关键词: 区块链, 可搜索加密, 隐私保护, 国密算法, 数据共享

Abstract: In response to the challenges faced by medical institutions in sharing electronic medical records, such as privacy leakage risks and inefficient retrieval issues, this paper proposes an efficient encrypted retrieval and sharing scheme for electronic medical records based on blockchain technology. We propose a blockchainbased scheme for efficient encryption, retrieval, and sharing of EMRs. Firstly, the scheme stores encrypted EMRs on cloud servers and implements the retrieval process on a consortium blockchain, effectively achieving separation of storage and retrieval. It incorporates a confusion trapdoor set, significantly reducing the risk of keyword guessing attacks. Secondly, considering the unique nature of medical data, we introduce an optimized inverted index structure that effectively resolves efficiency concerns when handling a large volume of EMRs. Lastly, based on this index structure, we develop a ciphertext retrieval algorithm that efficiently retrieves ciphertexts by combining searchable encryption’s trapdoor technique with keyword ciphertexts in the inverted index. Experimental results demonstrate that our proposed solution successfully addresses the challenges in the healthcare industry’s EMR sharing, enhancing system operational efficiency while ensuring privacy protection. 

Key words: blockchain, searchable encryption, privacy protection, state cryptography algorithms, data sharing