Formalizing provable anonymity in Isabelle/HOL

摘要

We formalize in a theorem prover the notion of provable anonymity. Our formalization relies on inductive definitions of message distinguishing ability and observational equivalence on traces observed by the intruder. Our theory differs from its original proposal and essentially boils down to the inductive definition of distinguishing messages with respect to a knowledge set for the intruder. We build our theory in Isabelle/HOL to achieve a mechanical framework for the analysis of anonymity protocols. Its feasibility is illustrated through two case studies of the Crowds and Onion Routing protocols.