Formal Verification of Security Protocols

Abstract

AbstractSecurity protocols address the question of how one communicates ‘securely’ in an untrusted ‘hostile’ environment. This chapter introduces the general notions of cryptography, communication protocols, security goals, and security protocols. Taking the Needham-Schroeder authentication protocol as an example, the chapter demonstrates that it is difficult to get the design of security protocols ‘right’. This raises the need for a rigorous approach to analysing security protocols at a design level. To this end, the chapter discusses the Csp approach of modelling security protocols, security properties, and when a protocol satisfies a desired property. It then presents two different approaches for protocol analysis: (1) an automated approach via model checking, where the challenge lies in finding the right coding tricks in order to ‘tame’ state space explosion; and (2) a manual approach using rank functions, where the challenge lies in finding a suitable protocol invariant.