A universal cloud user revocation scheme with key-escrow resistance for ciphertext-policy attribute-based access control

Cloud storage service allows its users to store and share data in a cloud environment. To secure the data from unauthorized entities while sharing, cryptographic mechanisms are used. Ciphertext-Policy Attribute-Based Encryption (CP-ABE) is one such mechanism, which has been widely used to achieve fine-grained access control over encrypted data. However, user revocation and keyescrow, in CP-ABE, are still remaining as challenging problems. In this paper, we propose a key-escrow resistant CP-ABE based access control scheme to provide efficient user revocation. The security analysis of the scheme has been done using Information Theory Tools. The security analysis establishes that it is unconditionally secure and provides any-wise revocation capability. Moreover, comparison with the other notable works in the area shows that it outperforms them in terms of computational and communication overheads.