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670 résultats
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Séminaire
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Cryptographie
Same-Values Analysis on Elliptic Curve Cryptography
Orateur : Cédric Murdica - Secure-IC
Elliptic Curve Cryptography (ECC) is believed to be unbreakable in the black box model, where the cryptanalyst has access to inputs and outputs only. However, it is not enough if the cryptosystem is embedded on a device that is physically accessible to potential attackers. In addition to inputs and outputs, the attacker can study the physical behaviour of the device such as the execution time or[…] -
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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
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
Learning with Errors in the Exponent
Orateur : özgür Dagdelen - Darmstadt University
We initiate the study of a novel class of group-theoretic intractability problems. Inspired by the theory of learning in presence of errors [Regev, STOC'05] we ask if noise in the exponent amplifies intractability. We put forth the notion of Learning with Errors in the Exponent (LWEE) and rather surprisingly show that various attractive properties known to ex- clusively hold for lattices carry[…] -
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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[…] -
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Séminaire
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Cryptographie
Beyond the black and grey box
Orateur : Yoni De Mulder - University of Leuven
In the white-box attack context, i.e., the setting where an implementation of a cryptographic algorithm is executed on an untrusted open platform, the adversary has full access to the implementation and its execution environment. As a result, the adversary is much more powerful than in a traditional black-box environment in which the adversary has only access to the inputs and outputs of a[…] -