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764 résultats
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Séminaire
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Cryptographie
On Rejection Sampling in Lyubashevsky's Signature Scheme
Orateur : Julien Devevey - ENS de Lyon
Lyubashevsky’s signatures are based on the Fiat-Shamir with aborts paradigm, whose central ingredient is the use of rejection sampling to transform (secret-key-dependent) signature samples into samples from a secret-key-independent distribution. The choice of these two underly- ing distributions is part of the rejection sampling strategy, and various instantiations have been considered up to this[…] -
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Séminaire
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Cryptographie
Syndrome Decoding in the Head – Shorter Signatures from Zero-Knowledge proofs
Orateur : Thibauld Feneuil - CryptoExperts et Sorbonne Université
In this talk, I will present a new zero-knowledge proof of knowledge for the syndrome decoding (SD) problem on random linear codes. Instead of using permutations like most of the existing protocols, we rely on the MPC-in-the-head paradigm in which we reduce the task of proving the low Hamming weight of the SD solution to proving some relations between specific polynomials. Specifically, we propose[…] -
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Séminaire
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Cryptographie
Elliptic curves for SNARKs
Orateur : Youssef El Housni - LIX
At CANS’20, El Housni and Guillevic introduced a new 2-chain of pairing-friendly elliptic curves for recursive zero-knowledge Succinct Non-interactive ARguments of Knowledge (zk-SNARKs) made of the former BLS12-377 curve (a Barreto–Lynn–Scott curve over a 377- bit prime field) and the new BW6-761 curve (a Brezing–Weng curve of embedding degree 6 over a 761-bit prime field). First we generalise the[…] -
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Séminaire
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Cryptographie
The Revival of Quadratic Fields Cryptography
Orateur : Guilhem Castagnos - Université Bordeaux 1
More than 30 years ago, Buchmann and Williams proposed using ideal class groups of imaginary quadratic fields in cryptography with a Diffie-Hellman style key exchange protocol. After several twists, there has been in recent years a new interest in this area. This rebirth is mainly due to two features. First, class groups of imaginary quadratic fields allow the design of cryptographic protocols[…] -
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Séminaire
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Cryptographie
On the hardness of the NTRU problem
Orateur : Alice Pellet-Mary - CNRS, Institut Mathématiques de Bordeaux
The NTRU problem is an algorithmic problem over structured lattices that was introduced by Hoffstein, Pipher, and Silverman more than 20 years ago, and which has been used to construct various cryptographic primitives. However, its relation to other lattice problems is still not well understood.<br/> In this talk, we will describe different variants of the NTRU problem, and study how they compare[…] -
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Séminaire
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Cryptographie
Traceable Constant-Size Multi-Authority Credentials
Orateur : Chloé Hébant - ENS
Many attribute-based anonymous credential (ABC) schemes have been proposed allowing a user to prove the possession of some attributes, anonymously. They became more and more practical with, for the most recent papers, a constant-size credential to show a subset of attributes issued by a unique credential issuer. However, proving possession of attributes coming from K different credential issuers[…] -