Deniable Time Signature Forward Secure Searchable Encryption With Flexible Retrieval and Traceable Authorization in Sharable EHR
Nan Gao, Kai Fan, Kan Yang, Hui Li, Yintang Yang · IEEE Transactions on Dependable and Secure Computing · 2025
Electronic Health Record (EHR) sharing can improve the accuracy of medical diagnosis and promote the development of the public medical field. However, plaintext medical records expose patient privacy, and it is challenging to share medical records between different hospitals, making it difficult for doctors to securely retrieve medical records and massively analyze the same diseases from different patients. In this paper, we propose a flexible ciphertext retrieval scheme in electronic health sharing system that supports multi-patient and multi-keyword medical records retrieval. The proxy free ciphertext retrieval technology based on cloud servers enables doctors to retrieve multiple patients' medical records simultaneously. On this basis, we utilize the time encoding algorithm to ensure that the trapdoor associated with the old time cannot retrieve the ciphertext index bound with the latest time, so as to realize the lightweight forward security. Besides, the encoding time signed by the deniable signature can avoid forgery by malicious users or adversaries. In addition, the scheme supports evil user traceable and revocable. The security analysis indicates that the scheme can satisfy the keyword privacy, the forward security of updated ciphertexts, and the deniability of time encoding signatures. Experimental evaluation illustrates that our scheme is lightweight and efficient