Updating Policies in CP-ABE-Based Access Control: An Optimized and Secure Service

Policy update management is one of the key problems in the ciphertext policy-attribute-based encryption (CP-ABE) supporting access control in data outsourcing scenario. The problem is that the policy is tightly coupled with the encryption itself. Hence, if the policy is updated, the data owner needs to re-encrypt files and sends them back to the cloud. This incurs overheads including computation, communication, and maintenance cost at data owner side. The computation and communication overheads are even more costly if there are frequent changes of access control elements such as users, attributes and access rules. In this paper, we extend the capability of our access control scheme: C-CP-ARBE to be capable to support secure and flexible policy updating in data outsourcing environment. We propose a policy updating method and exploit a very lightweight proxy re-encryption (VL-PRE) technique to enable policies to be dynamically and effectively updated in the cloud. Finally, we demonstrate the efficiency and performance of our proposed scheme through our evaluation and implementation.