Verifiable keyword searchable encryption with enhanced security using aggregate key in blockchain-based smart healthcare

In the field of smart healthcare, Electronic health records (EHRs) play a key role in storing patient data. Typically, EHRs stored in different medical institutions are encrypted to protect the privacy of patients.When conducting searches and transmissions of EHRs between various medical institutions to improve medical collaboration, it is crucial to ensure the accuracy and correctness of the search results, as well as the security during the transmission process to protect patient data privacy. Unfortunately existing search technologies over encrypted EHRs in smart healthcare fail to simultaneously satisfy the accuracy of the search, verification of the search results, and the ability to resist attacks from internal and external adversaries. Consequently, we propose a novel verifiable keyword searchable encryption with enhanced security (ES-VKSE) scheme to cater to the search requirements in the context of smart healthcare. Our proposed ES-VKSE scheme implements multi-keyword searchable encryption, which makes the document search more flexible while not revealing the information of the document. Besides, our proposed scheme not only ensures the verification of search results for fair interaction among multiple parties, but also proves to be resistant to colluding attacks and trapdoor forging attacks. Extensive experimental evaluation demonstrates that our scheme significantly improves the search efficiency by 98%. Notably, during the verification phase, our scheme required only 6.35 s to process 50 documents with 11 keywords each. This substantial improvement in search and verification efficiency makes it an ideal solution for real-time EHRs retrieval in smart healthcare systems.