Enhancing Medical Data Sharing with an Attribute-Based Dynamic Verifiable Searchable Encryption Scheme Using Blockchain

Searchable encryption (SE) can retrieve ciphertext without decrypting it, effectively meeting the privacy protection needs for medical data sharing in cloud environments. However, SE applications in medical data sharing also face issues related to data security and the trustworthiness of results. To ensure that unauthorized users cannot access medical data, fine-grained access control is necessary. Additionally, since cloud servers may return tampered results to data users, the verification of returned results is also required. To this end, we propose an attribute-based dynamic verifiable searchable encryption scheme that utilizes attribute-based encryption for fine-grained access control, and guarantees forward security during the update process by maintaining the update state locally for keyword ciphertext updating. Our scheme leverages the tamper-proof feature of blockchain to verify search results by designing a smart contract, thus ensuring the trustworthiness of the results and the fairness of the verification. Combined with the designed authentication tag with cumulative and updating properties, our scheme can be applied to the dynamic data update scenarios. Finally, we formally prove the security of the proposed scheme, and experimental results show that the scheme has better efficiency in keyword encrypt and keyword search phases.