Towards Secure and Transparent Cloud Auditing: A Blockchain and IPFS-Driven Framework with Batch Verification

With the rapid advancement of cloud storage and the increasing use of connected devices, uploading data to the cloud results in the loss of physical control by data owners, making confidentiality and integrity entirely dependent on Cloud Service Providers (CSPs). This raises concerns about whether CSPs effectively safeguard outsourced data, as any malicious behavior can lead to data tampering or deviation. Traditional auditing schemes rely on Third Party Authorities (TPAs), which are not always trustworthy. Although various cloud data auditing mechanisms have been proposed, few effectively address the challenge of ensuring data integrity without relying on trusted third parties. To overcome this limitation, we propose a secure and efficient distributed blockchain-based data integrity auditing scheme. Specifically, our approach randomly assigns the audit task to a user selected from among the system participants via blockchain. Blockchain and InterPlanetary File System (IPFS) technologies are leveraged to enforce access control. Furthermore, the proposed scheme supports low-cost batch integrity verification without the need for a TPA. Theoretical analyses confirm that our solution ensures data traceability and auditability, and reduces reliance on third parties. Finally, our simulations show that proof generation remains under 0.7 seconds for 600 data blocks at 256-bit security, while verification costs remain negligible.