Efficient Construction of Order-Preserving Encryption Using Pseudo Random Function

Order-Preserving Encryption (OPE) is an encryption system that preserves the numerical (or alphabetical) order of plaintexts. Since many operations of communications and databases are based on order relations of data (plaintexts), OPE is regarded as a core technique for various applications. However, the intrinsic property of OPE makes constructing an efficient and secure OPE system hard to achieve. In particular, OPE can guarantee only limited security compared to general encryption systems. Only a few results on OPE systems were presented, and no theoretical research based on provable security has been presented until recently. Lately, some approaches have been suggested. However, every known result is unsatisfactory for formalizing the provable security of OPE systems. In this paper, we propose a new OPE system that employs only a simple pseudorandom number function, and therefore has an advantage for practical usage.