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633 results
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Seminar
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Cryptography
Un algorithme de comptage de points pour les recouvrements cycliques de la droite projective
Speaker : Cécile Goncalves - LIX
Nous présentons un algorithme à la Kedlaya pour compter les points de recouvrements cycliques $y^r = f(x)$ défini sur un corps fini de caractéristique $p$ ne divisant pas $r$, et avec $r$ et le degré de $f$ non nécessairement premiers entre eux.<br/> Cet algorithme généralise l'algorithme de Gaudry et Gürel pour les courbes superelliptiques à une classe de courbe plus générale, avec[…] -
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Seminar
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Cryptography
Analysis of BKZ
Speaker : Xavier Pujol - ENS Lyon
Strong lattice reduction is the key element for most attacks against lattice-based cryptosystems. Between the strongest but impractical HKZ reduction and the weak but fast LLL reduction, there have been several attempts to find efficient trade-offs. Among them, the BKZ algorithm introduced by Schnorr and Euchner in 1991 seems to achieve the best time/quality compromise in practice. However, no[…] -
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Seminar
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Cryptography
Borne inférieure pour les signatures préservant la structure symétriques
Speaker : Mehdi Tibouchi - LORIA
Un schéma de signatures « préservant la structure » (SPS) est un schéma de signature numérique à clef publique dans lequel la clef publique, les messages et les signatures sont tous des n-uplets d'éléments de groupe bilinéaire, et la vérification de signature s'obtient en évaluant des produits de couplages. Cette primitive a de nombreuses applications à la construction de protocoles[…] -
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Seminar
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Cryptography
An explicit description of (log) de Rham cohomology over the Witt vector
Speaker : Moritz Minzlaff - Technische Universität Berlin
Motivated by applications to computing zeta functions, we will discuss the log de Rham and de Rham cohomologies of smooth schemes (together with 'nice' divisors) over the Witt vectors. For the former, we will give an explicit description that eventually might lead to improvements to point counting algorithms. Regarding the latter, we will measure "how far" the de Rham cohomology of a curve is from[…] -
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Seminar
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Cryptography
Keccak
Speaker : Joan Daemen - ST Micro
In October 2012, the American National Institute of Standards and Technology (NIST) announced the selection of Keccak as the winner of the SHA-3 Cryptographic Hash Algorithm Competition. This concluded an open competition that was remarkable both for its magnitude and the involvement of the cryptographic community. Public review is of paramount importance to increase the confidence in the new[…] -
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Seminar
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Cryptography
Usage of Modular Techniques for Efficient Computation of Ideal
Speaker : Kazuhiro Yokoyama - Rikkyo University
Modular techniques are widely applied to various algebraic computations. (See [1] for basic modular techniques applied to polynomial computations.) In this talk, we discuss how modular techniques are efficiently applied to computation of various ideal operations such as Gröbner base computation and ideal decompositions. Here, by *modular techniques* we mean techniques using certain projections for[…] -