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665 résultats

    • Séminaire

    • Cryptographie

    Tightly Secure CCA-Secure Encryption without Pairings.

    • 25 novembre 2016

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

    Orateur : Romain Gay - ENS

    (Joint work with Dennis Hofheinz, Eike Kiltz and Hoeteck Wee) We present the first CCA-secure public-key encryption scheme based on DDH where the security loss is independent of the number of challenge ciphertexts and the number of decryption queries. Our construction extends also to the standard k-Lin assumption in pairing-free groups, whereas all prior constructions starting with Hofheinz and[…]
    • Séminaire

    • Cryptographie

    Adaptive Oblivious Transfer with Access Control for NC1 from LWE

    • 16 juin 2017

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

    Orateur : Fabrice Mouhartem - Ens Lyon

    Adaptive oblivious transfer (OT) is a protocol where a sender initially commits to a database M_1, …, M_N. Then, a receiver can query the sender up to k times with private indexes ρ_1, …, ρ_k so as to obtain M_{ρ_1}, …, M_{ρ_k} and nothing else. Moreover, for each i ∈ [k], the receiver’s choice ρ_i may depend on previously obtained messages {M_{ρ_j}}_{j< i} . Oblivious transfer with access control[…]
    • Séminaire

    • Cryptographie

    Low-Complexity Cryptographic Hash Functions

    • 13 janvier 2017

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

    Orateur : Vinod Vaikuntanathan - Massachusetts Institute of Technology

    Cryptographic hash functions are efficiently computable functions that shrink a long input into a shorter output while achieving some of the useful security properties of a random function. The most common type of such hash functions is collision resistant hash functions (CRH), which prevent an efficient attacker from finding a pair of inputs on which the function has the same output.<br/> Despite[…]
    • Séminaire

    • Cryptographie

    Middle-Product Learning With Errors

    • 13 octobre 2017

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

    Orateur : Miruna Rosca - ENS de Lyon

    We introduce a new variant MP-LWE of the Learning With Errors problem (LWE) making use of the Middle Product between polynomials modulo an integer q. We exhibit a reduction from the Polynomial-LWE problem (PLWE) parametrized by a polynomial f, to MP-LWE which is defined independently of any such f. The reduction only requires f to be monic with constant coefficient coprime with q. It incurs a noise[…]
    • Séminaire

    • Cryptographie

    Towards the Implementation of Efficient and Distributable Pairing-based Crypto Library

    • 01 décembre 2017

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

    Orateur : Al-Amin Khandaker - Okayama University

    Pairing-based cryptography is popular among the cryptographic protocol researchers for its eccentric provable security. Protocol side researchers often see pairing as a black box. They often need to test the correctness of their proposal. Typically, mathematicians and cryptography engineers try to make the underlying operations of pairing-based crypto efficient. In addition, different types of[…]
    • Séminaire

    • Cryptographie

    Coercion-resistant Internet voting made practical

    • 03 mars 2017

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

    Orateur : Jacques Traore - Orange Labs

    Internet voting offers a better voting experience since voters can cast their votes from their computers or even smartphones. By eliminating the need to visit polling places, it may attract more voters and thus increase voter turnout. However, it is still not widely spread owing to many inherent concerns such as risks entailed by the lack of private polling booths. Indeed, this may ease coercion[…]