Privacy-preserving public auditing for non-manager group

Cloud data privacy-preserving and integrity verification have become major research areas. Many existing schemes use group signatures to make sure that the data stored in cloud is unbroken for the purpose of privacy and anonymity. However, group signatures do not consider user equality and the framing caused by manager. Therefore, we propose data sharing scheme for non-manager groups, which reconstructs democratic group signature with threshold traceability to homomorphic authentication. We further present a public auditing scheme for non-manager shared data. In our scheme, group manager's rights are distributed to all members equally and some of them can work together to trace the signer if it is necessary. Besides identity privacy, data privacy, traceability and non-frameability, our scheme also ensures the efficiency and the feasibility. The experimental results show the overhead of the auditing is independent of the group user numbers and effectiveness of our approach. And thanks to the low overhead, our scheme can be further used in mobile cloud storage.