Refuting security proofs for tripartite key exchange with model checker in planning problem setting

Abstract

We encode a simplified version of the Canetti and Krawczyk (2001) formalism using asynchronous product automata (APA). We then use a model checker tool, simple homomorphism verification tool (SHVT), to perform state-space analysis on our automata in the setting of planning problem. As a case study, we revisit two tripartite key exchange protocols of Hitchcock, Boyd, and Gonzalez Nieto (2004), which carry claimed security proofs in the Canetti and Krawczyk (2001) model. We refute their proofs of security by pointing out previously unpublished flaws in the protocols using SHVT. We then point out corresponding flaws in the refuted proofs