基于区块链和亲友节点的电子健康记录安全共享方案

区块链技术在电子健康记录安全共享上具有巨大潜力，然而，目前的解决方案存在着如存储空间大和共识效率低等问题。为此，提出了一种基于区块链和亲友节点的新方案。首先，采用分布式文件系统将用户完整的电子健康记录存储在线下服务器，并构建用户的亲友节点集，每个用户的数据由其亲友节点冗余存储，链上仅存储区块头信息，降低了存储空间；其次，设计了基于多签名技术的数据访问机制，采用Shamir秘密共享机制将用户的私钥分发给其亲友节点，亲友节点中的过半数可以利用自己的私钥重建出用户私钥，解决紧急情况下的数据访问问题；最后提出了基于信用的拜占庭容错共识机制，将信用值排名前10%的节点作为领导者节点集，采用随机算法在领导者节点集中生成主节点，提高了共识安全性。实验结果表明，所提方案所需的链上存储空间是现有方案的1/7，数据访问效率提高了15倍，同时在保证较好时延和吞吐量的情况下，具有更高的共识安全性。所提方案可实现电子健康记录的安全高效共享，为区块链在医疗领域应用提供案例。

Secure electronic health records sharing scheme based on blockchain and friend and relative nodes

Blockchain technology has great potentiality in the secure sharing of electronic health records. However, current solutions face issues such as large storage space and low consensus efficiency. This paper proposed a novel scheme based on blockchain and multi-signature technology. Firstly, this paper adopted a distributed file system to store users'' complete electronic health records on offline servers, and constructed a set of user''s friend and relative nodes, which was just responsible for storing user''s data redundantly. Specially, this paper just stored block''s header information on the chain, which reduced storage space. Then, this paper designed a data access mechanism based on multi-signature technology, using Shamir secret sharing mechanism to distribute user''s private keys to their relatives and friends. More than half of the relatives and friends could use their own private keys to reconstruct users'' private keys, solving data access problems in emergency situations. Finally, this paper proposed a credit based Byzantine fault-tolerant consensus mechanism, which used the top 10% nodes with credit values as the leader node set and utilized a random algorithm to generate the master node in the leader node set. And it improved consensus security. The experimental results show that compared with existing methods, the proposed scheme reduces the on-chain storage space by 1/7, improves data access efficiency by 15 times, and has higher consensus security while ensuring good latency and throughput. The proposed scheme can achieve secure and efficient sharing of electronic health records, providing a case for the application of blockchain in the medical field.