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685 results

    • Seminar

    • Cryptography

    CSIDH: an efficient post-quantum commutative group action

    • February 01, 2019

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

    Speaker : Chloé Martindale - Technical University of Eindhoven

    CSIDH, or `commutative supersingular isogeny Diffie-Hellman' is a new isogeny-based protocol of Castryck, Lange, Martindale, Panny, and Renes.<br/> The Diffie-Hellman style scheme resulting from the group action allows for public key validation at very little cost, runs reasonably fast in practice, and has public keys of only 64 bytes at a conjectured AES-128 security level, matching NIST’s post[…]
    • Seminar

    • Cryptography

    Isogeny-based cryptography from superspecial genus-2 curves

    • October 18, 2019

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

    Speaker : Wouter Castryck - KU Leuven

    I will report on some first attempts to do isogeny-based cryptography in genus 2. More precisely, we will use isogeny graphs of superspecial principally polarized abelian surfaces over GF(p^2) for constructing variants of Charles, Goren and Lauter's hash function and of Jao and De Feo's SIDH key exchange protocol, both of which use supersingular elliptic curves over GF(p^2). This will be largely[…]
    • Seminar

    • Cryptography

    Permutations complètes en caractéristique 2.

    • February 10, 2017

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

    Speaker : Valentin Suder - Université de Versailles Saint-Quentin

    Dans ce travail, nous nous intéressons aux permutations complètes, c’est-à-dire aux fonctions bijectives $x\mapsto f(x)$ telles que $x\mapsto f(x)+x$ soient aussi bijectives. Plus particulièrement, nous nous intéressons aux permutations complètes sur les corps finis $\mathbb{F}_{2^n}$. En caractéristique 2, la définition des permutations complètes coincide avec celle des orthomorphismes. Nous[…]
    • Seminar

    • Cryptography

    CRYSTALS: Dilithium and Kyber

    • November 10, 2017

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

    Speaker : Damien Stehlé - ENS de Lyon

    Kyber -- a Key Exchange Mechanism -- and Dilithium -- a digital signature -- are the two components of the Cryptographic Suite for Algebraic Lattices (CRYSTALS). I will present the intractable problems underlying their security, overview their design and comment their practical performance. The talk is based on the following articles:<br/> https://eprint.iacr.org/2017/633.pdf<br/&gt; https:/[…]
    • Seminar

    • Cryptography

    Open problems in isogeny-based cryptography

    • May 05, 2017

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

    Speaker : Luca De Feo - Université de Versailles Saint-Quentin

    Isogeny-based cryptography (IBC) is a very young field, only 10 years old. Protocols in this family include key-exchange, encryption, "provably secure" hash functions and trapdoor systems. Hardness assumptions in IBC come from the difficulty of finding paths in isogeny graphs, that is graphs of elliptic curves linked by isogenies of some prescribed degree.<br/> Recently some IBC protocols have[…]
    • Seminar

    • Cryptography

    Identification d'Algorithmes Cryptographiques dans du Code Natif

    • December 12, 2017

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

    Speaker : Pierre Lestringant - Soutenance de thèse à 14h en salle Métivier (IRISA)

    Durant ma thèse j’ai travaillé à la conception de méthodes automatisées permettant l’identification d’algorithmes cryptographiques dans des programmes compilés en langage machine. Ce besoin bien spécifique trouve une partie de son origine dans le domaine de l’évaluation logicielle. L’utilisation d’algorithmes cryptographiques se fait dans le but d’obtenir des fonctions de sécurité telles que la[…]