Automated Verification of Equivalence on Quantum Cryptographic Protocols.

It is recognized that security verification of cryptographic protocols tends to be difficult and in fact, some flaws on protocol designs or security proofs were found after they had been presented. The use of formal methods is a way to deal with such complexity. Especially, process calculi are suitable to describe parallel systems. Bisimilarity, which denotes that two processes behave indistinguishably from the outside, is a key notion in process calculi. However, by-hand verification of bisimilarity is often tedious when the processes have many long branches in their transitions. We developed a software tool to automatically verify bisimulation relation in a quantum process calculus qCCS and applied it to Shor and Preskill’s security proof of BB84. The tool succeeds to verify the equivalence of BB84 and an EDP-based protocol, which are discussed in their proof.