En théorie des codes, la notion de localité est apparue dans le courant des années 1990, dans le contexte des "preuves vérifiables en probabilité" (probabilistically checkable proof, PCP). En particulier, elle consiste a étudier le décodage d'un symbole d'un mot
Chimera is common framework for scale-invariant fully homomorphic schemes based on Ring-LWE, unifying the plaintext space and the noise representation. This hybrid protocol allows to use multiple libraries during the same computation and provides the possibility to take advantage of
Un algorithme efficace retournant tous les espaces vectoriels de dimension d contenus dans un ensemble d'éléments de {0,1}^n a de nombreuses applications en fonctions booléennes et, plus généralement, en cryptographie symétrique. Tout d'abord, je vais présenter les idées derrière un
Recent algorithmic improvements of discrete logarithm computation in special extension fields threaten the security of pairing-friendly curves used in practice. A possible answer to this delicate situation is to propose alternative curves that are immune to these attacks, without compromising
Motivated by the recent applications of isogeny graphs in cryptography, we review topics related to isogenies of elliptic curves defined over finite fields, and their computations. Isogeny graphs come in two families: complex multiplication (CM) and supersingular. CM graphs enjoy
In 2011, Gregor Leander et al. found a new type of attacks against lightweight block ciphers called Invariant attacks. Four years later, this class of attacks has been generalized by Todo and Leander into the nonlinear invariant attacks. It appeared
Le but de l’exposé sera de présenter quelques travaux s’articulant autour de l’utilisation d’objets calculables pour l’étude des variétés algébriques (existence de points réels, discussion de la structure des solutions en fonction de paramètres, connexité, paramétrisation de solutions de systèmes
MDS matrices are essential in symmetric-key cryptography since they provide optimal diffusion in block ciphers. Many MDS matrices are known, but a problem remains which gathers a lot of attention: finding lightweight MDS matrices. Several approaches exist, namely reducing the
The HiMQ-3 signature scheme is a very efficient multivariate signature scheme and was one of the first round candidates of the NIST post-quantum standardization process. In this talk we present a new attack against HiMQ-3, the so called singularity attack.
The generalized birthday problem, or k-xor problem, has many applications in cryptography. Interestingly, there is a gap between its provable query complexity and its best known time complexity, obtained with Wagner’s algorithm. Quantum algorithms for this problem have been studied
