627 résultats
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Disjunctions for Hash Proof Systems: New Constructions and Applications
Orateur : Fabrice Ben Hamouda - ENS
Hash Proof Systems were first introduced by Cramer and Shoup (Eurocrypt'02) as a tool to construct efficient chosen-ciphertext-secure encryption schemes. Since then, they have found many other applications, including password authenticated key exchange, oblivious transfer, and zero-knowledge arguments. One of the aspects that makes hash proof systems so interesting and powerful is that they can be[…] -
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[…] -
Constructive cryptography and composability; de-constructing TLS
Orateur : Cristina Onete - IRISA, Université Rennes 1
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Is there an L(1/4) algorithm for the discrete logarithm problem in algebraic curves?
Orateur : Maike Massierer - LORIA
The function field sieve, an algorithm of subexponential complexity L(1/3) that computes discrete logarithms in finite fields, has recently been improved to an L(1/4) algorithm, and subsequently to a quasi-polynomial time algorithm. Since index calculus algorithms for computing discrete logarithms in Jacobians of algebraic curves are based on very similar concepts and results, the natural question[…] -
Cryptanalysis of Round-Reduced PRINCE and TWINE
Orateur : Patrick Derbez - Luxembourg
NXP Semiconductors and its academic partners challenged the cryptographic community with finding practical attacks on the block cipher they designed, PRINCE. In the first part of this talk we present new attacks on round-reduced PRINCE including the ones which won the challenge in the 6 and 8-round categories --- the highest for which winners were identified. Our first attacks rely on a meet-in[…] -
Functional Encryption: A novel paradigm for public-key encryption.
Orateur : Angelo De Caro - ENS
Whereas, in traditional public-key encryption, decryption is an all-or-nothing affair (i.e., a receiver is either able to recover the entire message using its key, or nothing), functional encryption enables fine-grained access control and computation on encrypted data, as required to protect data in the cloud.<br/> In the first part of the talk, we provide an introduction to functional encryption[…]