Oruta proposes the first privacy-preserving mechanism for public auditing of shared data stored in the cloud. It exploits ring signatures to compute verification information needed to audit integrity without revealing signer identity. The third party auditor can verify integrity of shared data without retrieving the entire file, while keeping private which user signed each block. Existing methods do not consider privacy for shared data or dynamic groups. Oruta aims to efficiently audit integrity for static groups while preserving identity privacy.