Batch Auditing for Multiclient Data in Multicloud Storage

Cloud storage enables users to outsource their data to cloud servers and enjoy the on-demand high-quality services. However, this new paradigm also introduces many challenges due to the security and integrity threats toward user' outsourced data. Recently, various remote integrity auditing methods have been proposed, but most of them can only serve for the single cloud environ- ment or the individual auditing for each data file. In this paper, we develop an efficient auditing mechanism, which support batch auditing for multiple data files in multi-cloud environment. By utilizing the bilinear map, the proposed protocol achieves full stateless and transparent verification. By constructing a sequence-enforced Merkle Hash Tree, the proposed protocol can resist the re- place attack. In addition, our protocol protects the position information of the data blocks by generating fake data blocks to confuse the organizer. By compu- ting intermediate values of the verification on cloud servers, our method can greatly reduce the computing overhead of the auditor. The performance analysis proves the good efficiency of the proposed protocol.