Quantum Private Comparison Protocol Based on Four-Particle GHZ States

A new quantum private comparison protocol with four-particle GHZ states is proposed. Unlike most previous quantum private comparison protocols, this quantum private comparison protocol can compare the equality of three information bits in each comparison, which could greatly reduce the times of comparisons. The private input of either party will not be leaked out to others, including participants. Besides, it's simple to implement the protocol with current technologies since only single-particle measurements and Bell measurements are involved. Furthermore, our protocol has good performance of withstanding various outside attacks and participant attacks.