Group principals and the formalization of anonymity

Abstract

We introduce the concept of a group principal and present a number of different classes of group principals, including thresholdgroup- principals. These appear to naturally useful concepts for looking at security. We provide an associated epistemic language and logic and use it to reason about anonymity protocols and anonymity services, where protection properties are formulated from the intruder's knowledge of group principals. Using our language, we give an epistemic characterization of anonymity properties. We also present a specification of a simple anonymizing system using our theory.