With the development of Internet, cloud computing has emerged to provide service to data users. But, it is necessary for an auditor\non behalf of users to check the integrity of the data stored in the cloud. The cloud server alsomust ensure the privacy of the data. In\na usual public integrity check scheme, the linear combination of data blocks is needed for verification. But, after times of auditing\non the same data blocks, based on collected linear combinations, the auditor might derive these blocks. Recently, a number of\npublic auditing schemes with privacy-preserving are proposed. With blinded linear combinations of data blocks, the authors of\nthese schemes believed that the auditor cannot derive any information about the data blocks and claimed that their schemes are\nprovably secure in the random oracle model. In this paper, with detailed security analysis of these schemes, we show that these\nschemes are vulnerable to an attack from the malicious cloud server who modifies the data blocks and succeeds in forging proof\ninformation for data integrity check.
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