TCABRS: An Efficient Traceable Constant-Size Attribute-Based Ring Signature Scheme for Electronic Health Record System

With the flourishing of the e-healthcare industry, electronic health record (EHR) systems are being widely deployed, bringing new challenges in fine-grained authentication and tracing. Malicious publishers might upload improper files to the system, causing horrible harm to patients. Consequently, it is quite important to make sure that file publishers in EHR system can be easily authenticated and traced. Identity-based signatures provide coarse-grained authentication which only briefly tells identities. But attribute-based signatures can tell more details, making fine-grained authentication possible. In this paper, we propose an efficient traceable constant-size attribute-based ring signature scheme for electronic health record system, focusing on fine-grained authentication and traceability of file publishers. We give formal definitions of syntax and the security model and then propose a concrete scheme with a pair of link flags to achieve traceability. The security of our scheme is eventually proved under Diffie-Hellman assumptions in the standard model.