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669 results
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Seminar
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Cryptography
Discrete logarithm computation in finite fields GF(p^k) with NFS
Speaker : Aurore Guillevic - INRIA
Pairings on elliptic curves are involved in signatures, NIZK, and recently in blockchains (ZK-SNARKS).<br/> These pairings take as input two points on an elliptic curve E over a finite field, and output a value in an extension of that finite field. Usually for efficiency reasons, this extension degree is a power of 2 and 3 (such as 12,18,24), and moreover the characteristic of the finite field has[…] -
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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
Learning Strikes Again: the Case of the DRS Signature Scheme
Speaker : 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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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
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
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[…] -