Privacy-preserving, traceable dual access control with multi-keyword search in E-health cloud

Electronic healthcare (E-health) cloud system leverages attribute-based encryption (ABE) to ensure electronic health records (EHRs) confidentiality and provide fine-grained access control for secure sharing and improved diagnostic efficiency. To prevent Economic Denial of Sustainability (EDoS) attacks from disrupting normal user download request access control mechanisms, the ABE-based dual access control scheme has been proposed. Unfortunately, existing ABE-based dual access control schemes still have the following defects: (1) no efficient way to locate encrypted EHRs stored in E-health cloud; (2) lack an effective malicious user tracking and revocation mechanism; (3) access control mechanism exposes sensitive patient information. In this paper, we tackle these challenges and present a privacy-preserving, traceable dual access control mechanism supporting multi-keyword search in E-Health cloud. We introduce keyword search to locate encrypted EHRs that doctors need to download. A white-box traceability and revocability mechanism is employed to trace malicious users and revoke their authorization. Patient privacy in policies is protected via a partially hidden policy, which reveals attribute names but keeps their values hidden. Experiments show our scheme offers comprehensive functionality with reasonable overhead.