Privacy-Preserving Mixed Set Operations

Privacy-preserving set operations have important practical and theoretical significance and have always been a research focus of secure multiparty computation. Most existing studies focus on single set operations which cannot express many complicated set operations. However, the studies on mixed set operations are highly limited. The available protocols for mixed set operations can only be implemented through a threshold fully homomorphic encryption scheme. Since mixed set operations are necessary in practice, it is necessary to design an efficient and practical secure computation protocol for mixed set operations. In this paper, we propose a new protocol for mixed set operations that is based on a new encoding method and the threshold ElGamal cryptosystem. Through an efficiency analysis, it is proved that the efficiency of the protocol that is proposed in this paper are significantly higher than those of the available protocols.