Designing Secure Quantum Key Agreement Protocols Against Dishonest Participants

Quantum key agreement (QKA) aims to negotiate a secure and consistent key among several participants. In this paper, we find that a type of QKA protocol is not secure when a participant is dishonest. He can make the honest participants obtain wrong final keys, which may lead to serious consequences. To resist such attacks, we design a defense strategy by introducing a trusted third party. The theoretical analysis results show that our defense strategy not only can detect the dishonest participant’s attacks, but also can identify who is dishonest. Finally we design an optical platform for participants, and show that both our attack and defense strategies are feasible with current technologies.