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709 résultats
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Séminaire
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Cryptographie
On Error Correction for Physical Unclonable Functions
Orateur : Sven Muelich - Institute of Communications Engineering, Ulm University
Cryptographic applications require random, unique and unpredictable keys. Since most cryptosystems need to access the key several times, it usually has to be stored permanently. This is a potential vulnerability regarding security, even if a protected memory is used as key storage. Implementing secure key generation and storage is therefore an important and challenging task which can be[…] -
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Séminaire
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Cryptographie
A heuristic quasi-polynomial algorithm for discrete logarithm
Orateur : Razvan Basbulescu - LORIA
in finite fields of small characteristic The difficulty of discrete logarithm computations in fields GF(q^k) depends on the relative sizes of k and q. Until recently all the cases had a sub-exponential complexity of type L(1/3), similar to the complexity of factoring. If n is the bit-size of q^k, then L(1/3) can be approximated by 2^(n^(1/3)). In 2013, Joux designed a new algorithm for constant[…] -
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Séminaire
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Cryptographie
Keep your friends close with distance-bounding protocols
Orateur : Maria Cristina Onete - IRISA
Authentication protocols, run between a prover and a verifier, allow the verifier to check the legitimacy of the prover. A legitimate prover should always authenticate (the correctness requirement), while illegitimate parties (adversaries) should not authenticate (the soundness or impersonation resistance requirement). Secure authentication protocols thwart most Man-in-the-Middle (MIM) attacks,[…] -
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Séminaire
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Cryptographie
Broadcast encryption: combinatorial vs. algebraic methods
Orateur : Duong-Hieu Phan - ENS
We consider a generalisation of the encryption from "one-to-one'' to "one-to-many'' communication, i.e. broadcast encryption. The objective is to allow a center to send secret messages to a large number of receivers. The security notion in “one-to-many” communications needs to be extended beyond the notion of confidentiality in “one-to-one” encryption in order to meet practical requirements. Two[…] -
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Séminaire
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Cryptographie
Un algorithme pour trouver toutes les formules calculant une application bilinéaire.
Orateur : Nicolas Estibal - IRISA
La multiplication est une opération arithmétique coûteuse comparativement à l'addition. Aussi il est intéressant, étant donné une application, de minimiser le nombre de produits à effectuer pour la calculer. Dans cette étude, nous nous restreignons au cas des applications bilinéaires.<br/> En effet, parmi les applications bilinéaires, nous étions intéressés en premier lieu par la multiplication[…] -
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Séminaire
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Cryptographie
GGHLite: More Efficient Multilinear Maps from Ideal Lattices
Orateur : 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[…] -