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714 résultats

    • Séminaire

    • Cryptographie

    On weak keys in QC-MDPC schemes

    • 21 février 2020

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

    Orateur : Valentin Vasseur - INRIA

    Quasi-cyclic moderate density parity check (QC-MDPC) codes allow the design of McEliece-like public-key encryption schemes with compact keys and a security that provably reduces to hard decoding problems for quasi-cyclic codes. Because of these features, QC-MDPC have attracted a lot of interest from the cryptographic community. In particular, the BIKE suite of key exchange mechanisms has been[…]
    • Séminaire

    • Cryptographie

    Soutenance de thèse: Theoretical Hardness of Algebraically Structured Learning With Errors

    • 16 novembre 2021

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

    Orateur : Katharina Boudgoust - Rennes

    The main focus of this PhD thesis lies on the computational problem Learning With Errors (LWE). It is a core building block of lattice-based cryptography, which itself is among the most promising candidates to replace current cryptographic protocols once large-scale quantum computers may be available. The contributions of the present work are separated into two different parts. First, we study the[…]
    • Séminaire

    • Cryptographie

    Grost Distinguishing Attack: A new rebound attack of an AES-like permutation

    • 02 mars 2018

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

    Orateur : Victor Cauchois - DGA et IRMAR

    Grostl est une fonction de hachage finaliste de la compétition SHA-3. Elle est dotée d'une preuve de sécurité qui assure sa résistance aux attaques en collision, pré-image et seconde pré-image sous l'hypothèse que deux permutations internes sont idéales. Ces permutations, 14 tours d'un SPN, calques de l'AES, présentent une structure sensible aux attaques rebond. Ces attaques sont des attaques[…]
    • Séminaire

    • Cryptographie

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

    • 01 mars 2019

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

    Orateur : 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[…]
    • Séminaire

    • Cryptographie

    Post-quantum cryptography based on supersingular isogeny problems?

    • 25 octobre 2019

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

    Orateur : Christophe Petit - University of Birmingham

    The security of many cryptographic protocols in use today relies on the computational hardness of mathematical problems such as integer factorization. These problems can be solved using quantum computers, and therefore most of our security infrastructures will become completely insecure once quantum computers are built. Post-quantum cryptography aims at developing security protocols that will[…]
    • Séminaire

    • Cryptographie

    Learning Strikes Again: the Case of the DRS Signature Scheme

    • 09 novembre 2018

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

    Orateur : 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[…]