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627 results
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Seminar
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Cryptography
Homomorphic Signatures on Randomizable Ciphertexts
Speaker : David Pointcheval - ENS
Anonymity is a primary ingredient for our digital life. Several tools have been designed to address it such as, for authentication, blind signatures, group signatures or anonymous credentials and, for confidentiality, randomizable encryption or mix-nets.<br/> When it comes to complex electronic voting schemes, random shuffling of ciphertexts with mix-nets is the only known tool. Such mix-nets are[…] -
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Seminar
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Cryptography
Soutenance de thèse (exceptionnellement jeudi à 14h): Couches de diffusion linéaires à partir de matrices MDS
Speaker : Victor Cauchois - DGA/Université Rennes 1
Cette thèse s’intéresse à deux aspects de la cryptologie symétrique liés à l’utilisation de matrices MDS dans les couches de diffusion linéaires de primitives. Une première partie se fonde sur les conceptions de couches de diffusion linéaires de schémas de chiffrement symétrique à partir de matrices MDS. Les associations entre matrices récursives, respectivement circulantes, et polynômes sont[…] -
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Seminar
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Cryptography
Unifying Leakage Models on a Renyi Day
Speaker : Thomas Prest - PqShield
In the last decade, several works have focused on finding the best way to model circuit leakage in order to obtain provably secure implementations. One of the most realistic models is the noisy leakage model, introduced in (Prouff, Rivain'13) and (Duc-Dziembowski-Faust'14) together with secure constructions. These works suffer from various limitations, in particular the use of ideal leak-free[…] -
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Seminar
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Cryptography
Optimisation des Principaux Composants des Chiffrements par Bloc
Speaker : Baptiste Lambin - soutenance de thèse salle Métivier à l'IRISA, 14h
La sécurité des chiffrements par bloc évolue constamment au fur et à mesure que de nouvelles techniques de cryptanalyse sont découvertes. Lors de la conception de nouveaux chiffrements par bloc, il est donc nécessaire de considérer ces nouvelles techniques dans l'analyse de sécurité. Dans cette thèse, nous montrons comment construire certaines opérations internes des chiffrements par bloc pour[…] -
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Seminar
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Cryptography
Learning With Errors and Extrapolated Dihedral Cosets Problem
Speaker : Weiqiang Wen - ENS de Lyon
The hardness of the learning with errors (LWE) problem is one of the most fruitful resources of modern cryptography. In particular, it is one of the most prominent candidates for secure post-quantum cryptography. Understanding its quantum complexity is therefore an important goal. We show that under quantum polynomial time reductions, LWE is equivalent to a relaxed version of the dihedral coset[…] -
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Seminar
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Cryptography
Number Systems and Cryptography, some examples
Speaker : Jean-Claude Bajard - Sorbonne Université
Number systems are behind a lot of implementations. The role of representation is often underrated while its importance in implementation is crucial. We survey here some classes of fundamental systems that could be used in crypotgraphy. We present three main categories:<br/> - systems based on the Chinese Remainder Theorem which enter more generally in the context of polynomial interpolation,<br/[…] -