Offline Arbitrated Semi-Quantum Signature Scheme with Four-Particle Cluster State

The emergence of the semi-quantum concept makes it possible for people without quantum capabilities to communicate securely. An offline arbitrated semi-quantum signature scheme based on four-particle cluster states is put forward, in which two classical parties could complete the signature with the assistance of the quantum arbitrator. Different from the typical arbitrated quantum signature schemes, the arbitrator in our protocol acts as a relay station for delivering signature and no longer intervenes in the direct authentication of signature, leaving the signature receiver with full authentication rights. There is no additional direct communication between the signer and the receiver, which reduces the complexity of transmission. Besides, security analysis manifests that the proposed semi-quantum signature scheme is secure.