A Multi-Semantic Scheme to Verifiable EHRs Retrieval for Cloud-Based Telemedicine

As the cornerstone of telemedicine, Electronic Health Records (EHRs) not only reduce clinical costs but also enable precision diagnostics. As medical institutions increasingly outsource EHRs to Cloud Service Providers (CSPs), dual challenges have emerged as critical issues: preserving patient privacy and enhancing the search experience for medical personnel. While multi-keyword searchable encryption has gained significant attention in the medical domain as a potential solution, existing schemes have significant limitations in both practicality and security. First, the growing number of medical institutions complicates the management of key and privileges. Second, the impoverished search semantics in existing query mechanisms severely degrades the clinical user experience, creating unacceptable operational bottlenecks in medical practice. Furthermore, excessive reliance on CSPs leads to ignoring situations where the returned results are incorrect, impacting the availability and security of the telemedicine system. To address these limitations, we propose a Verifiable Multi-Semantic Keyword Search scheme (VMSKS) for EHRs in cloud-based telemedicine. To resolve the security requirements arising from the increasing medical institutions, we innovatively design a more efficient dual Secure k-Nearest Neighbor technique (SKNN) for key distribution. Meanwhile, fine-grained access control is implemented using access policy trees, ensuring the controllability of data access. This approach safeguards the privacy of EHRs. To support flexible EHR search for medical personnel, the prime Hadamard product encoding technique is exploited to provide queries that support multiple search semantics simultaneously. Given the potential unreliability of CSPs, VMSKS introduces a novel verification mechanism by constructing verification proofs during encryption, ensuring the authenticity and integrity of returned results. Theoretical analysis and experimental evaluation demonstrate the security and efficiency of VMSKS, respectively.