Description
The security of modern cryptosystems relies on computational assumptions, which may be challenged by the advent of large-scale quantum computing devices.<br/> While Shor's algorithm is known to break today's most popular public-key schemes, secret-key cryptosystems are generally expected to retain half of their pre-quantum bits of security. However, the precise advantage of quantum attacks cannot be determined without a dedicated analysis.<br/> In this talk, we will focus on key-recovery attacks against block ciphers. These attacks are often categorized in two scenarios, depending on the type of black-box access allowed to the adversary: either a classical query access, or a "quantum" query access where the black-box is part of the adversary's quantum algorithm. Attacks with classical queries, which are deemed more realistic, have so far complied with the rule of halving security levels.<br/> On the contrary, attacks with quantum queries can break some classically secure designs which exhibit a strong algebraic structure (Kuwakado & Morii, ISIT 2010).<br/> Exploiting this structure with classical queries only was the goal of the offline-Simon algorithm of Bonnetain et al. (ASIACRYPT 2019). In the final part of this talk, we will show that this algorithm allows to reach a more than quadratic speedup against some specific block cipher constructions. This is joint work with Xavier Bonnetain and Ferdinand Sibleyras.<br/> lien: https://univ-rennes1-fr.zoom.us/j/97066341266?pwd=RUthOFV5cm1uT0ZCQVh6QUcrb1drQT09
Prochains exposés
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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
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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.