Analysing Time Dependent Security Properties in CSP Using PVS

This paper details an approach to verifying time dependent authentication properties of security protocols. We discuss the introduction of time into the Communicating Sequential Processes (CSP) protocol verification framework of [11]. The embedding of CSP in the theorem prover PVS (Prototype Verification System) is extended to incorporate event-based time, retaining the use of the existing rank function approach to verify such properties. An example analysis is demonstrated using the Wide-Mouthed Frog protocol.