Cryptanalysis of Controlled Bidirectional Quantum Secure Direct Communication Network Using Classical XOR Operation and Quantum Entanglement

The multi-user controlled bidirectional quantum secure direct communication network protocol based on classical EXCLUSIVE-OR operation and quantum entanglement is analyzed. It is shown that this protocol has the information leakage problem, that is, one half of the information the users transmit is leaked out unconsciously. Furthermore, it is also weak against the intercept-measure-resend attack and the Controlled-Not operation attack from an outside adversary, and the different initial state attack from the controller.