In this paper, the authors focus on cloud secure data storage, which has always been an important aspect of Quality Of Service (QOS). \"Cloud computing may be the only way to handle vast, unstable query loads differentiated data in any number of formats and with any number of relationships\" data Security is considered as major aspect in cloud environment while using an application. This data security can be implemented with respect to user authentication and authorization using cryptography system. Data security involves encrypting the data as well as ensuring that appropriate policies are enforced for data sharing. In this way, data security becomes more and more important in cloud computing.