CRSQ-KASE: Key Aggregate Searchable Encryption Supporting Conjunctive Range and Sort Query on Multi-owner Encrypted Data

Abstract

The existing key aggregate searchable encryption (KASE) schemes allow searches on the encrypted dataset using a single query trapdoor, with a feature to delegate the search rights of multiple files using a constant-size key. However, the limitation of the existing KASE schemes is they only support the exact keyword match $$ (Keyword = Value)$$ search query for a single query keyword. In addition, to perform a conjunctive keyword search using the existing KASE schemes, the user requires to submit different trapdoors for each individual keyword to the server. Considering the existence of numeric keywords, the KASE should support different types of query such as range query$$ (Value_1 \le Keyword \le Value_2) $$, comparison query($$ (Keyword \ge Value)$$ or $$ (Keyword \le Value)$$), and sort query. Therefore, a novel KASE scheme is proposed in this paper that supports the conjunctive range and sort query (i.e., CRSQ-KASE) on the encrypted dataset and enhances the query expressiveness of the existing KASE schemes. The proposed CRSQ-KASE scheme supports search among different keyword fields considering both numeric and non-numeric keywords. The user can search over shared encrypted dataset by giving arbitrary conjunctive queries $$ (Keyword_1 = Value_1\wedge Keyword_2 \le Value_2 \wedge \cdots \wedge Value_{n_1} \le Keyword_n \le Value_{n_2}) $$ using a single trapdoor. Furthermore, in the multi-owner setting, the user can search over multiple users’ documents set using a single query trapdoor. The theoretical, empirical, and security analyses show that the proposed CRSQ-KASE scheme performs better than the existing KASE schemes. To the best of our knowledge, the CRSQ-KASE is the first attempt that efficiently supports multi-dimensional, conjunctive keyword searches on the multi-owner encrypted dataset and gives the sorted search result.