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679 résultats
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Séminaire
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Cryptographie
PMNS for efficient arithmetic and small memory cost
Orateur : Fangan Yssouf Dosso - Ecole des Mines de Saint-Etienne
The Polynomial Modular Number System (PMNS) is an integer number system which aims to speed up arithmetic operations modulo a prime p. Such a system is defined by a tuple (p, n, g, r, E), where p, n, g and r are positive integers, E is a monic polynomial with integer coefficients, having g as a root modulo p. Most of the work done on PMNS focus on polynomials E such that E(X) = X^n – l, where l is[…] -
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Séminaire
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Cryptographie
On Rejection Sampling in Lyubashevsky's Signature Scheme
Orateur : Julien Devevey - ENS de Lyon
Lyubashevsky’s signatures are based on the Fiat-Shamir with aborts paradigm, whose central ingredient is the use of rejection sampling to transform (secret-key-dependent) signature samples into samples from a secret-key-independent distribution. The choice of these two underly- ing distributions is part of the rejection sampling strategy, and various instantiations have been considered up to this[…] -
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Séminaire
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Cryptographie
Syndrome Decoding in the Head – Shorter Signatures from Zero-Knowledge proofs
Orateur : Thibauld Feneuil - CryptoExperts et Sorbonne Université
In this talk, I will present a new zero-knowledge proof of knowledge for the syndrome decoding (SD) problem on random linear codes. Instead of using permutations like most of the existing protocols, we rely on the MPC-in-the-head paradigm in which we reduce the task of proving the low Hamming weight of the SD solution to proving some relations between specific polynomials. Specifically, we propose[…] -
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Séminaire
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Cryptographie
Middle-Product Learning with Rounding Problem and its Applications
Orateur : Katharina Boudgoust - Univ Rennes, CNRS, IRISA
This talk focuses on a new variant of the Learning With Errors (LWE) problem, a fundamental computational problem used in lattice-based cryptography.<br/> At Crypto17, Roşca et al. introduced the Middle-Product LWE problem (MP-LWE), whose hardness is based on the hardness of the Polynomial LWE (P-LWE) problem parameterized by a large set of polynomials, making it more secure against the possible[…] -
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Séminaire
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Cryptographie
Soutenance de thèse: Conception de courbes elliptiques et applications
Orateur : Rémi Clarisse - Rennes
Le thème de la sécurité de l’information est prédominant dans nos vies actuelles. En particulier, les utilisateurs de service, plus précisément en ligne, s’attendent de plus en plus à ce que leurs données à caractère personnel soient traitées dignement et avec leur consentement. Cela incite donc à concevoir des systèmes se pliant à de telles exigences. Le recours à la cryptographie permet de[…] -
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Séminaire
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Cryptographie
Computing isogenies from modular equations in genus 2
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:[…] -