Description
Since the 1980s, two approaches have been developed for analyzing security protocols. One of the approaches relies on a computational model that considers issues of complexity and probability. This approach captures a strong notion of security, guaranteed against all probabilistic polynomial-time attacks. The other approach relies on a symbolic model of protocol executions in which cryptographic primitives are treated as black boxes. Since the seminal work of Dolev and Yao, it has been realized that this latter approach enables significantly simpler and often automated proofs. However, the guarantees that it offers have been quite unclear.<br/> We present two results that show soundness of formal models with respect to computational notions of security.<br/> First, we establish that symbolic integrity and secrecy proofs are sound with respect to the computational model in the case of protocols that use signatures and asymmetric encryption. This is a join work with Bogdan Warinschi. Secondly, we study the link between formal and cryptographic models for security protocols in the presence of a passive adversary, for abitrary equational theories. We define a framework for comparing a cryptographic implementation and its idealization w.r.t. various security notions. In particular, we concentrate on the computationnal soundness of static equivalence, a standard tool in cryptographic $\pi$-calculi. This is a join work with Mathieu Baudet and Steve Kremer.
Prochains exposés
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Algorithms for post-quantum commutative group actions
Orateur : Marc Houben - Inria Bordeaux
At the historical foundation of isogeny-based cryptography lies a scheme known as CRS; a key exchange protocol based on class group actions on elliptic curves. Along with more efficient variants, such as CSIDH, this framework has emerged as a powerful building block for the construction of advanced post-quantum cryptographic primitives. Unfortunately, all protocols in this line of work are[…] -
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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