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713 results
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Seminar
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Cryptography
Learning with Errors in the Exponent
Speaker : özgür Dagdelen - Darmstadt University
We initiate the study of a novel class of group-theoretic intractability problems. Inspired by the theory of learning in presence of errors [Regev, STOC'05] we ask if noise in the exponent amplifies intractability. We put forth the notion of Learning with Errors in the Exponent (LWEE) and rather surprisingly show that various attractive properties known to ex- clusively hold for lattices carry[…] -
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Seminar
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Cryptography
Chiffrement (complètement) homomorphe : de la théorie à la pratique
Speaker : Tancrède Lepoint - CryptoExperts
Le chiffrement complètement homomorphe (parfois considéré comme le Saint Graal de la cryptographie) permet d'effectuer (de façon publique) des calculs arbitraires sur des messages chiffrés. Les premières instanciations de cette surprenante primitive ne peuvent être considérées comme pratiques, chaque multiplication de deux bits chiffrés nécessitant d'être suivie par une procédure de plusieurs[…] -
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Seminar
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Cryptography
Géométries affines finies et recherche de racines dans GF(q^n)
Speaker : Luca De Féo - UVSQ
La recherche de racines dans un corps fini est un problème classique, avec de nombreuses applications en cryptographie et codage. Étant donné un polynôme de degré d à coefficients dans un corps fini GF(q^n), on cherche ses zéros dans GF(q^n).<br/> Cet exposé s'intéresse au cas où q est un petit nombre, et donc notamment au cas de la petite caractéristique. Nous présentons trois algorithmes pour la[…] -
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Seminar
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Cryptography
Beyond the black and grey box
Speaker : Yoni De Mulder - University of Leuven
In the white-box attack context, i.e., the setting where an implementation of a cryptographic algorithm is executed on an untrusted open platform, the adversary has full access to the implementation and its execution environment. As a result, the adversary is much more powerful than in a traditional black-box environment in which the adversary has only access to the inputs and outputs of a[…] -
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Seminar
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Cryptography
Bad reduction of genus 3 curves with complex multiplication
Speaker : Garcia Lorenzo - Université de Catalogne
Let C be a smooth, absolutely irreducible genus 3 curve over a number field M. Suppose that the Jacobian of C has complex multiplication by a sextic CM-field K. Suppose further that K contains no imaginary quadratic subfield. We give a bound on the primes P of M such that the stable reduction of C at P contains three irreducible components of genus 1. -
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Seminar
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Cryptography
Is there an L(1/4) algorithm for the discrete logarithm problem in algebraic curves?
Speaker : Maike Massierer - LORIA
The function field sieve, an algorithm of subexponential complexity L(1/3) that computes discrete logarithms in finite fields, has recently been improved to an L(1/4) algorithm, and subsequently to a quasi-polynomial time algorithm. Since index calculus algorithms for computing discrete logarithms in Jacobians of algebraic curves are based on very similar concepts and results, the natural question[…] -