Simple, Fast Malicious Multiparty Private Set Intersection

We address the problem of multiparty private set intersection against a malicious adversary. First, we show that when one can assume no collusion amongst corrupted parties then there exists an extremely efficient protocol given only symmetric-key primitives. Second, we present a protocol secure against an adversary corrupting any strict subset of the parties. Our protocol is based on the recently introduced primitives: oblivious programmable PRF (OPPRF) and oblivious key-value store (OKVS). Our protocols follow the client-server model where each party is either a client or a server. However, in contrast to previous works where the client has to engage in an expensive interactive cryptographic protocol, our clients need only send a single key to each server and a single message to a pivot party (where message size is in the order of the set size). Our experiments show that the client's load improves by up to 10x (compared to both semi-honest and malicious settings) and that factor increases with the number of parties. We implemented our protocol and conducted an extensive experiment over both LAN and WAN and up to 32 parties with up to $2^20$ items each. We provide a comparison of the performance of our protocol and the state-of-the-art for both the semi-honest setting (by Chandran et al.) and the malicious setting (by Ben Efraim et al. and Garimella et al.).