Tradeoffs are an important part of engineering security. Protocol security is important. So are efficiency and cost. This paper provides an early framework for handling such aspects in a uniform way based on combinatorial optimisation techniques. BAN logic is viewed as both a specification and proof system and as a `protocol programming language'. The paper shows how evolutionary search in the form of genetic algorithms can be utilised to `grow' correct and efficient BAN protocols and shows how goals and assumptions can co-evolve, effectively engaging in `specification synthesis'.
John A. Clark, Jeremy L. Jacob