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Séminaire SSL par Ralf Sasse

28 November 2019 @ 13:30 pm - 14:30 pm

Le prochain exposé du séminaire SSL aura lieu jeudi 28 novembre à 13h30, salle A008. L’orateur sera Ralf Sasse, de l’ETH Zurich.


Title: Seems Legit: Automated Analysis of Subtle Attacks on Protocols that Use Signatures (joint work with Dennis Jackson, Cas Cremers, Katriel Cohn-Gordon)



The standard definition of security for digital signatures — existential unforgeability — does not ensure certain properties that protocol designers might expect. For example, in many modern signature schemes, one signature may verify against multiple distinct public keys. It is left to protocol designers to ensure that the absence of these properties does not lead to attacks.

Modern automated protocol analysis tools are able to provably exclude large classes of attacks on complex real-world protocols such as TLS 1.3 and 5G. However, their abstraction of signatures (implicitly) assumes much more than existential unforgeability, thereby missing several classes of practical attacks.

We give a hierarchy of new formal models for signature schemes that captures these subtleties, and thereby allows us to analyse (often unexpected) behaviours of real-world protocols that were previously out of reach of symbolic analysis. We implement our models in the Tamarin Prover, yielding the first way to perform these analyses automatically, and validate them on several case studies. In the process, we find new attacks on
DRKey and SOAP’s WS-Security, both protocols which were previously proven secure in traditional symbolic models.


La suite du programme sera prochainement annoncée, et sera également disponible en ligne au fur et à mesure sur seminaire-securite.loria.fr.



28 November 2019
13:30 pm - 14:30 pm
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