An anonymous and large-universe data-sharing scheme with traceability for medical cloud storage

The application of medical cloud storage technology in healthcare and the sharing of electronic medical records (EMR) bring convenience for patients and medical institutes. However, two barriers limit further expansions of the above (i.e. key escrow and key abuse issues). In this paper, we construct a large universe data-sharing scheme based on attribute-based encryption. We design all attribute authorities simultaneously to participate in the key computation, and the user performs aggregation. By issuing anonymous credentials to the recipients, their identity information is protected. To achieve complete tracing of the traitor, we blend the two mechanisms, white-box traceability and black-box traceability, together. Detailed security proofs have been carried out for various types of possible attackers, and theoretical analyses have verified the security of the proposed scheme. We performed performance evaluations in conjunction with existing schemes, and numerical experience shows that the burden on the user side is also minimal.