Where Next for Formal Methods?

In this paper we propose a novel approach to the analysis of security protocols, using the process algebra CSP to model such protocols and verifying security properties using a combination of the FDR model checker and the PVS theorem prover. Although FDR and PVS have enjoyed success individually in this domain, each suffers from its own deficiency: the model checker is subject to state space explosion, but superior in finding attacks in a system with finite states; the theorem prover can reason about systems with massive or infinite states spaces, but requires considerable human direction. Using FDR and PVS together makes for a practical and interesting way to attack problems that would remain out of reach for either tool on its own.