Predicate Private Set Intersection with Linear Complexity.

Private Set Intersection (PSI) enables two parties to learn the intersection of their input sets without exposing other items that are not within the intersection. However, real-world applications often require more complex computations than just obtaining the intersection. In this paper, we consider the setting where each item in the input set has an associated payload, and the desired output is a subset of the intersection obtained by evaluating certain conditions over the payload. We call this new primitive Predicate Private Set Intersection (PPSI) and show its applicability in many different scenarios. While a PPSI protocol can be obtained by combining existing circuit-PSI and generic circuit-based secure computation, this naive approach is not efficient. Therefore, we also provide a specially designed PPSI protocol with linear complexity and good concrete efficiency. We implemented the protocol and evaluated it with extensive experiments. The results validated the efficacy of our PPSI protocol.