基于GHZ态的两方量子密钥协商协议

针对目前基于多粒子纠缠态的量子密钥协商协议利用现有技术无法实现多粒子纠缠态的联合测量问题, 本文基于三粒子GHZ态，提出了一个新的两方量子密钥协商协议。该协议通过利用三粒子GHZ态的测量相关性和延迟测量技术，确保了两个参与者能公平地建立一个共享秘密密钥。由于该协议仅用到了Bell测量和单粒子测量，它在现有技术基础上实现较容易。安全性分析证明了此协议既能抵抗参与者攻击和外部攻击，也能成功地抵抗两种特洛伊木马攻击。并且该协议不但在无噪声量子信道上是安全的，而且它在量子噪声信道上也是安全的。最后，与已有的安全两方量子密钥协商协议比较发现该协议也能达到很高的量子比特效率。

Two-party Quantum Key Agreement Protocol Based on GHZ States

In order to solve the problem that the multi-particle joint measurements are difficult to implement with the existing technology in the quantum key agreement protocols based on multi-particle entangled states , a new two-party quantum key agreement protocol was proposed based on three-particle GHZ states. Two participants in the protocol could fairly establish a shared secret key by using the measurement correlation property of three-particle GHZ states and the delayed measurement technique. Since the new protocol only used Bell measurements and single particle measurements, it was easy to achieve on the basis of the existing technology. The security analysis showed that the protocol could not only resist against participant attacks and outsider attacks, but also resist against two kinds of Trojan horse attacks. The protocol was secure not only in the noise-free quantum channel but also in the quantum noise channel. Finally, the comparison with the existed secure two-party protocols showed that the protocol also achieved higher qubit efficiency.