Identity-based public data integrity verification scheme in cloud storage system via blockchain

Almost all existing data integrity verification schemes upload outsourced files and tags set to the CSP simultaneously. Thus, in this paper, we provide a novel idea to construct the integrity verification scheme via blockchain. The construction of the proposed scheme is based on identity-based encryption (IBE) which avoids the complex certificate management caused by the public key infrastructure (PKI). Our scheme decides to upload tags set to the blockchain to achieve the separate storage of the tags set and files. The characteristics of the blockchain determine that the tags set will not be forged. But separate storage may cause the information returned by the three parties participating in the public auditing to be out of sync; thus, a small data structure—audit log is introduced to solve this problem. The advantages of audit log can not only guarantee the correct and smooth implementation of the proposed scheme, but also prove the TPA’s innocence when necessary. Moreover, the security of our scheme is strictly proved. Finally, a series of performance evaluations demonstrate that our scheme is efficient and feasible.