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679 résultats
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Séminaire
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Cryptographie
Grost Distinguishing Attack: A new rebound attack of an AES-like permutation
Orateur : Victor Cauchois - DGA et IRMAR
Grostl est une fonction de hachage finaliste de la compétition SHA-3. Elle est dotée d'une preuve de sécurité qui assure sa résistance aux attaques en collision, pré-image et seconde pré-image sous l'hypothèse que deux permutations internes sont idéales. Ces permutations, 14 tours d'un SPN, calques de l'AES, présentent une structure sensible aux attaques rebond. Ces attaques sont des attaques[…] -
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Séminaire
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Cryptographie
Discrete logarithm computation in finite fields GF(p^k) with NFS
Orateur : Aurore Guillevic - INRIA
Pairings on elliptic curves are involved in signatures, NIZK, and recently in blockchains (ZK-SNARKS).<br/> These pairings take as input two points on an elliptic curve E over a finite field, and output a value in an extension of that finite field. Usually for efficiency reasons, this extension degree is a power of 2 and 3 (such as 12,18,24), and moreover the characteristic of the finite field has[…] -
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Séminaire
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Cryptographie
Improving greedy nonrandomness detectors for stream ciphers
Orateur : Paul Stankovski - Université de Lund
We consider the problem of designing distinguishers and nonrandomness detectors for stream ciphers using the maximum degree monomial test. We construct an improved algorithm to determine the subset of key and IV-bits used in the test. The algorithm is generic, and can be applied to any stream cipher. In addition to this, the algorithm is highly tweakable, and can be adapted depending on the[…] -
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Séminaire
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Cryptographie
Towards the Implementation of Efficient and Distributable Pairing-based Crypto Library
Orateur : Al-Amin Khandaker - Okayama University
Pairing-based cryptography is popular among the cryptographic protocol researchers for its eccentric provable security. Protocol side researchers often see pairing as a black box. They often need to test the correctness of their proposal. Typically, mathematicians and cryptography engineers try to make the underlying operations of pairing-based crypto efficient. In addition, different types of[…] -
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Séminaire
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Cryptographie
Encryption Switching Protocols
Orateur : Geoffroy Couteau - ENS
(Joint work with Thomas Peters, and David Pointcheval) We put forth a novel cryptographic primitive: encryption switching protocol (ESP), allowing to switch between two encryption schemes. Intuitively, this two-party protocol converts given ciphertexts from one scheme into ciphertexts of the same messages in the other scheme, for any polynomial number of switches, in any direction. Although ESP is[…] -
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Séminaire
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Cryptographie
Adaptive Oblivious Transfer with Access Control for NC1 from LWE
Orateur : Fabrice Mouhartem - Ens Lyon
Adaptive oblivious transfer (OT) is a protocol where a sender initially commits to a database M_1, …, M_N. Then, a receiver can query the sender up to k times with private indexes ρ_1, …, ρ_k so as to obtain M_{ρ_1}, …, M_{ρ_k} and nothing else. Moreover, for each i ∈ [k], the receiver’s choice ρ_i may depend on previously obtained messages {M_{ρ_j}}_{j< i} . Oblivious transfer with access control[…] -