Controlled quantum secure direct communication with twice identity authentications based on the entanglement swapping of Bell states

Abstract In this paper, after quantum identity authentication is applied into controlled quantum secure direct communication (CQSDC), a CQSDC protocol with twice identity authentications is put forward based on the entanglement swapping of Bell states. In this protocol, firstly, the user Alice and the user Bob respectively utilize decoy single particles to accomplish the identity authentications with the semi-honest control center Charlie; then, Alice and Bob utilize the entanglement swapping of Bell states to finish the identity authentication between them; and finally, Alice utilizes the entanglement swapping of Bell states to transmit her secret message directly to Bob. This protocol is validated to be able to resist the internal attacks from Charlie and the outside attacks from Eve. The correctness of this protocol is proven by the quantum circuit simulations on IBM Qiskit quantum cloud platform.