Extended File Hierarchy Access Control Scheme with Attribute-Based Encryption in Cloud Computing

In cloud computing, attribute based encryption (ABE) is often used to solve the challenging issue in secure data storage. In order to lighten the burden of authority center, hierarchical ABE schemes is a very effective way. File hierarchy attribute based encryption (FH-CP-ABE) is a scheme, which both saves storage space of ciphertext and reduces the computation overhead of encryption. However, it's impossible to encrypt multiple files on the same access level in existing FH-CP-ABE scheme. The scheme is obviously not practical. In this paper, an efficient extended file hierarchy CP-ABE scheme (EFH-CP-ABE) is proposed, which can encrypt multiple files on the same access level. Our scheme is very practical especially for those big institutions or companies which have many hierarchical sectors, since it greatly saves storage space and computation cost for them on the cloud servers. Furthermore, our solution also achieves secure and flexible access control for users in cloud storage. We formally prove the security for our new scheme under the standard model. Finally, we implement the corresponding experiment for EFH-CP-ABE scheme and achieve desirable experimental results.