526 results
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Constant-time lattice reduction for SQIsign
Speaker : Sina Schaeffler - IBM Research
SQIsign is an isogeny-based signature scheme which has recently advanced to round 2 of NIST's call for additional post-quantum signatures. A central operation in SQIsign is lattice reduction of special full-rank lattices in dimension 4. As these input lattices are secret, this computation must be protected against side-channel attacks. However, known lattice reduction algorithms like the famous[…] -
Efficient zero-knowledge proofs and arguments in the CL framework
Speaker : Agathe Beaugrand - Institut de Mathématiques de Bordeaux
The CL encryption scheme, proposed in 2015 by Castagnos and Laguillaumie, is a linearly homomorphic encryption scheme, based on class groups of imaginary quadratic fields. The specificity of these groups is that their order is hard to compute, which means it can be considered unknown. This particularity, while being key in the security of the scheme, brings technical challenges in working with CL,[…] -
Pairing-Free Blind Signatures from Standard Assumptions in the ROM
Speaker : Ky Nguyen - ENS
Blind Signatures are a useful primitive for privacy preserving applications such as electronic payments, e-voting, anonymous credentials, and more. However, existing practical blind signature schemes based on standard assumptions require either pairings or lattices. We present the first practical construction of a round-optimal blind signature in the random oracle model based on standard[…]-
Cryptography
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Cryptanalyse différentielle de chiffrements conjugués.
Speaker : Jules Baudrin - UC Louvain
En cryptographie symétrique, le choix d'une (ou de plusieurs) représentation appropriée est un point crucial à la fois dans la recherche d'attaques et dans la conception de nouvelles primitives. En effet, les transformations mises en oeuvre sont souvent représentées commes des ensembles de polynômes univariés ou multivariés et cette pluralité de points de vue est très féconde. Par exemple, l'AES[…] -
Euclidean lattice and PMNS: arithmetic, redundancy and equality test
Speaker : Fangan Yssouf Dosso - Laboratoire SAS, École des Mines de Saint-Étienne
The Polynomial Modular Number System (PMNS) is an integer number system that aims to speed up arithmetic operations modulo a prime number p. This system is defined by a tuple (p, n, g, r, E), where p, n, g and r are positive integers, and E is a polynomial with integer coefficients, having g as a root modulo p. Arithmetic operations in PMNS rely heavily on Euclidean lattices. Modular reduction in[…] -
Updatable Encryption from Group Actions
Speaker : Maxime Romeas - ANSSI
Updatable Encryption is a variant of symmetric encryption that allows to rotate the encryption key in the outsourced storage setting while minimizing the bandwith used. Indeed, any third party can update ciphertexts to the new key using a token provided by the key holder. UE schemes aim at providing strong confidentiality guarantees against adversaries that can corrupt keys and tokens. In this[…]