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654 results

    • Seminar

    • Cryptography

    New uses in Symmetric Cryptography: from Cryptanalysis to Designing

    • May 20, 2022

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

    Speaker : Clémence Bouvier - INRIA

    New symmetric primitives are being designed to be run in abstract settings such as Multi-Party Computations (MPC) or Zero-Knowledge (ZK) proof systems. More particularly, these protocols have highlighted the need to minimize the number of multiplications performed by the primitive in large finite fields.<br/> As the number of such primitives grows, it is important to better understand the[…]
    • Seminar

    • Cryptography

    PMNS for efficient arithmetic and small memory cost

    • June 10, 2022

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

    Speaker : Fangan Yssouf Dosso - Ecole des Mines de Saint-Etienne

    The Polynomial Modular Number System (PMNS) is an integer number system which aims to speed up arithmetic operations modulo a prime p. Such a system is defined by a tuple (p, n, g, r, E), where p, n, g and r are positive integers, E is a monic polynomial with integer coefficients, having g as a root modulo p. Most of the work done on PMNS focus on polynomials E such that E(X) = X^n – l, where l is[…]
    • Seminar

    • Cryptography

    The Revival of Quadratic Fields Cryptography

    • January 17, 2020

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

    Speaker : Guilhem Castagnos - Université Bordeaux 1

    More than 30 years ago, Buchmann and Williams proposed using ideal class groups of imaginary quadratic fields in cryptography with a Diffie-Hellman style key exchange protocol. After several twists, there has been in recent years a new interest in this area. This rebirth is mainly due to two features. First, class groups of imaginary quadratic fields allow the design of cryptographic protocols[…]
    • Seminar

    • Cryptography

    On the hardness of the NTRU problem

    • October 08, 2021

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

    Speaker : Alice Pellet-Mary - CNRS, Institut Mathématiques de Bordeaux

    The NTRU problem is an algorithmic problem over structured lattices that was introduced by Hoffstein, Pipher, and Silverman more than 20 years ago, and which has been used to construct various cryptographic primitives. However, its relation to other lattice problems is still not well understood.<br/> In this talk, we will describe different variants of the NTRU problem, and study how they compare[…]
    • Seminar

    • Cryptography

    Implicit proofs of membership

    • March 13, 2020

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

    Speaker : Olivier Blazy - Université Limoges

    Smooth hash proof systems have been introduced by Cramer and shoup to build compact efficient cca2 encryption in the standard model. Since then, they found applications in a broad range of protocols from oblivious transfer to authenticated key exchange, passing by witness examples.<br/> In this talk, we will start by a panorama of languages that can be managed by such a primitive and then show how[…]
    • Seminar

    • Cryptography

    A Concrete Treatment of Efficient Continuous Group Key Agreement via Multi-Recipient PKEs

    • November 19, 2021

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

    Speaker : Thomas Prest - PQShield

    Continuous group key agreements (CGKAs) are a class of protocols that can provide strong security guarantees to secure group messaging protocols such as Signal and MLS. Protection against device compromise is provided by commit messages: at a regular rate, each group member may refresh their key material by uploading a commit message, which is then downloaded and processed by all the other members[…]