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702 results

    • Seminar

    • Cryptography

    Speeding up Fully Homomorphic Encryption

    • June 10, 2016

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

    Speaker : Marie Paindavoine - Orange Labs

    Access to encrypted data is often “all-or-nothing” : either one has to decrypt everything, or one cannot read anything. Following Gentry’s work in 2009, fully homomorphic encryption has gained more and more attention, in particular because it allows more flexibility on encrypted data access and process. It is now possible to evaluate functions on encrypted data and get only the result – encrypted[…]
    • Seminar

    • Cryptography

    Algorithms for polynomial selection in the number field sieve

    • December 18, 2015

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

    Speaker : Shi Bai - Australian National University

    The general number field sieve (GNFS) is the most efficient algorithm known for factoring large integers. It consists of several stages, the first one being polynomial selection. The running-time of the number field sieve depends on the quality of the chosen polynomials. The quality of the chosen polynomials can be modeled in terms of size and root properties. In this talk, we will describe some[…]
    • Seminar

    • Cryptography

    Symmetric Encryption Scheme adapted to Fully Homomorphic Encryption Scheme

    • September 30, 2016

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

    Speaker : Pierrick Méaux - ENS Paris

    Fully Homomorphic Encryption is a powerful cryptographic construction, enabling to securely compute all functions on encrypted data, and decrypt the result of the function applied on the real data.<br/> This construction allows to securely delegate computation, which is a very important property with the increasing of the Cloud computing. Many client-server applications are appearing, all needing[…]
    • Seminar

    • Cryptography

    GGHLite: More Efficient Multilinear Maps from Ideal Lattices

    • December 05, 2014

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

    Speaker : Adeline Langlois - ENS Lyon

    The GGH Graded Encoding Scheme (of Garg, Gentry and Halevi), based on ideal lattices, is the first plausible approximation to a cryptographic multilinear map. Unfortunately, using the security analysis the authors provided, the scheme requires very large parameters to provide security for its underlying encoding re-randomization process. Our main contributions are to formalize, simplify and[…]
    • Seminar

    • Cryptography

    Points rationnels sur une surface cubique

    • January 24, 2014

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

    Speaker : Jenny Cooley - University of Warwick

    Soit F_q un corps fini à au moins 13 éléments. Soit S une surface cubique non singulière sur laquelle il y a au moins une droite rationnelle incluse. Il existe une façon de générer les points rationnels en utilisant des opérations tangentes et sécantes qui est similaire à la loi de composition du groupe de points d'une courbe elliptique. Dans cet exposé, nous utilisons le principe des tiroirs pour[…]
    • Seminar

    • Cryptography

    Attaques quantiques contre les chiffrements par bloc composés

    • March 13, 2015

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

    Speaker : Marc Kaplan - Télécom ParisTech

    Nous étudions l'amplification de la sécurité obtenue en composant des chiffrements par bloc indépendants. Dans le cas classique, l'attaque Meet-in-the-middle est une attaque générique contre ces constructions. Si le temps nécessaire pour briser un chiffrement par bloc est t, alors cette attaque permet de briser deux chiffrements par bloc en un temps seulement 2t, alors qu'un cryptographe naïf[…]