Asynchronous Federated Attribute Distribution: A Scalable Blockchain-Integrated Access Control Framework for Secure Health Data Sharing

Abstract

Wireless Body Area Networks (WBANs) can offer continuous health monitoring, but they lack secure and scalable access control mechanisms for sensitive medical data. Traditional attribute-based access control systems rely on centralised credential authorities, introducing single points of failure and trust bottlenecks. In this paper, we propose a decentralised access control framework based on asynchronous federated attribute distribution system and integrated with consortium blockchain technology. The framework eliminates dependence on centralised authorities through the inclusion of verifiable secret sharing, high-threshold distributed key generation, and smart contract-based policy enforcement. The proposed architecture is composed of three core components: (i) an asynchronous distributed key generation module, (ii) a verifiable attribute secret sharing module, and (iii) a smart contract orchestration layer. The participating healthcare institutions collaboratively create and maintain a distributed master secret without explicit reconstruction. Attribute-specific decryption keys are created by using a high-threshold Shamir secret-sharing scheme. Smart contracts evaluate access requests by checking ciphertext-policy attribute-based encryption (CP-ABE) policies against on-chain attributes. Once the policy has been validated successfully, authorised parties collaborate to reconstruct the required secret keys to decrypt the data. All access operations are permanently logged on the blockchain for transparency and auditability. The framework exhibits strong collusion resistance as a threshold number of institutions are necessary to compromise the system secrets. The framework is asynchronous in its execution, thus guaranteeing operational liveness in the face of network delays. Localised committee for efficient attribute revocation reduces the management overhead. The proposed framework is implemented using pairing-friendly elliptic curve cryptography and Hyperledger Fabric in WBAN environment. The proposed framework is secure, scalable and transparent for decentralising health data sharing.