Time‐specific encrypted range query with minimum leakage disclosure

Abstract A time‐specific encrypted range query scheme that has the following properties is proposed. (1) The proposed scheme has trapdoor privacy and data privacy so that a semi‐honest cloud is not able to get any useful information from given ciphertexts and given tokens that are used for searching ranges. (2) Unlike most of the other studies which report that the cloud server stores single encrypted keyword/element in the database, in our solution, the cloud server stores encrypted multi‐keywords/ranges in the database. Therefore, the semi‐honest cloud compares ciphertexts to tokens as ranges based on a predefined threshold ϕ value. This approach decreases the cloud search time since the cloud compares ranges to ranges (multi‐keywords with multi‐keywords) not points to points (not a keyword with a keyword). Thus, the proposed scheme is efficient based on searching ranges on ciphertexts. (3) Moreover, the communication cost between users and the cloud is decreased from O(n) to O(log n), where n is the size of a range. Users send logarithmic size information to the cloud server instead of sending linear size information.