Blockchain-based public auditing for big data in cloud storage

Cloud storage enables applications to efficiently manage their remote data but facing the risk of being tampered with. This paper utilizes blockchain technique to develop a novel public auditing scheme for verifying data integrity in cloud storage. In the proposed scheme, different from the existing works that involve three participatory entities, only two predefined entities (i.e. data owner and cloud service provider) who may not trust each other are involved, and the third party auditor for data auditing is removed. Specifically, data owners store the lightweight verification tags on the blockchain and generate a proof by constructing the Merkle Hash Tree using the hashtags to reduce the overhead of computation and communication for integrity verification. Besides, this work is able to achieve 100% confidence of auditing theoretically, as the hashtag of each data block is utilized to build the Merkle Hash Tree for the data integrity verification. Security analysis shows that the proposed scheme can defend against malicious entities and the 51% attack. Experimental results demonstrate the significant improvements on computation and communication.