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634 résultats
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Séminaire
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Cryptographie
Implicit proofs of membership
Orateur : Olivier Blazy - Université Limoges
Smooth hash proof systems have been introduced by Cramer and shoup to build compact efficient cca2 encryption in the standard model. Since then, they found applications in a broad range of protocols from oblivious transfer to authenticated key exchange, passing by witness examples.<br/> In this talk, we will start by a panorama of languages that can be managed by such a primitive and then show how[…] -
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Séminaire
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Cryptographie
A Concrete Treatment of Efficient Continuous Group Key Agreement via Multi-Recipient PKEs
Orateur : Thomas Prest - PQShield
Continuous group key agreements (CGKAs) are a class of protocols that can provide strong security guarantees to secure group messaging protocols such as Signal and MLS. Protection against device compromise is provided by commit messages: at a regular rate, each group member may refresh their key material by uploading a commit message, which is then downloaded and processed by all the other members[…] -
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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
Learning Strikes Again: the Case of the DRS Signature Scheme
Orateur : Yu Yang - CWI Amsterdam
Lattice signature schemes generally require particular care when it comes to preventing secret information from leaking through signature transcript. For example, the Goldreich-Goldwasser-Halevi (GGH) signature scheme and the NTRUSign scheme were completely broken by the parallelepiped-learning attack of Nguyen and Regev (Eurocrypt 2006). Several heuristic countermeasures were also shown[…] -
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Séminaire
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Cryptographie
Homomorphic Signatures on Randomizable Ciphertexts
Orateur : 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[…] -