A Delegated Offline Private Set Intersection Protocol for Cloud Computing Environments.

Private set intersection (PSI) has a wide range of application scenarios in our daily life like contact matching. With the rise of cloud computing, people hope to use the effective computations and storage capabilities of cloud servers to help complete the PSI computations to reduce their own computing and storage costs. In this paper, we design an efficient PSI protocol based on oblivious transfer (OT), oblivious pseudo-random function (OPRF), and cuckoo filter (CF) for the cloud environments. Our protocol allows clients to upload encrypted private data sets to the cloud server, and the server can act as its agent to perform intersection calculations even when the client is offline. The protocol ensures that the result of the intersection is completely confidential to the server and can only be known by the computing party. Our protocol is efficient and it can be easily extended to multiple parties. A formal detailed security analysis of the protocol is also provided.