Semi-quantum key agreement based on maximally three-qubit entangled states

In this paper, a semi-quantum key agreement (SQKA) protocol based on the three-particle maximally entangled GHZ state is proposed. In this SQKA protocol, the classical parties Alice and Bob can only operate the qubits with classical basis, while the quantum party Charlie has full manipulation on qubits. By introducing semi-quantum approach, the requirement for device is reduced. Moreover, each of parties has equal contribution to key formation. The protocol can effectively resist outsider attacks even participant attacks. Through the efficiency analysis, our protocol has a higher qubit efficiency than the previous semi-quantum key agreement.