Cloud Computing is related to identity based secure distributed data storage (IBSDDS) schemes. CLOUD computing provides users with a convenient mechanism to manage their personal files with the notion called database-as-a-service (DAS. In DAS schemes, a user can outsource his encrypted files to untrusted proxy servers. Proxy servers can perform some functions on the outsourced ciphertexts without knowing anything about the original files. Data storage systems enable users to store their data to external proxy servers to enhance the access and availability, and reduce the maintainance cost. They addressed the privacy issues in data outsourcing expanding from the data confidentiality to data utility, and pointed out the main research directions in the protection of the externally stored data. The data storage systems comprehensively and classified them into three kinds based on their security services: networked file systems (NFS), storage-based intrusion detection systems (SBIDS) and cryptographic file systems . proxy servers are assumed to be trusted. They authenticate receivers and validate access permissions. The interactions between the proxy servers and receivers are executed in a secure channel. these systems cannot provide an end-to-end data security, namely they cannot ensure the confidentiality of the data stored at the proxy server. In these schemes, a receiver authenticates himself to the proxy server using his password. Then, the proxy server passes the authentication result to the file owner. The owner will make an access permission according to the received information. Query in data storage is executed between a receiver and a proxy server. The proxy server can perform some functions on the outsourced cipher texts and convert them to those for the receiver. As a result, the receiver can obtain the data outsourced by the owner without the proxy server knowing the content of the data