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679 results

    • Seminar

    • Cryptography

    Number Systems and Cryptography, some examples

    • February 08, 2019

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

    Speaker : Jean-Claude Bajard - Sorbonne Université

    Number systems are behind a lot of implementations. The role of representation is often underrated while its importance in implementation is crucial. We survey here some classes of fundamental systems that could be used in crypotgraphy. We present three main categories:<br/> - systems based on the Chinese Remainder Theorem which enter more generally in the context of polynomial interpolation,<br/[…]
    • Seminar

    • Cryptography

    Quantum security of the Fiat-Shamir transform of commit and open protocols

    • April 26, 2019

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

    Speaker : André Chailloux - INRIA

    Applying the Fiat-Shamir transform on identification schemes is one of the main ways of constructing signature schemes. While the classical security of this transformation is well understood, there are still many cases for which we do not know whether the quantum security holds or not. In this paper, we show that if we start from a commit-and-open identification scheme, where the prover first[…]
    • Seminar

    • Cryptography

    Practical Strategy-Resistant Privacy-Preserving Elections

    • October 19, 2018

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

    Speaker : Quentin Santos - Orange

    Recent advances in cryptography promise to let us run com- plex algorithms in the encrypted domain. However, these results are still mostly theoretical since the running times are still much larger than their equivalents in the plaintext domain. In this context, Majority Judgment is a recent proposal for a new voting system with several interesting practical advantages, but which implies a more[…]
    • Seminar

    • Cryptography

    Cocks-Pinch curves of embedding degree five to eight and optimal ate pairing computation

    • June 21, 2019

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

    Speaker : Simon Masson - Loria, Nancy

    Recent algorithmic improvements of discrete logarithm computation in special extension fields threaten the security of pairing-friendly curves used in practice. A possible answer to this delicate situation is to propose alternative curves that are immune to these attacks, without compromising the efficiency of the pairing computation too much. We follow this direction, and focus on embedding[…]
    • Seminar

    • Cryptography

    Aggregate Cash Systems: A Cryptographic Investigation of Mimblewimble

    • November 30, 2018

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

    Speaker : Michele Orru - ENS

    • Seminar

    • Cryptography

    Isogeny-based cryptography from superspecial genus-2 curves

    • October 18, 2019

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

    Speaker : Wouter Castryck - KU Leuven

    I will report on some first attempts to do isogeny-based cryptography in genus 2. More precisely, we will use isogeny graphs of superspecial principally polarized abelian surfaces over GF(p^2) for constructing variants of Charles, Goren and Lauter's hash function and of Jao and De Feo's SIDH key exchange protocol, both of which use supersingular elliptic curves over GF(p^2). This will be largely[…]