Ciphertext Range Query Scheme Against Agent Transfer and Permission Extension Attacks for Cloud Computing

Range query is commonly used to support ciphertext retrieval on encrypted databases in a cloud-based environment, and order-revealing encryption (ORE) plays an increasingly important role in range query for ciphertext field processing. Specifically, one can utilize ORE to facilitate comparators to determine whether the order of ciphertext(s) corresponds to the associated plaintext(s). Newer ORE designs include those that are resistant to common attacks (e.g., spectral attacks) and those that are capable of supporting both multiclient and single-client settings. However, in the scenario of cross-database range queries, existing multiclient ORE approaches generally pass the data owner’s query key to the searcher during the authorization process. Consequently, this results in agent transfer and permission extension, which can be exploited to facilitate unauthorized access to the database data. To solve these limitations, we propose om-ORE. The latter uses the oblivious pseudorandom function (OPRF) protocol to further enhance the security of token generation mechanism in ORE, and is designed to ensure that neither the data owner nor the authorized client reveals any secret key or expected query range to each other. Using the proposed om-ORE scheme as a building block, we design a secure multiclient ciphertext range query scheme that is resilient to both agent transfer and permission extension attacks. The performance evaluation shows that om-ORE inherits the advantages of state-of-the-art multiclient ORE approaches, in terms of ciphertext size and comparison efficiency, as well as having comparable performance in the token generation process.