A Computational Logic-based approach to security protocols verification, and its application to the Needham-Schroeder Public Key authentication protocol

In this work we present a proof-theoretic approach to the verification of security protocols. Starting from the perspective of open multi-agent systems, where the internal architecture of the individual system’s components may not be completely specified but it is important to infer and prove properties about the overall system behaviour, we propose a general framework where several kinds of verification can be applied. We take a formal approach based on Computational Logic, to tackle verification at two orthogonal levels: ‘static’ verification of protocol properties, and ‘dynamic’ verification of compliance of agent communication. The first one could investigate the possibility that while two agents are correctly following a given protocol a malicious agent can learn secrets exchanged by them. The second one could be about automatically checking that a group of agents interacting with each other are indeed following a given protocol. The main advantages of our approach are (1) from a formal perspective, in the declarative protocol specification language, associated with a rigorous declarative and operational semantics, and (2) from an engineering perspective, in the reduction of the gap between protocol specification, verification and implementation. We study our approach in the domain of security protocols by presenting its application to the well-known Needham-Schroeder Public Key authentication protocol.