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A cloud computing is become more popular as it provides guaranteed services like infrastructure management, online data storage and backup solutions, Web-based e-mail services, database processing, managed technical support services, virtualized infrastructure etc. By using the cloud services, the user can access data stored in a cloud anytime and at anywhere using any device and ensure about less capital investment. To provide promised always on 24/7 access, the cloud service provider (CSP) stores data replicas on multiple geographically distributed servers. It is necessary to compute signatures on the blocks in shared data for users in a particular group, so the shared data integrity can be confirmed publicly. Various blocks in shared data are usually signed by various vast numbers of users due to data alterations performed by different users. Specifically, by utilizing direct anonymous attestation, which is adopted by the Trusted Computing Group as the anonymous method for remote authentication in trusted platform module, users are able to preserve their identity privacy on shared data from a public verifier. The difficulty with this approach is that it requires all the users using designed hardware and needs the cloud provider to move all the existing cloud services to the trusted computing environment, which would be costly and impractical. This paper has made a survey on various privacy preserving techniques in cloud. Here Homomorphic Authenticable Ring Signature (HARS), privacy-preserving public auditing System for data storage security are discussed.