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

摘要： 针对医疗机构之间共享电子病历所面临的挑战，如隐私泄露风险和低效的检索问题，提出一种基于区块链的电子病历高效加密检索与共享方案.首先，该方案一方面通过在云服务器上存储加密后的电子病历，并在联盟链上实施检索过程，有效地实现了存储与检索的分离；另一方面加入混淆陷门集合，从而显著降低了关键字猜测攻击的风险.其次，考虑到医疗数据的特殊性，提出一种优化的倒排索引结构，有效解决了处理大量电子病历时的检索效率问题.最后，基于此索引结构，开发了一种密文检索算法，该算法通过结合可搜索加密中的陷门技术和倒排索引中的关键字密文，实现了高效的密文检索.实验结果显示，该方案在实现隐私保护的前提下，成功解决了医疗行业电子病历共享的问题，同时显著提升了系统的运行效率.

关键词: 区块链, 可搜索加密, 隐私保护, 国密算法, 数据共享