Towards a Strand Semantics for Authentication Logic

Abstract

The logic BAN was developed in the late eighties to reason about authenticated key establishment protocols. It uncovered many flaws and properties of protocols, thus generating lots of attention in protocol analysis. BAN itself was also subject of much attention, and work was done examining its properties and limitations, developing extensions and alternatives, and giving it a semantics.More recently, the strand space approach was developed. This approach gave a graph theoretic characterization of the causally possible interactions between local histories (strands) along with a term algebra to express sent and received messages. This model was designed and has been used by its authors for direct application to authentication protocol analysis. However, it has also quickly attracted the attention of many other researchers in the field as useful in connection to related work, such as model checking approaches.Here we discuss the idea of using strand spaces as the model of computation underlying a semantics for BAN-style expressions. This will help to integrate some of the approaches to security protocol analysis and to hopefully provide BAN logics with a clearer, more useful underlying model than they have had to date.