523 results
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Isogeny computation in small characteristic
Speaker : Lucas De Feo - LIX
Isogenies are an important tool in the study of elliptic curves. As such their applications in Elliptic Curve Cryptography are numerous, ranging from point counting to new cryptographic schemes.<br/> The problem of finding explicit formulae expressing an isogeny between two elliptic curves has been studied by many. Vélu gave formulae for the case where the curves are defined over C; these formulae[…] -
On the related-key attacks against AES
Speaker : Vincent Rijmen - University of Graz
In a recent series of papers, Alex Biryukov, Dmitry Khovratovich (et al.) presented a number of related-key attacks on AES and reduced-round versions of AES. The most impressive of these were presented at Asiacrypt 2009: related-key attacks against the full AES-256 and AES-192. The publication of these attacks has led some people to question the security of AES.<br/> While we agree that the[…] -
Cryptanalyse d'ESSENCE
Speaker : Yann Laigle-Chapuy - INRIA
La fonction de hachage ESSENCE faisait partie des candidats soumis au concours organisé par le NIST afin de définir de nouveaux standards. Nous présenterons dans cet exposé une attaque sur les versions complètes de ESSENCE-256 et ESSENCE-512 de complexités respectives $2^{67.4}$ et $2^{134.7}$. Ces attaques sont basées sur une cryptanalyse différentielle classique et nous détaillerons[…] -
Attaque DPA contre l'algorithme de Miller
Speaker : Nadia El-Mrabet - Université de Montpellier
Les couplages ont permis la simplification de protocoles existants et la création de protocoles originaux, par exemple la cryptographie basée sur l'identité. Durant un protocole basé sur l'identité, l'utilisateur calcule un couplage entre une entrée secrète et une entrée publique. Nous pouvons alors appliquer des attaques à canaux cachés pour tenter de retrouver ce secret. Nous nous intéressons[…] -
Computing Igusa class polynomials
Speaker : Marco Streng - Leiden University
Igusa class polynomials are the genus-2 analogue of the classical Hilbert class polynomials. We explain these notions and discuss the differences between the classical (elliptic) case and the genus-2 case, mostly from a computational perspective. One of the main applications of Igusa class polynomials is the construction of genus-2 curves that are suitable for cryptography. -
Humbert Surfaces and Isogeny Relations
Speaker : David Gruenewald - Institut Mathématiques de Luminy
In this talk, we present methods for computing Humbert surface equations and isogeny relations using Fourier expansions of Siegel modular forms. Both provide improvements to the running time of the CRT algorithm for computing Igusa class polynomials, which we illuminate with an example.