Data Storage Security in Cloud Computing

Cloud computing is an emerging computing model in which resources of the computing communications are provided as services over the Internet. This paper proposed some services for data security and access control when users outsource sensitive data for sharing on cloud servers. This paper addresses this challenging open issue by, on one hand, defining and enforcing access policies based on data attributes, and, on the other hand, allowing the data owner to assign most of the computation tasks involved in fine grained data access control to un-trusted cloud servers without disclosing the underlying data contents. Extensive analysis shows that our proposed scheme is highly efficient and provably secures under existing security models. In Order to address this new problem and further achieve a secure and dependable cloud storage service, we propose in this paper a flexible distributed storage integrity auditing mechanism, utilizing the homomorphic token and distributed coded data. By third party auditing in this system, improves the availability and reliability of users data. This paper effectively supports dynamic data operations. As system is distributed, it is very essential to locate the misbehaving server so as that the user can access his sensitive information without any changes in it. This system also works against server attack and data crashes effectively.