Cooperative provable data possession scheme for multicloud storage

This paper presents a method to correct a flaw in a cooperative provable data possession scheme for multicloud storage that allows clients to verify that the cloud service provider properly stored the client's data. The scheme also resists forgery attacks on cloud service providers. The scheme is based on the homomorphic verifiable response and the Hash index hierarchy. The responses from multiple cloud service providers can be combined into a single response. The computation and communication overhead for this scheme are less than those of the original scheme. The scheme satisfies completeness, knowledge soundness and zero-knowledge properties. Therefore, this scheme provides a practicable method for checking data integrity.