关键词: 区块链, 分片技术, 共识协议, 医疗电子病历(MER), 可搜索加密, 数据共享

Abstract: Aiming at the limited scalability of data sharing based on traditional blockchains, a scale-out and sharing scheme of blockchain based on sharding technology was proposed. First, performed network sharding based on the periodic jump consistent hash algorithm that greatly reduced the risk of sybil attacks in a single shard; second, used the SBFT consensus protocol in the shard to reduce the high communication complexity of the Pratic Byzantic Fault Torent (PBFT) consensus protocol, and the use of a two-layer architecture between the physical multi-chain of shards and the logical single main chain reduced the storage pressure of the members of the shard; finally, proposed a searchable encryption sharing scheme based on Public Key Encryption with Conjunctive Field Keyword Search (PECKS) on the medical consortium blockchain, that improved the patient's control over their sensitive data, and realized the fine-grained search of sensitive data under encryption. Through performance analysis, under the parallel sharding structure, the throughput of the blockchain had significantly increased with the increase of shards, and the retrieval efficiency had also been significantly improved. The experimental results showed that the proposed scheme can greatly improve the efficiency and scalability of the system.

Key words: block chain, sharding technology, consensus protocol, Medical Electronic Record (MER), searchable encryption, data sharding