Quantum Private Comparison Based on Delegating Quantum Computation

Based on delegating quantum computation (DQC) model, a two-party quantum private comparison protocol with single photons is proposed, and it is also generalized to the multi-party case. In the protocols, the clients' inputs are firstly encrypted with the shared keys, and then sent to quantum center (QC) to perform quantum computation, i.e., the CNOT operations with which QC can get the comparison result. By utilizing the DQC model, clients with limited quantum resources can delegate semi-honest QC to perform quantum comparison of equality, besides their information sequences are encrypted and transmitted only once. Analysis shows that out protocols have very good security, low communication complexity and high efficiency.