Description
Authentication protocols, run between a prover and a verifier, allow the verifier to check the legitimacy of the prover. A legitimate prover should always authenticate (the correctness requirement), while illegitimate parties (adversaries) should not authenticate (the soundness or impersonation resistance requirement). Secure authentication protocols thwart most Man-in-the-Middle (MIM) attacks, such as replays, but they do not prevent relay attacks , where a coalition of two adversaries, a leech and a ghost , forwards messages between an honest verifier and an honest, far-away prover so as to let the illegitimate ghost authenticate.<br/> Distance-bounding protocols strengthen the security of authentication so as to prevent pure relaying, by enabling the verifier to upper-bound his distance to the prover. This is done by adding a number of time-critical challenge-response rounds, where bits are exchanged over a fast channel; the verifier measures the challenge-response roundtrip and compares it to a time-based proximity bound. There are four attacks such protocols should prevent: mafia fraud, where a MIM adversary tries to authenticate in the presence of a far-away (honest) prover, without purely relaying messages (the clock prevents this); terrorist fraud, where the prover is dishonest and helps the MIM adversary authenticate insofar as this help does not give the adversary any advantage for future (unaided) authentication; distance fraud, where a far-away prover wants to prove he is within the verifier's proximity; and (lazy-round) impersonation security, requiring a degree of impersonation security even for the exchanges that are not timed. Constructing distance-bounding protocols is a highly non-trivial task, since often providing security against one requirement creates a vulnerability with respect to a different requirement. I propose to describe how to construct distance-bounding protocols which are probably secure and also guarantee the prover's privacy.
Next sessions
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Module Learning With Errors and Structured Extrapolated Dihedral Cosets
Speaker : Jinwei Zheng - Télécom Paris
The Module Learning With Errors (MLWE) problem is the fundamental hardness assumption underlying the key encapsulation and signature schemes ML-KEM and ML-DSA, which have been selected by NIST for post-quantum cryptography standardization. Understanding its quantum hardness is crucial for assessing the security of these standardized schemes. Inspired by the equivalence between LWE and[…]-
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[…] -
Journée post-quantique du séminaire cryptographie
Journée scientifique sur la cryptographie post-quantique dans la foulée de l'European Cyber Week avec des exposés plus techniques que ceux de l'ECW.