Searchable encryption using secret sharing scheme that realizes direct search of encrypted documents and disjunctive search of multiple keywords

Abstract

The main search functions realized by searchable encryption can be classified into the search function using one query and that using multiple queries. Searchable encryption using one query has been widely studied and researched; however, few searchable encryption methods can accommodate the search function using multiple queries. Additionally, most of the methods proposed thus far utilize the concept of index search. Therefore, an additional process of updating or deleting an index when new documents are added or removed is required, increasing the overall computational cost. Furthermore, a document that is not registered in the index cannot be searched. Therefore, herein, using a secret sharing scheme that is known to offer a low computational cost, we propose a method that can realize the direct search function over sentences using the conjunctive search function without the construction of any index. We also propose a method that realizes the search function with multiple search queries using the disjunctive search function. Additionally, we implement our proposed methods, and demonstrate that they can perform a direct search over sentences using multiple keywords.