Ciphertext-Policy Attribute-Based Encryption (CP-ABE) is suitable for data access control on cloud storage systems. In ABE, to revoke users' attributes, it is necessary to make them unable to decrypt ciphertexts. Some CP-ABE schemes for efficient attribute revocation have been proposed. However, they have not been given a formal security proof against a revoked user, that is, whether they satisfy forward secrecy has not been shown or they just do not achieve fine-grained access control of shared data. We propose an attribute revocable attribute-based encryption with the forward secrecy for fine-grained access control of shared data. The proposed scheme can use both “AND” and “OR” policy and is IND-CPA secure under the Decisional Parallel Bilinear Diffie-Hellman Exponent assumption in the standard model.

We consider the problems of access control and encrypted keyword search for cryptographic cloud storage in such a way that they can be implemented for a multiple users setting. Our fine-grained access control aware multi-user secure keyword search approach interdependently harmonizes these two security notions, access control and encrypted keyword search. Owing to the shrinkage of the cloud server's search space to the user's decryptable subset, the proposed scheme both decreases information leakage and is shown to be efficient by the results of our contrastive performance simulation.

In this letter, we introduce a novel keys distribution optimization scheme for CP-ABE based access control. This scheme integrates roles, role hierarchies and objects grouping to accelerate keys distribution, meanwhile the CP-ABE encrypting overhead is reduced by adopting deterministic cryptographic function. Experiments show that our scheme obtains noticeable improvement over the original one, especially when the number of objects is much greater than that of users.