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633 results

    • 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

    Generic Attack on Duplex-Bases AEAD Modes using Random Function Statistics

    • September 22, 2023

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

    Speaker : Rachelle Heim Boissier - Inria

    Duplex-based authenticated encryption modes with a sufficiently large key length are proven to be secure up to the birthday bound 2^(c/2), where c is the capacity. However this bound is not known to be tight and the complexity of the best known generic attack, which is based on multicollisions, is much larger: it reaches 2^c/α where α represents a small security loss factor. There is thus an[…]
    • 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[…]
    • Seminar

    • Cryptography

    Recent advances in post-quantum signatures based on the MPC-in-the-Head paradigm

    • March 22, 2024

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

    Speaker : Thibauld Feneuil - CryptoExperts

    Zero-knowledge proofs of knowledge are useful tools for designing signature schemes. Among the existing techniques, the MPC-in-Head (MPCitH) paradigm provides a generic framework to build quantum-resilient proofs using techniques from secure multiparty computation. This paradigm has recently been improved in a series of works which makes it an effective and versatile tool. In this talk, I will[…]