Securing Data Stored in Clouds Using Privacy Preserving Authenticated Access Control?

we propose a privacy preserving access control scheme for data storage, which supports anonymous authentication and performs decentralized key management. In the proposed scheme, the cloud adopts an access control policy and attributes hiding strategy to enhance security. This new scheme supports secure and efficient dynamic operation on data blocks, includ-ing: data update, creation, modification and reading data stored in the cloud. Moreover, our authentication and access control scheme is decentralized and robust, unlike other access control schemes designed for clouds which are centralized. We also provide options for file recovery. Extensive security and performance analysis shows that the proposed scheme is highly effi-cient and resilient against replay attacks. User revocation and access control policies highly contributes to avoid abuse of cloud services and shared technology issues.