Semi-quantum Key Agreement Protocol against Dishonest Third-party with Delegating Quantum Measuring

Abstract

Abstract In quantum cloud environment, most application protocols have the problems of using a lot of quantum resources, high communication costs, and inability to check the honesty of cloud server. Therefore, a semi-quantum key agreement protocol based on GHZ-like state with a dishonest delegated measuring center is proposed. In our protocol, the application system consists of a quantum cloud server which only needs to prepare GHZ-like states and distributes all the particles to other participants, a quantum measuring center which performs complicated quantum measurement, such as X-base measurement and Bell measurement, and many classical semi-quantum participants which perform key agreement. Our protocol has many advantages. First, our protocol removes the assumption of honest or semi-honest cloud server because the dishonesty of cloud sever can be checked by delegated measuring center and classical semi-quantum participants. Second, the dishonesty of measuring center can also be found by classical semi-quantum participants through joint measurement. Third, only classical semi-quantum participants can obtain random shared key even if quantum cloud server and measuring center are interested in shared keys. Fourth, a large number of participants may be semi-quantum users which saving a lot of quantum resources. Our protocol is especially suitable for applications such as a large number of classical users arbitrarily performing key agreement in a real cloud environment which only need fewer resources, being easy to implement, and controllable. Security analysis and efficiency analysis show that our protocol can not only effectively resist external and internal attacks, but also resist collusion attack, which is more efficient than similar protocols.