Blockchain-Enabled Privacy-Preserving Access Control for Electronic Health Records Using Smart Contracts

Electronic medical records are crucial for providing high-quality healthcare, but they also raise serious privacy and security issues. Traditional centralised storage systems are vulnerable to manipulation, hacking, and illegal access. This study suggests a smart contract-based blockchain architecture that provides decentralised, unaltered, and privacy-preserving access control for EMRs. The model integrates cryptographic techniques like AES-256 encryption and SHA-256 hashing for private data encryption, hybrid off-chain storage using IPFS for scalability, and Ethereum smart contracts for role-based rights management. Sequential procedures and computational formulas are used to explain the methods for secure storage and access verification. When compared to the conventional method, performance evaluation shows that the transaction latency for access verification is very low and that it is highly resistant to replay and collusion attacks with improved auditability. This approach has a security, transparency, and interoperability advantage with a marginally lower computing cost, according to the comparative study. Therefore, the provided architecture can serve as a workable and scalable solution for secure EMR management in dispersed healthcare settings, ad hoc for critical operational and compliance requirements. The integration of federated learning for privacy-preserving analytics will be the focus of future research. This concept would be effective in fostering patient trust and creating systems that guarantee safe data exchange between healthcare providers.