Lightweight And Fine-Grained Access Control For Cloud-Fog-Based Electronic Medical Record Sharing Systems

The electronic medical record (EMR) sharing systems promote medical services' efficiency, save human resources, and reduce energy consumption. A number of patients are ready to store their medical records in cloud. Nevertheless, owing to the medical record's privacy sensitivity, security problems are of critical importance in EMR sharing systems. This work presents a lightweight and fine-grained access control with data security for EMR sharing by combining fog and cloud using symmetric encryption algorithm and attribute-based encryption algorithm. Data owners encrypt the medical records with symmetric encryption and store them in cloud. The symmetric key is protected by ciphertext-policy attribute-based encryption and stored in fog. The keyword extracted from medical record is encrypted by data owner with key-policy attribute-based keyword search encryption and sent to fog. The requesters who satisfy with the keyword ciphertext's access policy can search for the keyword. They are capable of accessing the symmetric key if their attributes satisfy with the symmetric key ciphertext's access policy. The key management method and access control scheme guarantee the medical record's security and privacy. Security analysis demonstrates that our work is able to achieve privacy protection, secure search, fine-grained access control, and collusion resistance.