This document proposes a mechanism called Oruta that allows a third party auditor to verify the integrity of shared data stored in the cloud while preserving the privacy of the identities of users. Oruta uses ring signatures to compute verification information for shared data blocks in a way that hides the identity of the signer from the auditor. It allows the auditor to detect any corrupted blocks without retrieving the entire file. This protects user privacy during public audits of shared data stored in the cloud.