Comment on “Controlled mutual quantum entity authentication with an untrusted third party”

Abstract

Kang et al. (Quantum Inf Process 17(7):159, 2018) proposed a controlled mutual quantum entity authentication protocol with an untrusted third party. We reexamined its security and further found there is a secure flaw, that is, the untrusted third party Charlie can get the shared key between Alice and Bob without being detected. In addition, we gave a strategy to avoid this secure flaw.