Tag-Based Verifiable Delegated Set Intersection Over Outsourced Private Datasets

Verifiable delegated set intersection over outsourced private datasets (VDPSI) enables two parties to outsource their private datasets and delegate the computation of set intersection to the cloud while being able to check the correctness of the result. In this process, the cloud learns nothing about the datasets and the intersection result. However, the existing VDPSI schemes suffer from three substantial shortcomings that limit their use: i) the whole dataset consists of only one subset, ii) they are designed for the static data, and iii) they cannot support other operations. To resolve these problems, we introduce a novel primitive called tag-based VDPSI (TVDPSI), which is designed for the multi-subset case where each subset is associated with one single tag for data classification. To protect privacy, the data is encrypted before being resided to the cloud. The tag is implicitly hidden in each encrypted element. As a result, the cloud cannot learn which data belongs to the same subset beyond the intersection set. Besides, the cloud cannot calculate the intersection except under the permissions of data owners. To the best of our knowledge, TVDPSI is the first VDPSI scheme supporting dynamic update and count operations. The detailed performance evaluation and simulation show that our protocol is more practical in cloud computing.