Epistemic Verification of Anonymity

Abstract

Anonymity is not a trace-based property, therefore traditional model checkers are not directly able to express it and verify it. However, by using epistemic logic (logic of knowledge) to model the protocols, anonymity becomes an easily verifiable epistemic formula. We propose using Dynamic Epistemic Logic to model security protocols and properties, in particular anonymity properties. We have built tool support for DEL verification which reuses state-of-the-art tool support for automata-based verification. We illustrate this approach by analyzing an anonymous broadcast protocol and an electronic voting protocol. By comparison with a process-based analysis of the same protocols, we also discuss the relative (dis)advantages of the process-based and epistemic-based verification methods in general.