Analysis of the Internet Key Exchange protocol using the NRL Protocol Analyzer

We show how the NRL Protocol Analyzer, a special-purpose formal methods tool designed for the verification of cryptographic protocols, was used in the analysis of the Internet Key Exchange (IKE) protocol. We describe some of the challenges we faced in analyzing IKE, which specifies a set of closely related subprotocols, and we show how this led to a number of improvements to the Analyzer. We also describe the results of our analysis, which uncovered several ambiguities and omissions in the specification which would have made possible attacks on some implementations that conformed to the letter, if not necessarily the intentions, of the specifications.