Efficient Identity-Based Public Integrity Auditing of Shared Data in Cloud Storage With User Privacy Preserving

Provable Data Possession (PDP) model provides an efficient means for people to audit the integrity of data stored in cloud storage. When sensitive data is shared among multiple users based on cloud storage, it is critical to preserve the anonymity of the data uploader against the auditor. That is, the auditor should not get data uploader's identity through the data audition. To address this problem, many PDP schemes with user identity privacy-persevering are proposed. However, most proposed schemes are designed based on PKI technique which suffers from big burden of certificate management. Moreover, data auditors in most proposed schemes bear heavy computation cost which results to the lower efficiency of the scheme. To overcome the shortcomings, we present a novel identity-based PDP protocol to audit efficiently the integrity of group shared data with uploader's privacy-preserving. Due to the inherent structural advantage of identity-based crypto mechanism, our PDP scheme is able to avoid the problem of certificate management. Different from previous works, our scheme ensures the relationship of the data and the data uploader in the phase of proof generation not the phase of integrity audition. Therefore, the data auditor does not know the relationship at all as well as the extract data uploader of the challenged data. At the same time, establishing the relationship by cloud server in proof generation step can reduce the computational cost of data auditor greatly. Furthermore, the relationship of data uploader and challenged data in the proof is randomized so as to strength the security of the scheme. All these efforts are made in our scheme to efficiently realize the anonymity protection of the data uploader. We give the detailed security proof of our scheme under the computational Diffie-Hellman assumption. Many experiments are performed to evaluate the efficiency of our scheme, the results show that our new scheme is efficient and feasible.