Description
Résumé : Le générateur sac-à-dos, présenté en 1985 est un générateur pseudo aléatoire annoncé sécurisé qui combine un générateur pseudo aléatoire non sécurisé et un problème dur. Une erreur de design repérée en 2011 permet à W. Meier et S. Knellwolf de retrouver une partie du secret mais les explications théoriques et heuristiques sont partielles. Dans cet exposé, je vais présenter une nouvelle attaque contre ce générateur qui exploite la même faiblesse que l'attaque de 2011 mais qui met à jour, de manière beaucoup plus directe, le lien entre le problème à résoudre et les réseaux euclidiens. Grâce à cette meilleure compréhension, la nouvelle attaque retrouve une plus grande partie du secret et sur une plus grande plage de paramètres, pour un coût similaire.
Abstract: The knapsack generator, presented in 1985, is a pseudorandom generator announced as secure, that combines an insecure pseudorandom generator and a hard problem. A design error identified in 2011 allowed W. Meier and S. Knellwolf to recover part of the secret, but the theoretical and heuristic explanations are partial. In this talk, I will present a new attack against this generator that exploits the same weakness as the 2011 attack but that reveals, in a much more direct way, the link between the problem to be solved and Euclidean lattices. Thanks to this better understanding, the new attack recovers a larger part of the secret and on a larger range of parameters, for a similar cost.
Infos pratiques
Prochains exposés
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Verification of Rust Cryptographic Implementations with Aeneas
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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
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