidate PRFs introduced in a recent work. In this work, we depart from the traditional approaches for building PRFs used in provable security or in applied cryptography by exploring a new space of plausible PRF candidates. Our guiding principle is to maximize simplicity while optimizing complexity measures that are relevant to advanced cryptographic[…]
    • Seminar

    • Cryptography

    Tunnels sécurisés pour environnements contraints

    • November 18, 2019

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

    Speaker : Loic Ferreira - soutenance de thèse salle Métivier à l'IRISA, 14h30

    Avec l’extension de l’Internet des Objets et l’usage croissant de terminaux à bas coût, de nombreux protocoles de sécurité sont déployés à grande échelle. Cette thèse étudie le champ des protocoles d’échange de clé authentifié basés sur des fonctions cryptographiques symétriques. Nous montrons que les protocoles existants n’atteignent pas un niveau de sécurité correspondant à l’état de l’art en[…]
    • Seminar

    • Cryptography

    Zero-Knowledge Argument for Matrix-Vector Relations and Lattice-Based Group Encryption

    • September 28, 2018

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

    Speaker : Fabrice Mouhartem - ENS Lyon

    Group encryption (GE) is the natural encryption analogue of group signatures in that it allows verifiably encrypting messages for some anonymous member of a group while providing evidence that the receiver is a properly certified group member. Should the need arise, an opening authority is capable of identifying the receiver of any ciphertext. As intro- duced by Kiayias, Tsiounis and Yung […]
    • Seminar

    • Cryptography

    Improved Veron Identification and Signature Schemes in the Rank Metric

    • June 07, 2019

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

    Speaker : Florian Caullery - Darkmatter

    Abstract—It is notably challenging to design an efficient and secure signature scheme based on error-correcting codes. An approach to build such signature schemes is to derive it from an identification protocol through the Fiat-Shamir transform.<br/> All such protocols based on codes must be run several rounds, since each run of the protocol allows a cheating probability of either 2/3 or 1/2. The[…]
    • Seminar

    • Cryptography

    Repairing the Faure-Loidreau Public-Key Cryptosystem

    • November 23, 2018

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

    Speaker : julian renns - Teschnische Universität Munchen

    A repair of the Faure–Loidreau (FL) public-key code-based cryptosystem is proposed. The FL cryptosystem is based on the hardness of list decoding Gabidulin codes which are special rank-metric codes. We prove that the recent structural attack on the system by Gaborit et al. is equivalent to decoding an interleaved Gabidulin code. Since all known polynomial-time decoders for these codes fail for a[…]