Privacy-preserving and fine-grained data sharing for resource-constrained healthcare CPS devices

Medical cyber-physical systems (CPS) provide the possibility for real-time health monitoring of patients and flexible diagnostic services based on expert systems by collaboratively integrating and connecting various physical devices including sensors, terminals, and cloud infrastructure. However, the ubiquitous security threats in cyberspace have raised concerns about data security and user privacy. Although related works propose to protect data security and user privacy with cryptographic protocols, their heavy computational and storage overheads incur performance and battery life challenges for resource-constrained devices in the healthcare CPS. This article proposes an energy-saving and privacy-preserving data sharing (ESPPDS) scheme to address the challenge. ESPPDS inherits the anonymous fine-grained access control from attribute-based encryption (ABE) while protecting data integrity and supporting efficient user revocation. We also eliminate the repetitive computations of ciphertext components by utilizing the online/ offline encryption technology, and design a subtle and secure trick to delegate the decryption operations to the edge device, thereby reducing the computational overheads of the resource-constrained devices. We then show the security proof, and discuss the construction in the untrusted/ compromised server setting. The comparison and experiment indicate that ESPPDS is practical and more efficient than related schemes.