Improved Verifiable Delegated Private Set Intersection

Verifiable delegated private set intersection, VD-PSI, is a kind of secure function evaluation protocol to compute the set intersection between clients datasets which are stored in the cloud in encrypted form without leaking any information. In VD-PSI, clients can verify validity of the computation result returned from the cloud. At FC 2016, Abadi et al. proposed a VD-PSI scheme based on a homomorphic encryption. However, their scheme has several problems in a practical sense; First, their scheme requires that clients must establish a secure channel between them in advance. Next, costs for clients are not fair because computational and communication costs for a client are much heavier than the peer. In this paper, we introduce an improved VD-PSI scheme. Our scheme has two main advantages: First, no secure channel is required even between clients; and thus, clients do not need to negotiate with each other in advance. The other advantage is ef fi ciency and complexity fairness of clients because communication costs for clients are balanced, and total costs for clients are about 62% of the previous scheme.