Decentralised health record management with blockchain: privacy and security in cloud-based systems

The rise of Electronic Health Records (EHRs) has created a new challenge for healthcare organisations: how to manage, share and secure the growing amounts of health data. Conventional cloud-based EHR systems remain susceptible to centralised trust, limited auditability, and inflexible access-control mechanisms, and most existing blockchain-based systems don’t collectively support adaptive policy enforcement, privacy-preserving authentication, and anomaly-aware access validation. To address these limitations, this paper introduces the decentralised EHR management framework HealthBlockSecure, which combines permissioned blockchain infrastructure, encrypted off-chain storage, authentication with zero-knowledge proofs (ZKPs), decentralised identities, smart-contract-based policy enforcement, and the PrivAccessNet deep learning model. PrivAccessNet can provide context-aware access validation and anomaly detection based on request and policy attributes, and the external ZKP verification service can provide minimal-disclosure authentication without revealing sensitive identity information. Experimental evaluation with SyntheticMass and MIMIC-IV showed a mean access-violation prevention rate of 96.3% for five re-experiments and an audit-verification accuracy of 99.2%. It also identified all simulated tampering attempts using SHA-256 integrity verification. In general, HealthBlockSecure delivers an integrated solution for privacy-sensitive, auditable, and adaptive management of access to EHRs, with secure-access validation latency measured in the near-real-time range. The complete HealthBlockSecure implementation is publicly available at https://github.com/Sripada-RamaSree/HealthBlockSecure .