Abstract:A cloud audit scheme is a mechanism that helps a data owner (DO) verify the integrity of data stored on cloud servers. Existing schemes mainly focus on the scenario of a single DO and are not suitable for group uploaders, who need to manage members’ keys and revoke users with low credit values. To address these issues, this study proposes an audit scheme for multiple DOs, in which group members coordinate their keys, and a proxy performs the revocation operation. However, this scheme has issues such as unchanged tags during the revocation process, privacy leakage risks during the audit phase, and an excessive number of tags during the data uploading phase. Based on this, the study improves the existing scheme and proposes an efficient blockchain-assisted audit scheme for multiple DOs. During the revocation process, member information is incorporated into tag generation to ensure the effectiveness of revocation. During the audit phase, timestamp-based challenge message generation ensures data privacy. During the tag generation phase, a more flexible data partitioning method is adopted to significantly reduce the number of tags and optimize system performance. Finally, detailed security analyses and experimental simulations demonstrate that the proposed scheme offers advantages in auditing and privacy protection while achieving competitive performance.