Description
In November 2004, the European Network of Excellence for Cryptology (ECRYPT) launched a call for new stream cipher primitives. Authors from academia as well as industry submitted 34 designs, and in May 2008, 8 ciphers were chosen for the eSTREAM final portfolio. In this talk, we look back at the history of stream ciphers to understand the design choices made by cryptographers today. We start by reviewing "historical" designs based on linear feedback shift registers, such as the GSM A5/1 cipher. We explain basic cryptanalytic techniques - such as guess-and-determine attacks and correlation attacks - used to break LFSR-based ciphers. We also stop briefly to examine the importance of state size and key/IV length w.r.t. time-memory trade-offs. We then move on to the beginning of 2000s, which brought us new designs from the NESSIE research project, including SNOW 2.0, later to become the 3G mobile standard SNOW 3G. We discuss how new cryptanalytic tools, most notably algebraic cryptanalysis, reshaped design principles in modern ciphers, and review some of the eSTREAM submissions.<br/> In the second part of this talk, we focus on the cryptanalysis of one of the eSTREAM finalists, Moustique. We give a step-by-step overview of our attack that allows to recover the full 96-bit key in 2^{38} steps, using related keys, and allows to speed up exhaustive search in the standard case (without related keys) by a factor 28. Here, we invite the audience to interact, identify weaknesses that lead to the break and propose tweaks to thwart the attack. Cryptanalysis of Moustique is joint work with Vincent Rijmen, Tor E. Bjorstad, Christian Rechberger, Matt Robshaw and Gautham Sekar.
Prochains exposés
-
Adelic reduction of module lattices
Orateur : Henry Bambury - DGA-MI et Inria Rennes
We give a strict generalisation of the LLL algorithm over number fields, based on the reduction theory of $GL(n)$ over the adele ring of a number field. Our algorithm is free of heuristics, with rigorous bounds on output quality and complexity. -- based on joint work with Seungki Kim, Changmin Lee and Phong Nguyen ---
Cryptography
-
-
European Cyber Week: atelier cryptographie post-quantique
Dans la continuité des éditions 2021, 2022 et 2024, la DGA — en partenariat avec CREACH LABS et avec le soutien de l'ANSSI, de l'IRISA, de l'IRMAR et du Pôle d'Excellence Cyber — organise la 4e édition de l'atelier consacré à la cryptographie post-quantique dans le cadre de l'European Cyber Week 2026. Attention, il faut s'inscrire (gratuitement) au préalable — s'inscrire à la conférence Les[…] -
Post-quantum day of the cryptography seminar
A scientific day devoted to post-quantum cryptography, held in the wake of the European Cyber Week, with talks more technical than those presented at the ECW.