Fully Secure Online/Offline Predicate and Attribute-Based Encryption

This paper presents the first fully secure online/offline predicate encryption (PE) and attribute-based encryption (ABE) schemes that split the computation required for encryption into two phases: A preparation phase that does the vast majority of the work to encrypt a message before knowing the actual message and the attributes or access control policy that will be used. A second phase can then rapidly assemble a ciphertext when the specifications become known. Our PE schemes support generalized inner-product predicates, while, our ABE scheme supports non-monotone access structures. All the proposed schemes are unbounded in the sense that the size of the public parameters is constant. The security of all the schemes are based on the Decisional Linear assumption. The best part of our constructions is that they exhibit better online performance despite of providing stronger security guarantees compared to the existing work.