Efficient functional encryption for inner-product values with full-hiding security

Abstract

We construct an efficient non-generic private-key functional encryption (FE) for inner-product values with full-hiding security, where confidentiality is assured not only for encrypted data but also for functions associated with secret keys. Recently, Datta et al. presented such a scheme in PKC 2016 and this is the only scheme that achieved fullhiding security. Our scheme has an advantage over their scheme for the following points. 1. More efficient: our scheme is two times faster in encryption and decryption, and a master secret key, secret keys and ciphertexts are the half size, compared with their scheme. 2. Weaker assumption: our scheme is secure under the decisional linear (DLIN) assumption or its variant, while their scheme is under a stronger assumption, the symmetric external Diffie-Hellman (SXDH) assumption. 3. More flexible: we can apply our scheme to any type of bilinear pairing groups, while their scheme is suitable only for type 3 groups.