532 résultats
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Password-Authenticated Key Exchange (PAKE) from Isogenies
Orateur : Sabrina Kunzweiler - Université Bordeaux
The passwords that we use in our everyday life are often chosen to be easily memorable which makes them vulnerable to attacks. This problem is addressed by password-authenticated key exchange (PAKE). The general idea is to enable two parties who share the same (potentially weak) password to establish a strong session key. Most PAKE protocols used today are based on Diffie-Hellman key exchange in[…] -
Finding short integer solutions when the modulus is small
Orateur : Eamonn Postlethwaite - King's College London
We present cryptanalysis of the inhomogenous short integer solution (ISIS) problem for anomalously small moduli by exploiting the geometry of BKZ reduced bases of q-ary lattices. We apply this cryptanalysis to examples from the literature where taking such small moduli has been suggested. A recent work [Espitau–Tibouchi–Wallet–Yu, CRYPTO 2022] suggests small versions of the lattice signature[…] -
How fast do you heal? A taxonomy for post-compromise security in secure-channel establishment.
Orateur : Léo Robert - Université d'Amiens
Post-Compromise Security (PCS) is a property of secure-channel establishment schemes, which limits the security breach of an adversary that has compromised one of the endpoint to a certain number of messages, after which the channel heals. An attractive property, especially in view of Snowden's revelation of mass-surveillance, PCS features in prominent messaging protocols such as Signal. In this[…] -
An extension of Overbeck’s attack with an application to cryptanalysis of Twisted Gabidulin-based schemes.
Orateur : Ilaria Zappatore - XLIM
In this talk, I will discuss the decoding of Gabidulin and related codes from a cryptographic point of view, pointing out that these codes can be decoded solely from the knowledge of a generator matrix. I will also present an extension of Gibson and Overbeck attacks on the generalized GPT encryption scheme (instantiated with the Gabidulin code) for different ranks of the distortion matrix. Finally[…] -
ECDSA White-Box Implementations, Feedback on CHES 2021 WhibOx Contest
Orateur : Agathe Houzelot - Idemia
Cryptographic algorithms are primarily designed to be secure in the black-box model, where an attacker can only observe their input/output behavior. However in practice, algorithms are rarely executed in a completely isolated environment and additional information is often leaked. In the context of mobile applications or connected objects, devices often lack secure storage to protect secret keys,[…] -
Generic Attack on Duplex-Bases AEAD Modes using Random Function Statistics
Orateur : Rachelle Heim Boissier - Inria
Duplex-based authenticated encryption modes with a sufficiently large key length are proven to be secure up to the birthday bound 2^(c/2), where c is the capacity. However this bound is not known to be tight and the complexity of the best known generic attack, which is based on multicollisions, is much larger: it reaches 2^c/α where α represents a small security loss factor. There is thus an[…]