基于多光子纠缠的具有身份认证功能的多方量子安全直接通信

Multi-party quantum secure direct communication protocol with identity authentication based on multi-photon entanglement

多方量子安全直接通信(multi-party quantum secure direct communication,MQSDC)可使多个信息发送方通过量子信道同时向一个信息接收方传递秘密信息,并从理论上保证传递信息的绝对安全性.已有的MQSDC方案均默认所有通信方为合法通信方,这在实际实验条件下难以保证,为窃听者冒充合法通信方窃取信息或扰乱通信提供了可能.本文提出了基于Greenberger-Horne-Zeilinger(GHZ)态的具有身份认证功能的三方量子安全直接通信方案.信息接收方可同时认证两个实际信息发送方的身份,确认身份合法后,再接收其发送的秘密信息,理论上可保证合法通信方身份认证码以及传输信息的安全.本方案使用单光子测量代替GHZ态测量,操作简单且成功率高.本文对方案在实际实验条件下的安全信息容量进行了数值模拟.本方案在未来量子网络领域具有重要的应用.

Multi-party quantum secure direct communication(MQSDC)enables multiple communication parties to simultaneously transmit secret messages to one message receiver through quantum channels.MQSDC plays an important role in promoting the networking and practicality of QSDC and has wide applications in the economy,commerce,and military fields.Existing MQSDC schemes all assume that all the communication parties are legitimate parties,which is difficult to guarantee in practical applications.The lack of the identity authentication for the communication parties would seriously increase the security risk.In this way,it is possible for eavesdroppers to impersonate legitimate communicators to steal message or disrupt communication.In this paper,we propose the first three-party QSDC protocol with identity authentication based on the Greenberger-Horne-Zeilinger(GHZ)state.Before the communication,the message receiver Alice and each of the two legal message senders share a sequence of keys as the legal message sender’s identity code sequence in advance.Alice generates a large number of three-photon GHZ states.Then,Alice distributes two photons of each GHZ state to the practical message senders Bob1 and Bob2,respectively.The parties first check the security of the photon transmission process.Only when the security checking is past,Alice and the practical message senders perform the identity authentication.The identity authentication is based on the quantum secret sharing theory.In detail,Alice,Bob1,and Bob2 select measurement bases according to their identity codes and announce their measurement results through a public channel.Based on the announced measurement results,Alice can simultaneously authenticate the identities of two practical message senders and ensure the security of their identity authentication codes.After the identity authentication,Alice first measures her photons to release the entanglement.Then,the legal message senders can encode their messages on the photons and send the encoded photons back to Alice.By measuring each transmitted photon and comparing the measurement result with its initial quantum state,Alice can finally read out the transmitted messages from two message senders.Our protocol can guarantee the absolute security of each legal message sender’s identity authentication codes and transmitted messages.In theory,each sender can independently send one bit of secret message to Alice.Our protocol replaces the complicated GHZ measurement with the single photon measurement,which can simplify the experimental operation and achieve higher success probability.The security message capacity of the three-party QSDC protocol under practical experimental conditions is numerically simulated.The simulation results indicate that with the initial fidelity of the GHZ state of P1=0.95,and the channel fidelity of 0.98,the maximal communication distance of our protocol can reach about 21.85 km.Moreover,our protocol can also extend to the MQSDC with arbitrary number of practical message senders,and the identity authentication process can be extended to the bidirectional identity authentication.Based on above feature,our protocol has important applications in the future quantum networks field.