Description
Designing secure protocols based on passwords is a difficult task. Indeed, passwords, and more generally low-entropy secrets, are potentially vulnerable to guessing attacks, that is, exhaustive, "brute force" searches. Preventing guessing attacks typically requires a protocol to conceal any partial information on the password (e.g. its checksum) which could help the attacker confirm his guess during the searching process.<br/> Ensuring such a property is not obvious. Based on the seminal work of Lowe, several models and automatic tools have been proposed to analyze protocols with respect to guessing attacks. Unfortunately, these works rely on different symbolic models for which no computational justifications exist so far. (That is, a protocol may be secure in a symbolic model, and yet a feasible attack exists.) In this talk, we will study a recent, symbolic definition of security against guessing attacks, based on static equivalence. First, we will present a decision procedure for a large class of protocols, for a finite number of sessions. Then, we will provide a computational justification in the case of a passive adversary, that is, a pure eavesdropper. [This part is a joint work with M. Abadi and B. Warinschi.]
Next sessions
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Polytopes in the Fiat-Shamir with Aborts Paradigm
Speaker : Hugo Beguinet - ENS Paris / Thales
The Fiat-Shamir with Aborts paradigm (FSwA) uses rejection sampling to remove a secret’s dependency on a given source distribution. Recent results revealed that unlike the uniform distribution in the hypercube, both the continuous Gaussian and the uniform distribution within the hypersphere minimise the rejection rate and the size of the proof of knowledge. However, in practice both these[…]-
Cryptography
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Asymmetric primitive
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Mode and protocol
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Post-quantum Group-based Cryptography
Speaker : Delaram Kahrobaei - The City University of New York