Long-lived authentication protocols for process control systems

Process control systems that manage critical infrastructures have to be available continuously; they may have nodes that once deployed cannot be easily accessed; and they need to be functional over long periods of time. Since the consequences of critical infrastructure disruptions are potentially serious and since critical infrastructures are under threats ranging from extortion to terrorism, it is vital to keep the security services up to current standards over many years of deployment.The mutual authentication of process control system nodes is a fundamental building block of security. This paper describes authentication protocols for use in long-lived process control systems. The protocols address the issue of longevity by defining, as part of the protocol suites, a means for the cryptographic components of the authentication system to be replaced dynamically and securely. The correctness of the component update protocol is established using an extended version of the Burrows, Abadi and Needham (BAN) authentication logic, which incorporates primitives and rules for reasoning about the belief of the ability of cryptographic modules to maintain secrecy.