Cloud storage for electronic health records based on secret sharing with verifiable reconstruction outsourcing

Deploying electronic health records (EHRs) is now an undisputable trend in healthcare systems. Through affording benefits like flexibility and low cost, the cutting-cloud cloud storage is becoming a popular solution to store a massive amount of EHRs to depress the local storage. Nevertheless, storing sensitive information such as health records on the cloud incurs severe security and privacy risks. In this paper, we propose a novel cloud storage system for EHRs which fully ensures the data privacy by employing the Shamir's secret sharing. In this system, an EHR is divided into multiple segments by a healthcare center, and the segments are distributed to numerous cloud servers. When retrieving the EHR, the healthcare center captures segments from partial cloud servers and reconstructs the EHRs. Meanwhile, in reality, the reconstruction of a shared EHR could be much burdensome for a healthcare center or a patient, we thus propose a practical cloud storage scheme which outsources the reconstruction of a shared EHR to a cloud computing service provider. Such a solution can drastically boost the efficiency of the proposed scheme. As far as we know, our scheme is the first to define reconstruction outsourcing concept in all cloud storage schemes for EHRs based on secret sharing, and the results of outsourcing reconstruction can be verified by healthcare centers or patients in our scheme. The theoretical analysis and experimental results also support that our proposed scheme is secure and efficient.