International Association
for Cryptologic Research

Multi-Authority Attribute-Based Encryption (MA-ABE) is an emerging cryptographic primitive for enforcing fine-grained attribute-based access control on the outsourced data in cloud storage. However, most of the previous multi-authority attribute-based systems are either proven security in a weak model or lack of efficiency in user revocation. In this paper, we propose a novel multi-authority attribute-based data access control system for cloud storage. We construct a new multi-authority CP-ABE scheme with decryption outsourcing. We largely eliminate the decryption overhead for users by outsourcing the undesirable bilinear pairing operations to the cloud servers. The proposed scheme is proven adaptively secure in the standard model and supports any monotone access policy. We also design an efficient attribute-level user revocation approach with less computation cost. The security analysis, numeral comparisons indicate that the proposed system is secure, efficient and scalable.