A Collaborative Auditing Blockchain for Trustworthy Data Integrity in Cloud Storage System

Cloud storage system provides data owners with remote storage service, which allows them to outsource data without local storage burden. Nevertheless, the cloud storage service is not fully trustworthy since it may not be honest and remote data would be corrupted. One way to ensure trustworthy preservation of cloud data is the remote data auditing method, through which data owners can check storage reliability of cloud system on demand and avoid potential data corruption in time. However, private auditing methods fail to promise the mutual trust in auditing results. Thus, public auditing methods are introduced, in which traditionally a third party auditor is delegated to interact with cloud service providers for auditing tasks. Although the third party auditor serves as a medium to exchange trust, a centralized third party is hard to stay neutral, which exposes the remote data auditing to some threats such as collusion attacks. To address the trust problem between data owners and cloud service providers, we propose a collaborative auditing blockchain framework for cloud data storage. In this framework, all consensus nodes substitute for the single third party auditor to execute auditing delegations and record them permanently, thereby preventing entities from deceiving each other. Security analysis shows that the proposed framework has advantage of preserving remote data integrity from various attacks. Performance analysis demonstrates that the framework is more functional and resource-friendly than existing schemes.