cwPSU: Efficient Unbalanced Private Set Union via Constant-weight Codes
Qingwen Li
Network and Distributed System Security (NDSS) Symposium 2026 · Day 1 · Applied Cryptography
This talk presents **cwPSU**, a novel protocol for **unbalanced Private Set Union (PSU)** that achieves dramatic efficiency improvements over prior work by leveraging **constant-weight encoding**. Private Set Union allows two parties to compute the union of their private datasets without revealing anything beyond the final result. While most existing PSU protocols are designed for balanced scenarios where both sets are roughly the same size, real-world applications frequently involve highly unbalanced settings -- one party's dataset may be orders of magnitude larger than the other's.
AI review
A pure applied cryptography paper optimizing unbalanced Private Set Union via constant-weight encoding and polynomial reformulation. The 13.3x computation and 32.4x communication improvements over prior PSU protocols are technically meaningful within the MPC community, but this has zero relevance to offensive security, vulnerability research, or practical exploitation.