Semi-Quantum Key Agreement and Private Comparison Protocols Using Bell States

Semi-quantum protocol uses fewer resources and more flexible, which can still guarantee the unconditional safety. Based on Bell states, this paper first presents a semi-quantum key agreement protocol which allows two classical parties (Alice and Bob) to negotiate a shared secret key with the help of a quantum party (server). Classical parties only can perform reflection operation and measurement the qubit in the classical basis {|0〉, |1〉} in the protocol. During the protocol execution, Alice and Bob equally contribute in determining the final key and no one can manipulate and know the key prior to the other one. The security of the proposed protocol has been discussed, which analysis results show that the proposed protocol not only guarantees the security of the shared secret key but also assures the fairness property. We also analyze the efficiency of the proposed protocol. In addition, a semi-quantum private comparison protocol is proposed based on the key agreement protocol.