Cryptanalysis and improvement of "Game theoretic security of quantum bit commitment"

Recently, Zhou et al. proposed a quantum bit commitment (QBC) protocol by using Bell states. In this paper, we propose a cryptanalysis strategy for the protocol and demonstrate that the sender can successfully change her commitment without being detected by the recipient with a probability 1-(1/2)(n), where n is the number of rounds in executing the protocol. Hence, the protocol does not meet the binding property which shows its insecurity. In order to overcome the shortcomings, we propose an improved version of the protocol. The analysis illustrates that the improvement meets the security requirements. (C) 2020 Elsevier Inc. All rights reserved.