Three-Party Semi-Quantum Key Agreement Protocol

A semi-quantum key agreement protocol is proposed to allow one quantum participant and two classical ones to negotiate the final shared secret key equally. The protocol employs the four-particle cluster state, whose large persistency of entanglement could ensure the feasibility and the security of the protocol. The security of the proposed semi-quantum key agreement protocol against various attacks including the external eavesdropper’s attacks and the participant’s attacks is discussed. Furthermore, in comparison with the previous quantum key agreement and semi-quantum key agreement protocols, the proposed semi-quantum key agreement protocol contains more classical parties, requires less quantum channels, and needs no external assistance.