Cloud computing refers to the use and access of multiple server-based computational resources via a digital network (WAN, Internet connection using the World Wide Web, etc.). Cloud users may access the server resources using a computer or other device. In cloud computing, applications are provided and managed by the cloud server and data is also stored remotely in the cloud configuration. Users do not download and install applications on their own device or computer; all processing and storage

more »

... s maintained by the cloud server. Security is the major problem in Cloud as its open to many users. In order to maintain the integrity of data in cloud I am providing public audit ability to the network. This can be done by third party auditor (TPA) on behalf of the cloud client to verify the integrity of the dynamic data stored in the cloud. This will eliminates the interference of Client to check their intactness which can be important in achieving economies of scale for Cloud Computing. The forms of data operation such as block modification, insertion, and deletion is also a significant in the cloud function which will be done here. I detect the security problems of direct extensions with dynamic data updates from prior works and then show how to construct an elegant verification scheme for the seamless integration of these two salient features in my protocol design. In particular, to achieve efficient data dynamics, I improve the existing proof of storage models by manipulating the classic Merkle Hash Tree construction for block tag authentication. To support efficient handling of multiple auditing tasks, I further explore the technique of bilinear aggregate signature to extend my main result into a multiuser setting, where TPA can perform multiple auditing tasks simultaneously. Extensive security and performance analysis show that the proposed schemes are highly efficient and provably secure