| Quantum Secure Direct Communication is a method of secure information transmission using a direct quantum channel without the need for a shared key.Three-party quantum secure direct communication(3P-QSDC)allows two communicating parties to simultaneously transmit secure information to a third party through a quantum channel.Previous 3P-QSDC protocols have required ideal and reliable measurement equipment,which is difficult to achieve under current experimental conditions.However,imperfect measurement equipment can bring security vulnerabilities in 3PQSDC.In order to solve the above problems,this paper proposes a measurement-device-independent three-party quantum secure direct communication protocol(MDI-3P-QSDC)based on polarization and space hyperentangled state.This new scheme has two main aspects of work:On the one hand,we propose the MDI-3P-QSDC protocol.In this protocol,all measurement tasks are delegated to the fourth-party measurement terminal,which may be untrusted or even controlled by an eavesdropper.This protocol can withstand all possible attacks from actual imperfect measurement equipment and is theoretically unconditionally secure.Compared to previous 3P-QSDC protocols,our protocol has higher security under actual experimental conditions,as well as higher channel capacity,allowing both parties to send 2 bits of secure information to the third party in one communication round.On the other hand,we provide a security analysis of the MDI-3P-QSDC protocol.In our protocol,the security of the three rounds of photon transmission process is ensured by three rounds of security detection.Any interception and retransmission behavior by eavesdroppers in the photon transmission process or the untrustworthiness of the fourth party will increase the error rate,and when the error rate exceeds a certain threshold,it will be detected by both parties.Finally,we give the relationship between Quantum Bit Error Rates(QBERs)and communication bit rates. |
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