Flexible Cloud-Assisted Multi-Party Private Set Intersection Protocol

The core of traditional multi-party Private Set Intersection (PSI) protocols revolves around enabling the secret computation of intersections among multiple participants' sets, ultimately allowing the intersection output party to obtain the intersection without breaching any information about elements except the intersection. Currently, numerous classical multi-party PSI protocols and their derivatives exist. For the scenario where “There are some participants go offline during the intersection output phase”, we have designed a cloud-assisted flexible multiparty PSI protocol that primarily accomplishes the following two tasks: (1) Base Protocol: Compare with Kolesnikov's multiparty PSI protocol, we use an oblivious key-value store structure to optimize the oblivious programmed pseudorandom function module, giving the protocol a certain advantage in terms of communication overhead. (2) Protocol Branching: We introduce cloud-assisted computation to ensure that when there are any participants go offline mid-process, the protocol can still run normally and accurately output the intersection results for the remaining participants. Performance testing results indicate that the running time of the base protocol is linearly related to the number of participants and the size of the set elements and the number of participants going offline does not significantly impact the running time of the protocol.