A Blockchain-Based Framework for Privacy-Preserving Medical Report Sharing and Diagnosis-Free Verification

The digital sharing of healthcare data necessitates a careful balance between the need for verifiability and the protection of patient privacy. In many real-world scenarios, particularly in employer and third-party verification processes, excessive clinical information is disclosed beyond what is strictly required. This practice introduces significant privacy risks and conflicts with data minimization principles. To address this problem, this study proposes a blockchain-based, privacy-preserving system architecture that enables health report verification without revealing diagnosis information. The proposed system is built upon a dual-layer architecture that structurally separates clinical data from verification processes. In the clinical data layer, health reports are encrypted on the client side and stored in off-chain environments, while only reference data and access control information are recorded on the blockchain. The system further integrates revocation mechanisms, role-based access control, and auditability through a modular smart contract design. In conclusion, this study introduces a modular, privacy-oriented, and practically applicable solution for secure healthcare data verification. By eliminating the need for clinical data disclosure during verification, the proposed architecture offers a novel design perspective and contributes both conceptually and technically to the development of blockchain-based healthcare information systems.