522 results

  • Euclidean lattice and PMNS: arithmetic, redundancy and equality test

    • January 31, 2025 (13:45 - 14:45)

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

    Speaker : Fangan Yssouf Dosso - Laboratoire SAS, École des Mines de Saint-Étienne

    The Polynomial Modular Number System (PMNS) is an integer number system that aims to speed up arithmetic operations modulo a prime number p. This system is defined by a tuple (p, n, g, r, E), where p, n, g and r are positive integers, and E is a polynomial with integer coefficients, having g as a root modulo p. Arithmetic operations in PMNS rely heavily on Euclidean lattices. Modular reduction in[…]
  • Updatable Encryption from Group Actions

    • January 24, 2025 (13:45 - 14:45)

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

    Speaker : Maxime Romeas - ANSSI

    Updatable Encryption is a variant of symmetric encryption that allows to rotate the encryption key in the outsourced storage setting while minimizing the bandwith used. Indeed, any third party can update ciphertexts to the new key using a token provided by the key holder. UE schemes aim at providing strong confidentiality guarantees against adversaries that can corrupt keys and tokens.  In this[…]
  • Séminaire C2

    • January 17, 2025 (11:30 - 17:00)

    • Nancy

    11h30  Katharina Boudgoust (CR CNRS, LIRMM) : The Power of NAPs: Compressing OR-Proofs via Collision-Resistant HashingProofs of partial knowledge allow for proving the validity of t out of n different statements without revealing which ones those are. In this presentation, we describe a new approach for transforming certain proofs system into new ones that allows for proving partial knowledge. The[…]
  • Post-quantum Group-based Cryptography

    • January 10, 2025 (13:45 - 14:45)

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

    Speaker : Delaram Kahrobaei - The City University of New York

    Group-based cryptography is a relatively new family in post-quantum cryptography, with high potential. I will give a general survey of the status of post-quantum group-based cryptography and present some recent results.In the second part of my talk, I speak about Post-quantum hash functions using special linear groups. This hash function is a generalization of Tillich-Zemor hash function as well[…]
  • Polytopes in the Fiat-Shamir with Aborts Paradigm

    • November 29, 2024 (13:45 - 14:45)

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

    Speaker : Hugo Beguinet - ENS Paris / Thales

    The Fiat-Shamir with Aborts paradigm (FSwA) uses rejection sampling to remove a secret’s dependency on a given source distribution.  Recent results revealed that unlike the uniform distribution in the hypercube, both the continuous Gaussian and the uniform distribution within the hypersphere minimise the rejection rate and the size of the proof of knowledge. However, in practice both these[…]
    • Cryptography

    • Asymmetric primitive

    • Mode and protocol

  • Computational assumptions in the quantum world

    • November 22, 2024 (13:45 - 14:45)

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

    Speaker : Alex Bredariol Grilo - LIP6 (CNRS / Sorbonne Université)

    QKD is a landmark of how quantum resources allow us to implement cryptographicfunctionalities with a level of security that is not achievable only with classical resources.However, key agreement is not sufficient to implement all functionalities of interest, and it iswell-known that they cannot be implemented with perfect security, even if we have accessto quantum resources. Thus, computational[…]
    • Cryptography