Flexible and Efficient Blockchain-Based ABE Scheme With Multi-Authority for Medical on Demand in Telemedicine System

Telemedicine offers a medical-on-demand (MoD) service from a distance. This technology is designed to overcome distance barriers and improve the process of accessing medical services in distant rural communities. With the development of cloud computing, the MoD services in the telemedicine system are provided by the Cloud Service Provider (CSP). This CSP connects the patient and the medical staff in different places with both convenience and fidelity. Meanwhile, the outsourcing healthcare data on public cloud platforms bring some new challenges on the security. Although attribute-based encryption (ABE) algorithm realizes flexible and fine-grained access control, a large number of patients subscribe or unsubscribe the different medical services frequently in the cloud, which takes a huge cost for membership management. In this paper, an ABE scheme is presented to achieve the dynamic authentication and authorization with higher flexibility and efficiency for the MoD services in telemedicine system. On the one hand, when the patient alters his ordered service, it requires no updating on the parameters for those whose statuses remain unchanged. We construct an independent-update key policy ABE scheme in the distributed telemedicine system that aims to updates patient's keys separately, and there are multiple authorities to manage this system altogether which is more similar to the real situation. On the other hand, by using blockchain and distributed database technologies, the private healthcare data stored in public cloud is protected in integrity, which avoids the misdiagnosis accident from the inaccurate electronic health records distorted by a malicious user or authority from the inner cloud. Finally, we analyze the collusion attack in multiple authorities and formally prove the security of this protocol in a standard model. After comparing and simulating, the results of this work show a better performance.