Dynamic Data Operation and Secure access control in cloud computing

The many advantages of cloud computing are increasingly attracting individuals and organizations to outsource their data from local to remote cloud servers. However, security and privacy concerns have arisen as obstacles to widespread adoption of clouds by users. While much cloud security research focuses on enforcing standard access control policies typical of centralized systems, such policies often prove inadequate for the highly distributed, heterogeneous, data-diverse, and dynamic computing environment of clouds. In this paper we propose hierarchical attribute-set-based encryption by extending cipher-text-policy attribute-set-based encryption with a hierarchical structure of users. In addition we add dynamic data operation in cloud data. Dynamic operations on outsourced data, including modification, deletion, and append. Analysis shows the proposed scheme is highly efficient and resilient against malicious data modification attack, and malicious data access.