Fine-grained access control with decentralized delegation for collaborative healthcare systems

Collaborative treatment has emerged as a crucial approach for improving the quality and efficiency of medical services in modern healthcare systems. To support this paradigm, secure access control over electronic health records (EHR) and flexible delegation of patient permissions are essential for enabling efficient, privacy-preserving data sharing. This paper proposes a fine-grained access control scheme with decentralized permission delegation tailored for medical collaboration scenarios. To ensure fine-grained access control, we adopt a hybrid encryption scheme that combines a dual-key regression tree with Identity-Based Encryption with Wildcard Key Derivation (WKD-IBE) for efficient and scalable key management. This integration enables access control based on data attributes rather than user identities and adheres to the principle of minimal data disclosure. To support decentralized permission delegation, we extend the WKD-IBE scheme to enable patients to authorize multiple doctors to grant access permissions collaboratively. This extension ensures controlled delegation by enforcing a predefined threshold of doctors and requiring consensus on the requested access scope. Additionally, we provide both theoretical and practical security analyses, along with an implementation to demonstrate the scheme’s real-world applicability. Experimental results demonstrate that our scheme achieves lower authorization latency and better scalability in collaborative healthcare scenarios while maintaining comparable encryption efficiency.