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633 results

    • Seminar

    • Cryptography

    Discrete logarithm computation in finite fields GF(p^k) with NFS

    • March 01, 2019

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

    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[…]
    • Seminar

    • Cryptography

    Cryptography based on rank metric codes

    • November 08, 2019

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

    Speaker : Nicolas Aragon - Université de Limoges, exceptionnellement salle Jersey à l'ISTIC

    In the past few years, the interest for rank metric based cryptography has drastically increased, especially since the beginning of the NIST Post-Quantum Cryptography standardization process : five rank metric based proposals were submitted to the first round. This talk will present the different approaches and tradeoffs for building Key Encapsulation Mechanisms and Public Key Encryption schemes[…]
    • Seminar

    • Cryptography

    Learning With Errors and Extrapolated Dihedral Cosets Problem

    • February 23, 2018

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

    Speaker : Weiqiang Wen - ENS de Lyon

    The hardness of the learning with errors (LWE) problem is one of the most fruitful resources of modern cryptography. In particular, it is one of the most prominent candidates for secure post-quantum cryptography. Understanding its quantum complexity is therefore an important goal. We show that under quantum polynomial time reductions, LWE is equivalent to a relaxed version of the dihedral coset[…]
    • Seminar

    • Cryptography

    Homomorphic Signatures on Randomizable Ciphertexts

    • May 10, 2019

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

    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[…]
    • Seminar

    • Cryptography

    Learning Strikes Again: the Case of the DRS Signature Scheme

    • November 09, 2018

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

    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[…]
    • Seminar

    • Cryptography

    Soutenance de thèse (exceptionnellement jeudi à 14h): Couches de diffusion linéaires à partir de matrices MDS

    • December 13, 2018

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

    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[…]