Novel classical post-processing for quantum key distribution-based quantum private query

Existing classical post-processing (CPP) schemes for quantum key distribution (QKD)-based quantum private queries (QPQs) including the kN -> N, N -> N, and rM -> N ones have been found imperfect in terms of communication efficiency and security. In this paper, we propose a novel CPP scheme for QKD-based QPQs. The proposed CPP scheme reduces the communication complexity and improves the security of QKD-based QPQ protocols largely. Furthermore, the proposed CPP scheme can provide a multi-bit query efficiently.