New Constructions and Proof Methods for Large Universe Attribute-Based Encryption

We propose two large universe Attribute-Based Encryption constructions. In a large universe ABE construction any string can be used as an attribute and attributes need not be enumerated at system setup. Our first construction establishes a novel large universe Ciphertext-Policy ABE scheme on prime order bilinear groups, while the second achieves a significant efficiency improvement over the large universe Key-Policy ABE systems of Lewko-Waters and Lewko. Both schemes are selectively secure in the standard model under two “q-type” assumptions similar to ones used in prior works. Our work brings back “program and cancel” techniques to this problem. We provide implementations and benchmarks of our constructions in Charm; a programming environment for rapid prototyping of cryptographic primitives.