An Efficient Integrity Checking Scheme With Full Identity Anonymity for Cloud Data Sharing

Cloud storage services can support data sharing for a group of users. However, the cloud server may lose some of the shared data when attacked. The integrity of stored data is a key issue for cloud storage. However, identity anonymity, an important problem in data integrity, has not been fully investigated yet. Furthermore, the existing schemes of data integrity checking are usually based on public key infrastructure and thus have to perform complex certificate management. In this paper, we propose an efficient integrity checking scheme to achieve full identity anonymity. Additionally, the proposed scheme can reduce the workloads of certificate management and simplify key management. Inspired by the idea of attribute-based signature, we devise a common predicate to manage the identities of legitimate users and disable illegal users from joining the data sharing. By adopting the technique of the monotone span program, the legitimate user can compute the valid authenticators of shared data for all attributes in the common predicate without the need of binding his attribute set to the shared data. Whereupon, the user's identity remains anonymous to all parties in the data sharing because he can share the data and authenticators without revealing his attribute set to other parties. The extensive experimental results demonstrate that the proposed scheme has less computational and communication overhead compared with the existing schemes while achieving full identity anonymity.