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634 résultats

    • Séminaire

    • Cryptographie

    Shorter Lattice-Based Fiat-Shamir Signatures

    • 26 janvier 2024

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

    Orateur : Julien Devevey - ANSSI

    We present HAETAE (Hyperball bimodAl modulE rejecTion signAture schemE), a new lattice-based signature scheme, which we submitted to the Korean Post-Quantum Cryptography Competition for standardization. Like the NIST-selected Dilithium signature scheme, HAETAE is based on the Fiat-Shamir with Aborts paradigm, but our design choices target an improved complexity/compactness compromise that is[…]
    • Séminaire

    • Cryptographie

    Ind-cpa-d insecurity of approximate and exact homomorphic encryption schemes

    • 29 mars 2024

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

    Orateur : Elias Suvanto - Cryptolab

    Fully Homomorphic Encryption enables the evaluation of arbitrary circuits over encrypted data while maintaining the confidentiality of the underlying messages. It greatly enhances functionality but also comes with security challenges for some applications like Threshold FHE. While the standard IND-CPA security is sufficient against honest but curious adversaries, a stronger security notion called[…]
    • Séminaire

    • Cryptographie

    An extension of Overbeck’s attack with an application to cryptanalysis of Twisted Gabidulin-based schemes.

    • 06 octobre 2023

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

    Orateur : Ilaria Zappatore - XLIM

    In this talk, I will discuss the decoding of Gabidulin and related codes from a cryptographic point of view, pointing out that these codes can be decoded solely from the knowledge of a generator matrix. I will also present an extension of Gibson and Overbeck attacks on the generalized GPT encryption scheme (instantiated with the Gabidulin code) for different ranks of the distortion matrix. Finally[…]
    • Séminaire

    • Cryptographie

    Side channel analysis against AEAD lightweight cryptography

    • 24 mai 2024

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

    Orateur : Modou SARRY - IMT Atlantique

    Les dispositifs interconnectés tels que les réseaux de capteurs, la santé, les systèmes de contrôle distribués, l’internet des objets et les systèmes cyber-physiques sont de plus en plus répandus. Cette transition vers de petits appareils engendre de nouvelles préoccupations en matière de sécurité et de vie privée, car de nombreux algorithmes cryptographiques classiques ne répondent pas toujours[…]
    • Séminaire

    • Cryptographie

    Pseudorandom Correlation Generators from the Quasi-Abelian Decoding Problem

    • 19 janvier 2024

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

    Orateur : Clément Ducros - IRIF

    Secure multi-party computing often enhances efficiency by leveraging correlated randomness. Recently, Boyle et al. showcased the effectiveness of pseudorandom correlation generators (PCGs) in producing substantial correlated (pseudo)randomness, specifically for two-party random oblivious linear evaluations (OLEs). This process involves minimal interactions and subsequent local computations,[…]
    • Séminaire

    • Cryptographie

    On some efficiency aspects of the CKKS fully homomorphic encryption scheme

    • 17 mai 2024

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

    Orateur : Damien Stehlé - Cryptolab

    Fully homomorphic encryption (FHE) is a form of encryption that allows arbitrary computations on data without requiring to decrypt the ciphertexts. Among the diverse FHE schemes, CKKS is designed to efficiently perform computations on real numbers in an encrypted state. Interestingly, Drucker et al [J. Cryptol.] recently proposed an efficient strategy to use CKKS in a black-box manner to perform[…]