Secure and Efficient Cloud-Based Multi-Party Private Set Intersection With Union Protocol

Secure Multi-party Computation (MPC) is a highly active research field, with Private Set Intersection (PSI) being a classic subtopic within it. However, simple intersection computation is insufficient for many real-world scenarios, leading to the development of various PSI variant protocols. In this context, we propose a cloud-based multi-party private set intersection with union protocol, denoted as MPSI-U. This protocol securely computes the intersection of the designated party's set with the union of the sets of all other parties, which can be applied to scenarios such as contact tracing. MPSI-U leverages cloud servers to alleviate the computational burden placed on users, while guaranteeing privacy and security simultaneously for all involved parties with the threshold BGN cryptographic system. Furthermore, a comprehensive formal security analysis of the protocol was conducted under the semi-honest model to prove its resilience against potential security threats. Based on our performance analysis, MPSI-U exhibits favorable characteristics in terms of communication and computation overhead. This enhances the versatility of MPSI-U, rendering it a valuable solution that can be widely applied across various domains and scenarios.