Blockchain-based Bidirectional Updates on Fine-grained Medical Data

Electronic medical data sharing between stakeholders, such as patients, doctors, and researchers, can promote more effective medical treatment collaboratively. These sensitive and private data should only be accessed by authorized users. Given a total medical data, users may care about parts of them and other unrelated information might interfere with the user-interested data search and increase the risk of exposure. Besides accessing these data, users may want to update them and propagate to other sharing peers so that all peers keep identical data after each update. To satisfy these requirements, in this paper we propose a medical data sharing architecture that addresses the permission control using smart contracts on blockchain and splits data into fined-grained pieces shared with different peers then synchronize full data and these pieces with bidirectional transformations. Medical data reside on each user's local database and permission-related data are stored on smart contracts. Only all peers have gained the newest shared data after updates can they start to do next operations on it, which are enforced by smart contracts. Blockchain-based immutable shared ledge enables users to trace data updates history. This paper can provide a new perspective to view full medical data as different slices to be shared with various peers but consistency after updates between them are still promised, which can protect privacy and improve data search efficiency.