Association for Computing Machinery
Several distributed file and information systems require complex access-control mechanisms, where access decisions depend upon attributes of the protected data and access policies assigned to users. The authors construct an Attribute-Based Encryption (ABE) scheme that allows a user's private key to be expressed in terms of any access formula over attributes. Previous ABE schemes were limited to expressing only monotonic access structures. They provide a proof of security for their scheme based on the decisional Bilinear Diffie-Hellman (BDH) assumption. Furthermore, the performance of their new scheme compares favorably with existing, less-expressive schemes.