Toward automatic verification of quantum cryptographic protocols
This work addresses a specific bottleneck in verifying quantum cryptographic protocols for researchers in quantum computing and security, representing an incremental advancement over prior methods.
The paper tackled the limitation of existing state-based bisimulations in quantum process algebras by introducing a novel distribution-based bisimulation for quantum processes, enabling verification of more sophisticated security properties, such as proving the BB84 quantum key distribution protocol is sound and asymptotically secure against intercept-resend attacks with an exponentially decreasing gap.
Several quantum process algebras have been proposed and successfully applied in verification of quantum cryptographic protocols. All of the bisimulations proposed so far for quantum processes in these process algebras are state-based, implying that they only compare individual quantum states, but not a combination of them. This paper remedies this problem by introducing a novel notion of distribution-based bisimulation for quantum processes. We further propose an approximate version of this bisimulation that enables us to prove more sophisticated security properties of quantum protocols which cannot be verified using the previous bisimulations. In particular, we prove that the quantum key distribution protocol BB84 is sound and (asymptotically) secure against the intercept-resend attacks by showing that the BB84 protocol, when executed with such an attacker concurrently, is approximately bisimilar to an ideal protocol, whose soundness and security are obviously guaranteed, with at most an exponentially decreasing gap.