A Scalable and Secure Outsourced IoT Electronic Health Records with Efficient User Revocation Using Fog-Assisted Cloud Model

The management of Electronic Health Records (EHRs) from IoT devices has become essential with the integration of cloud computing and IoT technology in healthcare sector. Existing research works adopt cloud-based access control with the encryption solution to secure the outsourced EHRs. However, when it comes to the IoT cloud data sharing environment, where data originated from numerous devices and the authorization status of users is subject to frequent changes, there remains a gap in achieving secure and lightweight IoT data encryption and fine-grained sharing with efficient user revocation procedures. This paper proposes a cloud-based access control scheme with efficient and scalable revocation to support fine-grained, secure, and efficient revocation for IoT based EHRs based on Ciphertext policy Attribute-based encryption (CP-ABE) and fog-assisted computing. The scheme introduces IoT data encryption and secure aggregation algorithm. In this scheme, the concept of outsourced encryption and decryption is leveraged to enable secure and lightweight access control in fog-cloud computing. Additionally, a novel revocation protocol is devised along with the use of graph database to enable efficient user revocation in a highly evolvable access control system. Finally, comparative analysis is conducted to demonstrate the security and efficiency of the proposed scheme.