Privacy Protection Based on Special Identifiers of Intersection Base Computing Technology

Private Set Intersection Cardinality (PSI-CA) and Private Set Union Cardinality (PSU-CA) are two cryptographic primitives whereby two or more parties are able to obtain the cardinalities of the intersection and the union of their respective private sets, and the privacy of their sets is preserved. In this paper, we propose a new privacy protection intersection cardinality protocol, which can quickly deal with set inequality and asymmetry problems and can obtain 100% correct results, and, in terms of efficiency, we are much faster than using the polynomial method. Our protocol adopts the Paillier addition homomorphic encryption scheme and applies the identifier guidance technology, using identifier determination, to the semi-homomorphic encryption ciphertext environment, excluding a large number of different options and quickly finding the base of the intersection of two sides.