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• • Séminaire

  • Cryptographie

  Soutenance de thèse: Autour de la sécurité des messageries instantanées: des solutions pour des applications multi-appareils et les communications de groupe.

  • 14 décembre 2021

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

  Orateur : Céline Duguey - DGA-Rennes

  Les applications de messagerie instantanée sécurisée, telles WhatsApp ou Signal, sont devenues incontournables pour nos communications quotidiennes.<br/> Elles apportent une sécurité caractérisée notamment par le chiffrement de bout en bout, la confidentialité persistante ou encore la sécurité après compromission. Mais ces propriétés sont généralement limitées aux communications deux à deux. L[…]

• • Séminaire

  • Cryptographie

  Computing isogenies from modular equations in genus 2

  • 10 janvier 2020

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

  Orateur : Jean Kieffer - Université Bordeaux 1

  Given two l-isogenous elliptic curves, a well-known algorithm of Elkies uses modular polynomials to compute this isogeny explicitly. In this work, we generalize his ideas to Jacobians of genus 2 curves. Our algorithms works for both l-isogenies and (in the RM case) cyclic isogenies, and uses Siegel or Hilbert type modular equations respectively. This has applications for point counting in genus 2:[…]

• • Séminaire

  • Cryptographie

  Key recovery from partial information

  • 01 octobre 2021

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

  Orateur : Gabrielle De Michelli - UC San Diego

  The security of deployed protocols not only relies on the hardness of the underlying mathematical problem but also on the implementation of the algorithms involved. Many fast modular exponentiation algorithms have piled up over the years and some implementations have brought vulnerabilities that are exploitable by side-channel attacks, in particular cache attacks.<br/> In this talk, we consider[…]

• • Séminaire

  • Cryptographie

  Constant time implementation of rank based cryptography

  • 01 avril 2022

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

  Orateur : Nicolas Aragon - IRISA

  Since the start of the NIST standardization project for post-quantum cryptography in 2017, rank metric based cryptography is becoming more popular as an alternative to code-based cryptography in the Hamming metric.<br/> While rank based cryptography has always been competitive in terms of keys and ciphertexts sizes, the lack of maturity in the implementations of these cryptosystems made them[…]

• • Séminaire

  • Cryptographie

  Improved Classical and Quantum Algorithms for Subset-Sum

  • 06 mars 2020

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

  Orateur : André Schrottenloher - INRIA

  We present new classical and quantum algorithms for solving random hard instances of the subset-sum problem, in which we are given n integers on n bits and try to find a subset of them that sums to a given target. This classical NP-complete problem has several applications in cryptography and underlies the security of some proposed post-quantum cryptosystems.<br/> At EUROCRYPT 2010, Howgrave[…]

• • Séminaire

  • Cryptographie

  Workshop mise en oeuvre de la cryptographie post-quantique

  • 17 novembre 2021

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

  Orateur : European CyberWeek - Rennes

  L'inscription est gratuite mais obligatoire, en particulier pour des raisons de jauges. Le nombre de places est limité. Le programme est disponible à l'adresse <a href="https://www.european-cyber-week.eu/cryptographie-post-quantique">https://www.european-cyber-week.eu/cryptographie-post-quantique</a><br/&gt;