Abstract: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.