599 résultats
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Quelques aspects algorithmiques de la cryptographie
Orateur : David Lubicz - DGA et Université Rennes I
La cryptographie à clef publique, qui fut inventée dans les années soixante-dix par W. Diffie et M. Hellman, apporte par rapport à la cryptographie symétrique un certain nombre de fonctionnalités particulièrement intéressantes pour les applications pratiques. Sa mise en oeuvre repose le plus souvent sur la difficulté calculatoire de certains problèmes issus de la théorie des nombres. De là, on[…] -
How to break Remote Keyless Entry Systems.
Orateur : Timo Kasper - Bochum
KeeLoq remote keyless entry systems are widely used for access control purposes such as garage openers or car door systems. The talk will present the first successful differential power analysis attacks on numerous commercially available products employing KeeLoq code hopping. They allow for efficiently revealing both the secret key of a remote transmitter and the manufacturer key stored in a[…] -
Cube Attacks on Tweakable Black Box Polynomials
Orateur : Adi Shamir - Weizmann Institute of Science
In this talk I will introduce a new kind of attack on cryptosystems which can be represented by an (unknown) low degree polynomial with tweakable public variables such as a plaintext or IV and fixed secret variables such as a key. Its complexity is exponential in the degree but only polynomial in the key size, and it was successfully applied to several concrete schemes. In particular, for Trivium[…] -
Cryptanalysis of Two McEliece Cryptosystems Based on Quasi-Cyclic Codes
Orateur : Ayoub Otmani - Ensicaen
We cryptanalyse here two variants of the McEliece cryptosystem based on quasi-cyclic codes. Both aim at reducing the key size by restricting the public and secret generator matrices to be in quasi-cyclic form. The first variant considers subcodes of a primitive BCH code. The aforementioned constraint on the public and secret keys implies to choose very structured permutations. We prove that this[…] -
RSA problems with Lattice Reduction
Orateur : Alexander May - Technische Universität Darmstadt
This survey addresses the problems of factoring and inverting the RSA function. We define practically relevant relaxed instances of these problems that can be solved in polynomial time. These problem instances are modelled by polynomial equations with small roots. In order to recover the roots, we make use of a method due to Coppersmith which is in turn based on the famous LLL lattice reduction.[…] -
Fountain codes
Orateur : Amin Shokrollahi - EPFL
A Fountain code is a code of fixed dimension and a limitless block-length. This is a new class of codes with very interesting applications. In this talk I will show how Fountain codes can be applied to the problem of reliable, robust, and speedy transmission of data over a heterogeneous network from one or multiple transmitters to one or multiple receivers. I will then talk about applications to[…]