Cloud-assisted electronic health record (EHR) sharing plays an important role in modern healthcare systems but faces threats of distrust and non-traceability. The advent of blockchain offers an attractive solution to overcome this issue. Many efforts are devoted to promoting secure, flexible, and multi-featured blockchain-based EHR sharing. Yet, the problem of seeking out suitable healthcare providers and communicating information beyond the EHR has unfortunately been ignored. In this paper, we propose SeCoSe, a novel EHR sharing scheme to address these concerns. SeCoSe enables patients and their general practitioners to autonomously seek out and stay in touch with their preferred healthcare professionals. Specifically, a searchable and repeatable transformation identity-based encryption (SRTIBE) is proposed to achieve dynamic and flexible authorization updates. Moreover, we design attribute-identity mapping contracts and evidence-based contracts on the blockchain to enable on-demand retrieval of anonymous identities and ensure tamper resistance and traceability of system transactions. Furthermore, we employ the advanced messages on-chain protocol (AMOP) to facilitate the online communication of off-chain messages. Detailed security analysis and extensive evaluations demonstrate that SeCoSe is privacy-secure, traceable, and attack-resistant. SeCoSe has lower overhead for repeated authorization and transformation, on-chain transactions can be responded to within seconds, and online communication can handle the transmission of 49,000 messages in about 6 seconds.

中文翻译：

---

SeCoSe：迈向可搜索、可通信的医疗服务，寻求灵活、安全的 EHR 共享

云辅助电子健康记录 (EHR) 共享在现代医疗保健系统中发挥着重要作用，但面临不信任和不可追踪性的威胁。区块链的出现为解决这个问题提供了一个有吸引力的解决方案。许多努力致力于促进安全、灵活和多功能的基于区块链的 EHR 共享。然而，不幸的是，寻找合适的医疗保健提供者和在电子病历之外传达信息的问题却被忽视了。在本文中，我们提出了 SeCoSe，一种新颖的 EHR 共享方案来解决这些问题。 SeCoSe 使患者及其全科医生能够自主寻找他们首选的医疗保健专业人员并与其保持联系。具体来说，提出了一种可搜索且可重复的基于身份转换的加密（SRTIBE）来实现动态灵活的授权更新。此外，我们在区块链上设计了属性-身份映射合约和基于证据的合约，以实现匿名身份的按需检索，并确保系统交易的防篡改和可追溯性。此外，我们采用高级消息链上协议（AMOP）来促进链下消息的在线通信。详细的安全分析和广泛的评估表明 SeCoSe 具有隐私安全、可追溯和抗攻击的特点。 SeCoSe 重复授权和转换的开销较低，链上交易可在秒级内响应，在线通信可在约 6 秒内处理 49,000 条消息的传输。