627 résultats
-
Efficient Intrusion-Resilient Signatures Without Random Oracle
Orateur : Benoit Libert - Université Catholique de Louvain
Intrusion-resilient signatures are key-evolving protocols that extend the concepts of forward-secure and key-insulated signatures. As in the latter schemes, time is divided into distinct periods where private keys are periodically updated while public keys remain fixed. Private keys are stored in both a user and a base; signature operations are performed by the user while the base is involved in[…] -
Computationally Sound Security Proof using Formal Models
Orateur : Véronique Cortier - LORIA
Since the 1980s, two approaches have been developed for analyzing security protocols. One of the approaches relies on a computational model that considers issues of complexity and probability. This approach captures a strong notion of security, guaranteed against all probabilistic polynomial-time attacks. The other approach relies on a symbolic model of protocol executions in which[…] -
Analyse automatique de protocoles de sécurité
Orateur : Michael Rusinowitch - LORIA
Nous présentons une méthode pour automatiser l'analyse des protocoles cryptographiques à partir de leurs descriptions sous forme de règles d'envoi de messages. Le problème de la détection d'attaque dans un environnement hostile se ramène à la résolution de contraintes sur un espace de messages. La résolution de ces contraintes implantée dans le logiciel issu du projet européen AVISPA est[…] -
Symbolic verification of Diffie-Hellman-based group key exchange
Orateur : Yassine Lakhnech - VERIMAG
We discuss the cryptographic soundness of a symbolic model for Diffie-Hellman based key exchange protocols including symmetric encryption. Our main tool is a new dynamic variation of the decisional Diffie-Hellman problem useful for group protocols. -
An Automatic Security Protocol Verifier based on Resolution
Orateur : Bruno Blanchet - ENS
We present a technique for the verification of cryptographic protocols, based on an abstract representation of the protocol by a set of Horn clauses, and on a resolution algorithm on these clauses. This technique allows a flexible encoding of many cryptographic primitives. It can verify a wide range of security properties of the protocols, such as secrecy, authenticity, and limited cases of[…] -
Theta identities and Thomae formulas
Orateur : Yaacov Kopeliovich
In this talk we apply Thomae formulas to obtain algebraic relations satisfied by Riemann surfaces that are cyclic covers of the Sphere. We focus on the genus 2 case and then give an example of a higher genus case (g=4) that was not known before. The conjectural connection of these identities as well as Thomae formulas to the moduli action of the Braid group is explained.<br/> We present a[…]