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633 results

    • Seminar

    • Cryptography

    Shorter Lattice-Based Fiat-Shamir Signatures

    • January 26, 2024

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

    Speaker : 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[…]
    • Seminar

    • Cryptography

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

    • March 29, 2024

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

    Speaker : 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[…]
    • Seminar

    • Cryptography

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

    • October 06, 2023

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

    Speaker : 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[…]
    • Seminar

    • Cryptography

    Pseudorandom Correlation Generators from the Quasi-Abelian Decoding Problem

    • January 19, 2024

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

    Speaker : 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,[…]
    • Seminar

    • Cryptography

    On some efficiency aspects of the CKKS fully homomorphic encryption scheme

    • May 17, 2024

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

    Speaker : 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[…]
    • Seminar

    • Cryptography

    Evaluation embarquée de l'entropie d'un générateur d'aléa pour la cryptographie

    • January 12, 2024

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

    Speaker : David Lubicz - DGA et IRMAR

    Dans cet exposé, nous présentons une méthode de mesure embarquée de la composante thermique du jitter de phase d'un couple d'anneaux d'oscillateurs : cette mesure est nécessaire pour calculer le taux d'entropie d'un générateur d'aléa physique basé sur des anneaux oscillants. La précision de cette mesure dont le principe repose sur un algorithme de type Monte-Carlo dépend de l' équidistribution de[…]