Secure Medical Data Sharing Featuring Traceable Data Usage and Automatic Audit Mechanism

At present, cloud computing provides flexible and cost-effective solutions for sharing medical data, particularly electronic health records (EHRs), which are widely used by resource-limited healthcare institutions. However, the sensitive nature of patient data demands strong encryption and privacy protection. Additionally, ensuring data traceability-tracking and monitoring data sources and usage remains a crucial yet unresolved challenge. Current solutions prioritize data integrity during sharing but lack transparency, traceability, and comprehensive integrity audits for cloud-stored medical data. To overcome these limitations, this paper puts forward a blockchain-based framework for medical data sharing, enabling traceable data usage and integrating automatic audit mechanism. Our scheme adopts smart contracts on the blockchain to verify search results, audit cloud data integrity, and allocate service fees equitably based on audits. The proposed solution ensures the integrity of data during the sharing process and storage, while fostering financial fairness between users and cloud service providers. Rigorous experiments demonstrate that our scheme substantially improves verification efficiency, achieving up to a 95% reduction in smart contract gas consumption and an 80%–85% decrease in post-update verification latency compared to existing state-of-the-art methods, making it highly suitable for medical data-sharing environments characterized by frequent updates and stringent data integrity requirements.