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
-
Verification of Rust Cryptographic Implementations with Aeneas
Orateur : Aymeric Fromherz - Inria
From secure communications to online banking, cryptography is the cornerstone of most modern secure applications. Unfortunately, cryptographic design and implementation is notoriously error-prone, with a long history of design flaws, implementation bugs, and high-profile attacks. To address this issue, several projects proposed the use of formal verification techniques to statically ensure the[…] -
On the average hardness of SIVP for module lattices of fixed rank
Orateur : Radu Toma - Sorbonne Université
In joint work with Koen de Boer, Aurel Page, and Benjamin Wesolowski, we study the hardness of the approximate Shortest Independent Vectors Problem (SIVP) for random module lattices. We use here a natural notion of randomness as defined originally by Siegel through Haar measures. By proving a reduction, we show it is essentially as hard as the problem for arbitrary instances. While this was[…] -
Endomorphisms via Splittings
Orateur : Min-Yi Shen - No Affiliation
One of the fundamental hardness assumptions underlying isogeny-based cryptography is the problem of finding a non-trivial endomorphism of a given supersingular elliptic curve. In this talk, we show that the problem is related to the problem of finding a splitting of a principally polarised superspecial abelian surface. In particular, we provide formal security reductions and a proof-of-concept[…]-
Cryptography
-