Existing fine-grained and secure access control systems deployed in mobile cloud computing (MCC) typically focus on offloading encryption and/or decryption workloads to the delegated proxy in the cloud server. However, the privacy and authenticity management of outsourced data with flexible and efficient access policy update in MCC is generally overlooked by existing works. In fact, the signcryption feature is generally required in data access control system where the trust between data owner and multiple mobile users is crucial while the policy update management deals with the dynamic handling of user privilege control lifecycle. In this paper, we propose a privacy-preserving access control scheme supporting signcryption and efficient policy update with policy hiding in MCC setting. Essentially, a fully outsourced attribute-based signcryption (ABSC) and policy update method are devised to allows the data owner to offload ABS operation and policy update cost to be executed by the delegated proxy. Finally, we present our experiments to demonstrate that our proposed scheme is computationally more efficient compared to related works.

KEYWORDS: signcryption, encryption, outsourced data, computationally.