A Hidden Vector Encryption Scheme with Constant-Size Tokens and Pairing Computations

The Hidden Vector Encryption scheme is one of the searchable public key encryption schemes that allow for searching encrypted data. The Hidden Vector Encryption scheme supports conjunctive equality, comparison, and subset queries, as well as arbitrary conjunctive combinations of these queries. In a Hidden Vector Encryption scheme, a receiver generates a token for a vector of searchable components and sends the token to a query server which has the capability to evaluate it on encrypted data. All of the existing Hidden Vector Encryption schemes, which are all pairing-based, require token elements and pairing computations proportional to the number of searchable components in the token. In this paper, we suggest an improved paring-based Hidden Vector Encryption scheme where the token elements and pairing computations are independent of the number of searchable components. Namely, for an arbitrary conjunctive search query, the token is of size O(1) and the query server only needs O(1) pairing computations. The latter improvement in particular might be very attractive to a query server in a larger search system with many users. To achieve our goal, we introduce a novel technique to generate a token, which may be of independent interest.