The storage of electronic medical records (EMRs) is an area of extensive research, and healthcare systems often delegate this task to cloud service providers (CSP). Typically, CSP transmits the encrypted EMRs to a cloud server with a searchable encryption scheme for easy retrieval. However, the enormous power held by centralized CSP poses a potential threat to patients’ personal privacy, as it can lead to unauthorized access and misuse of medical data by both CSP and data users, such as doctors. This paper proposes a blockchain-based multi-keyword searchable encryption (BMSE) electronic medical record solution. The scheme consists of two parts. On the one hand, our solution involves the integration of blockchain technology and the utilization of advanced encryption standard (AES) for symmetric data encryption. Additionally, we employ attribute-based encryption (ABE) to encrypt the search index. This approach aims to address the issue of excessive power held by centralized CSP, which can potentially result in the compromise of patients’ privacy. On the other hand, we use the K-means algorithm to cluster the documents, and use the relevance score of keywords and documents as the search index to solve the problem of low efficiency of the existing multi-keyword searchable encryption schemes. Finally, we verify the safety of BMSE through safety analysis, and the experimental analysis shows that BMSE improves the search efficiency.

电子病历(EMR) 的存储是一个广泛研究的领域，医疗保健系统通常将此任务委托给云服务提供商 (CSP)。通常，CSP 使用可搜索的加密方案将加密的 EMR 传输到云服务器，以便于检索。然而，中心化 CSP 拥有的巨大权力对患者的个人隐私构成了潜在威胁，因为它可能导致 CSP 和数据用户（例如医生）未经授权访问和滥用医疗数据。本文提出了一种基于区块链的多关键字可搜索加密（BMSE）电子病历解决方案。该方案由两部分组成。一方面，我们的解决方案涉及区块链技术的集成和利用高级加密标准（AES）进行对称数据加密。此外，我们采用基于属性的加密（ABE）来加密搜索索引。这种方法旨在解决中心化 CSP 权力过大的问题，这可能会导致患者隐私受到损害。另一方面，我们利用K-means算法对文档进行聚类，并利用关键词与文档的相关性得分作为搜索索引，解决现有多关键词可搜索加密方案效率低下的问题。最后，我们通过安全性分析验证了BMSE的安全性，实验分析表明BMSE提高了搜索效率。