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• • Séminaire

  • Cryptographie

  On the Construction of Lightweight S-Boxes

  • 15 décembre 2017

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

  Orateur : Sébastien Duval - INRIA Paris-Rocquencourt

  S-Boxes are essential objects in the conception of blockciphers. Typically, an S-Box is simply a permutation (bijective function) on n bits, with n small (usually 4 or 8). Its role in a blockcipher is to bring nonlinearity to the cipher, thus an S-Box must be highly nonlinear. Several parameters of a function are used to measure nonlinearity, among which the most important are differential[…]

• • 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

  Certification de représentations galoisiennes modulaires

  • 11 décembre 2015

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

  Orateur : Nicolas Mascot - Université de Bordeaux 1

  Nous verrons comment certifier algorithmiquement des calculs de représentations galoisiennes associés à des formes modulaires, en nous appuyant notamment sur le théorème de Khare-Wintenberger (ex conjecture de modularité de Serre) et des calculs de cohomologie des groupes afin de déterminer le groupe de Galois de certains polynômes.

• • Séminaire

  • Cryptographie

  The Analysis of Error-Correcting Capabilities of Non-Binary LDPC Codes

  • 16 septembre 2016

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

  Orateur : Alexei Frolov - Institute for Information Transmission Problems of the Russian Academy of Sciences (IITP RAS)

  Non-binary low-density parity-check (NB LDPC) codes significantly outperform their binary counterparts. Moreover, NB LDPC codes are especially good for the channels with burst errors and high-order modulations. This talk is devoted to the analysis of error-correcting capabilities of NB LDPC codes.<br/> We start with distance properties of NB LDPC codes. We consider two approaches to obtain upper[…]