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669 results
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Seminar
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Cryptography
Introduction to Secure Multi-Party Computation
Speaker : Martin Hirt - ETH Zurich
Consider a set of $n$ players, each holding a value $x_1,...,x_n$, and an $n$-ary function $f$, specified as an arithmetic circuit over a finite field. How can the players compute $y=f(x_1,...,x_n)$ in such a way that no (small enough) set of dishonest players obtains any joint information about the input values of the honest players (beyond of what they can infer from $y$)? In this talk, we[…] -
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Seminar
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Cryptography
Computationally Sound Security Proof using Formal Models
Speaker : Véronique Cortier - LORIA
Since the 1980s, two approaches have been developed for analyzing security protocols. One of the approaches relies on a computational model that considers issues of complexity and probability. This approach captures a strong notion of security, guaranteed against all probabilistic polynomial-time attacks. The other approach relies on a symbolic model of protocol executions in which[…] -
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Seminar
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Cryptography
Sur le rang de tordues quadratiques de courbes elliptiques sur
Speaker : Emmanuel Kowalski - Université Bordeaux I
La distribution du rang de familles de courbes elliptiques sur un corps de fonction sur un corps fini est théoriquement mieux comprise que dans le cas d'un corps de nombre. En particulier, dans le cas de familles de tordues quadratiques d'une courbe fixée, il est possible de montrer que le nombre de tordues dont le rang est plus grand que ce qu'impose l'équation fonctionnelle est trés petit. Les[…] -
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Seminar
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Cryptography
Interpolation polynomiale multivariée, codes et cryptographie (travail en collaboration avec O. Ruatta)
Speaker : Philippe Gaborit - Université de Limoges
Dans cet exposé nous nous intéressons à l'interpolation polynomiale multivariée et à ses applications. Nous présenterons tout d'abord des applications connues comme le décodage en liste des codes de Reed-Solomon (pour lequel Madhu Sudan a recu le prix Nevanlinna), mais aussi des applications nouvelles comme le décodage en liste des effacements des codes de Reed-Muller ou encore l'application au[…] -
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Seminar
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Cryptography
Blackbox Secret Sharing from Primitive Sets in Algebraic Number Fields
Speaker : Rolnald Cramer - CWI, Amsterdam & Mathematical Insitute, Leiden University
A {\em black-box} secret sharing scheme (BBSSS) for a given access structure works in exactly the same way over any finite Abelian group, as it only requires black-box access to group operations and to random group elements. In particular, there is no dependence on e.g.\ the structure of the group or its order. The expansion factor of a BBSSS is the length of a vector of shares (the number of[…] -
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Seminar
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Cryptography
Cryptography in the Bounded Quantum-Storage Model
Speaker : Serge Fehr - CWI Amsterdam
Most of todays cryptography relies on the assumption that a potential attacker cannot solve some computational problem (e.g. factor a large integer). It has been shown in the early 80's that with the use of quantum-mechanical effects, certain cryptographic tasks can be done unconditionally, i.e., secure against computationally unbounded attackers: Quantum-cryptography, and with it the hope that (m[…] -