Quantum secure direct communication scheme with identity authentication
Authors: Zhou Xian-Tao , Jiang Ying-Hua ,   School of Information Engineering, Xizang Minzu University, Xianyang 712000, China
Published: October 2022

Aiming at the problem that traditional quantum secure direct communication schemes need to assume the legitimacy of both parties in advance, a GHZ state (a quantum state involving at least three subsystems or particles entanglement) based quantum secure direct communication scheme with identity authentication is proposed. The scheme first encodes GHZ state particles into eight types, divides the particles into three parts, and sends them three times. Each time, eavesdropping is added to detect whether the particle detection channel is secure, and identity authentication is added when sending particles for the second time to verify the identity of the receiver. Specifically, according to the value of the ID key IDA, the specified particles (such as <inline-formula><tex-math id="Z-20230114055019-1">\begin{document}$ |0\rangle $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20221684_Z-20230114055019-1.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20221684_Z-20230114055019-1.png"/></alternatives></inline-formula> particles or <inline-formula><tex-math id="Z-20230114055019-2">\begin{document}$ |+ \rangle $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20221684_Z-20230114055019-2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20221684_Z-20230114055019-2.png"/></alternatives></inline-formula> particles) are found in the two particles. Then their positions are marked as <i>L</i> and they traverse down until all the identity keys are traversed, obtaining a position sequence <i>L</i>. After sending the two particles to Bob for eavesdropping detection, Bob measures the <i>L</i> position of the two particles on the corresponding basis according to the value of the identity key, the measurement results are coded, and compared with the identity key IDA to complete the identity authentication. After sending the particles for the third time. the receiver extracts all the detected particles, and then the GHZ state particles are jointly measured, and the original information is recovered through the previously given coding rules, so as to realize quantum safe direct communication. The design of this scheme is simple and efficient, and the communication can be realized without complex unitary transformation. The correctness analysis proves that the scheme is correct in theory. The security analyses of interception/measurement retransmission attack, Trojan horse attack, denial of service attack, auxiliary particle attack, identity impersonation attack, and other attacks prove that the scheme can resist common internal attacks and external attacks, and solve the problem of information leakage. The transmission efficiency of the scheme is 1, the quantum bit utilization is 1, and the coding capacity is a quantum state carrying 3 bits of information. Compared with some previous schemes, this scheme has obvious advantages in these three aspects. The biggest advantage is that the sender does not need to assume the legitimacy of the receiver when sending information, so it has high practical application value.