Abstract
Due to regulations and policies enacted to protect patients’ privacy, electronic health records (EHRs) must be kept as sensitive information in a secure and reliable manner. Maintaining EHRs by hospitals and safely sharing them with others have proved to be challenging tasks. In this thesis, we introduce a cloud-based hospital blockchain (CHB) scheme to allow for big data, such as EHRs in multimedia file format, to be stored in hospitals’ private clouds in a way that achieves data accessibility, redundancy, and security. Its counterpart scheme, lite hospital blockchain (LHB), is introduced to allow for the storage of metadata and text-based information about EHRs on end users’ local machines. Our approach enables end users to efficiently retrieves EHRs stored within CHBs via their LHBs without experiencing the burden of storing large amount of big data on their local machines. To address the scalability issue of this approach, we further introduce a hierarchical cloud-based consortium blockchain framework to significantly increase the scope of the method. The new framework supports the storing and sharing of EHRs between hospitals in different hospital blockchain networks through high-level blockchain networks, called city blockchain networks and state blockchain network. To restrict and grant access of the data to authorized participants only, we present our data security mechanism along with role-based access control (RBAC) policies. We also present the procedures for concurrently searching EHRs, creating RBAC policies, and retrieving EHRs through the hierarchical blockchain networks. The experimental results show that our approach is feasible and efficient ivfor accessing and sharing EHRs stored both locally and in clouds regardless of their geographical differences throughout a country.