Rohit Chadha , Stéphanie Delaune and Steve Kremer Epistemic Logic for the Applied Pi Calculus Research Report LSV - 09 - 06 March 2009

We propose an epistemic logic for the applied pi calculus, which is a variant of the pi calculus with extensions for modeling cryptographic protocols. In such a calculus, the security guarantees are usually stated as observational equivalence. While process calculi provide a natural means to describe the protocols themselves, epistemic logics are often better suited for expressing certain security properties such as secrecy and anonymity. We intend to bridge the gap between these two approaches: using the set of traces generated by a process as models, we define a logic which has constructs for reasoning about both intruder’s epistemic knowledge and the set of messages in possession of the intruder. As an example we consider two formalizations of privacy in electronic voting and study the relationship between them.