Hierarchical Access Structure-based Scheme with Outsourcing and Revocation Mechanism for Cloud Environment

Ciphertext policy attribute-based encryption (CPABE) is one of the efficient implementations of encrypted access control scheme for cloud computing. Though multiple implementations of CPABE exist, there are some issues that need to be addressed, including efficient revocation approach, decryption time, storage cost etc. In this paper, an efficient scheme that incorporates a hierarchical access structure, outsourced decryption, as well as user and attribute revocation is presented. The hierarchical access structure is utilized to encrypt multiple data using one common access structure and makes the encryption process more efficient. The outsourcing server is used to perform partial decryption, so that all heavy computations are performed by this server and less overhead is incurred by the data user. The proposed framework also integrates the evaluation of trustworthiness of data users and service providers to ensure trusted and encrypted access control procedures. The paper also presents an analysis of the time required for performing different operations. Simulation results show that the proposed scheme outperforms the existing approaches.