A Feasible Quantum Protocol for Private Set Intersection Cardinality

Private Set Intersection Cardinality (PSI-CA) is to compute privately the cardinality of the intersection of two sets, and there are many practical applications of PSI-CA, e.g., data mining and data analysis with the privacy protection. The current classical protocols for PSI-CA could not resist the attacks of quantum computers. In this paper, we present a novel quantum protocol for PSI-CA based on the basic laws of quantum mechanics, which can resist well-known quantum attacks. This protocol utilizes single photons as quantum resources and only needs to apply simple single-photon operators and measurements. Therefore, it is more feasible to implement this protocol, compared with the related quantum protocols, which require entangled states and other complicated operators.