Using state space exploration and a natural deduction style message derivation engine to verify security protocols

As more resources are added to computer networks, and as more vendors look to the World Wide Web as a viable marketplace, the importance of being able to restrict access and to insure some kind of acceptable behavior even in the presence of malicious adversaries becomes paramount. Many researchers have proposed the use of security protocols to provide these security guarantees. In this paper, we develop a method of verifying these protocols using a special purpose model checker which executes an exhaustive state space search of a protocol model. Our tool also includes a natural deduction style derivation engine which models the capabilities of the adversary trying to attack the protocol. Because our models are necessarily abstractions, we cannot prove a protocol correct. However, our tool is extremely useful as a debugger. We have used our tool to analyze 14 different authentication protocols, and have found the previously reported attacks for them.