An Efficient Protocol for the Private Comparison of Equal Information Based on Four-Particle Entangled W State and Bell Entangled States Swapping

In order to enable two participants to compare the equality of their information without leaking any information about their respective private inputs, an efficient protocol with the assistance of a semi-honest third party is proposed. Different from previous protocols, this protocol based on four-particle entangled W state and Bell Entangled States swapping. One party cannot learn the other's private information. And the third party also cannot learn any information about the private information except the comparing results. Last, the correctness of the protocol is analyzed and for proving the security of the protocol, various kinds of outside attacks and participant attacks are discussed.