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644 results

    • Seminar

    • Cryptography

    Power decoding of Hermitian codes in sub-quadratic time

    • January 09, 2015

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

    Speaker : Johan Nielsen - INRIA Saclay Ile de France

    Reed-Solomon codes have optimal minimum distance and we know efficient encoding and decoding algorithms of quasi-linear complexity in the length. Their main drawback is that their lengths are bounded by the size of the alphabet, i.e. the field over which they are defined. Algebraic geometry codes are a generalisation allowing longer codes on the same alphabet, and one of the most interesting sub[…]

    • Seminar

    • Cryptography

    A heuristic quasi-polynomial algorithm for discrete logarithm

    • October 03, 2014

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

    Speaker : Razvan Basbulescu - LORIA

    in finite fields of small characteristic The difficulty of discrete logarithm computations in fields GF(q^k) depends on the relative sizes of k and q. Until recently all the cases had a sub-exponential complexity of type L(1/3), similar to the complexity of factoring. If n is the bit-size of q^k, then L(1/3) can be approximated by 2^(n^(1/3)). In 2013, Joux designed a new algorithm for constant[…]

    • Seminar

    • Cryptography

    Cryptanalysis of Round-Reduced PRINCE and TWINE

    • March 27, 2015

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

    Speaker : Patrick Derbez - Luxembourg

    NXP Semiconductors and its academic partners challenged the cryptographic community with finding practical attacks on the block cipher they designed, PRINCE. In the first part of this talk we present new attacks on round-reduced PRINCE including the ones which won the challenge in the 6 and 8-round categories --- the highest for which winners were identified. Our first attacks rely on a meet-in[…]

    • Seminar

    • Cryptography

    Décodage des codes de Reed-Solomon et logarithme discret dans

    • March 21, 2014

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

    Speaker : Daniel Augot - INRIA Saclay

    Alors que le problème associé au décodage des Reed-Solomon est connu pour être NP-complet, on sait pas bien quelles sont les instances difficiles, ni si les codes de Reed-Solomon standard font partie de ce ces instances.<br/> Dans le but d'analyser les codes standard, Cheng et Wan étudient depuis 2004 comment le logarithme discret sur les corps non premiers se réduit à un certain problème de[…]

    • Seminar

    • Cryptography

    Cyclic and quasi-cyclic separable Goppa codes

    • November 14, 2014

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

    Speaker : Sergey Bezzateev - Université d'État de Saint-Pétersbourg

    Overview of recent results in constructions of cyclic and quasi-cyclic Goppa codes. Classical and generalized Goppa codes are considered. Subclasses of embedded optimal quasi-cyclic Goppa codes with improvement parameters are presented.

    • Seminar

    • Cryptography

    Decoding interleaved Gabidulin codes and skew complexity of sequences.

    • May 23, 2014

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

    Speaker : Vladimir Sidorenko - Univ. Ulm

    Gabidulin codes are the rank metric analogues of Reed?Solomon codes and have found many applications including network coding and cryptography. Interleaving or the direct sum of Gabidulin codes allows both decreasing the redundancy and increasing the error correcting capability for network coding. We consider a transform domain algorithm correcting both errors and erasures with interleaved[…]
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