Fine-Grained Authorized Encrypted-Data Retrieval Mechanism Based on Boolean Query Searchable KP-ABE Framework

To improve the efficiency of searching and retrieving encrypted data while minimizing the computational burden on users’ devices within the key-policy attribute-based encryption (KP-ABE) framework, we introduce a new scheme called fine-grained authorized encrypted-data retrieval mechanism (FineDReaM) that is a novel Boolean query searchable KP-ABE mechanism. This method supports comprehensive Boolean search capabilities over encrypted content, maintains keyword privacy, ensures only authorized users can search, enables outsourced decryption, and allows users to verify both search results and outsourced decryption—all in one unified system. FineDReaM is resistant to keyword guessing attacks for both search tokens and ciphertexts, so unauthorized parties cannot deduce sensitive keywords. Data access is strictly limited to authorized users, and the scheme is designed so that user-side decryption remains fast and efficient. Additionally, FineDReaM includes a noninteractive verification mechanism, empowering users to independently confirm the integrity of both search results and outsourced decryption, without the need to contact a third party. We also introduce robust and generalized security definitions that consider various attack scenarios. Our security analysis demonstrates that FineDReaM achieves not only data confidentiality and keyword privacy, but also strong guarantees of verifiability under the random oracle model.