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698 résultats

• • Séminaire

  • Cryptographie

  Tightly Secure CCA-Secure Encryption without Pairings.

  • 25 novembre 2016

  • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

  Orateur : Romain Gay - ENS

  (Joint work with Dennis Hofheinz, Eike Kiltz and Hoeteck Wee) We present the first CCA-secure public-key encryption scheme based on DDH where the security loss is independent of the number of challenge ciphertexts and the number of decryption queries. Our construction extends also to the standard k-Lin assumption in pairing-free groups, whereas all prior constructions starting with Hofheinz and[…]

• • Séminaire

  • Cryptographie

  identity-based encryption with rank metric

  • 15 septembre 2017

  • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

  Orateur : Adrien Hauteville - Université de Limoges

  Code-based cryptography has a long history, almost as long as the history of public-key encryption (PKE). While we can construct almost all primitives from codes such as PKE, signature, group signature etc, it is a long standing open problem to construct an identity-based encryption from codes. We solve this problem by relying on codes with rank metric. The concept of identity-based encryption […]

• • Séminaire

  • Cryptographie

  Low-Complexity Cryptographic Hash Functions

  • 13 janvier 2017

  • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

  Orateur : Vinod Vaikuntanathan - Massachusetts Institute of Technology

  Cryptographic hash functions are efficiently computable functions that shrink a long input into a shorter output while achieving some of the useful security properties of a random function. The most common type of such hash functions is collision resistant hash functions (CRH), which prevent an efficient attacker from finding a pair of inputs on which the function has the same output.<br/> Despite[…]

• • Séminaire

  • Cryptographie

  Permutations complètes en caractéristique 2.

  • 10 février 2017

  • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

  Orateur : Valentin Suder - Université de Versailles Saint-Quentin

  Dans ce travail, nous nous intéressons aux permutations complètes, c’est-à-dire aux fonctions bijectives $x\mapsto f(x)$ telles que $x\mapsto f(x)+x$ soient aussi bijectives. Plus particulièrement, nous nous intéressons aux permutations complètes sur les corps finis $\mathbb{F}_{2^n}$. En caractéristique 2, la définition des permutations complètes coincide avec celle des orthomorphismes. Nous[…]

• • Séminaire

  • Cryptographie

  CRYSTALS: Dilithium and Kyber

  • 10 novembre 2017

  • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

  Orateur : Damien Stehlé - ENS de Lyon

  Kyber -- a Key Exchange Mechanism -- and Dilithium -- a digital signature -- are the two components of the Cryptographic Suite for Algebraic Lattices (CRYSTALS). I will present the intractable problems underlying their security, overview their design and comment their practical performance. The talk is based on the following articles:<br/> https://eprint.iacr.org/2017/633.pdf<br/&gt; https:/[…]

• • Séminaire

  • Cryptographie

  Open problems in isogeny-based cryptography

  • 05 mai 2017

  • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

  Orateur : Luca De Feo - Université de Versailles Saint-Quentin

  Isogeny-based cryptography (IBC) is a very young field, only 10 years old. Protocols in this family include key-exchange, encryption, "provably secure" hash functions and trapdoor systems. Hardness assumptions in IBC come from the difficulty of finding paths in isogeny graphs, that is graphs of elliptic curves linked by isogenies of some prescribed degree.<br/> Recently some IBC protocols have[…]