Quantum privacy query protocol based on counterfactual quantum key distribution with noiseless attack

Abstract To save quantum resources and improve efficiency, this article proposes an efficient counterfactual quantum privacy query protocol. Counterfactual quantum privacy query refers to the identification of secure detection and key screening based on the detector's response results without the actual transmission of quantum information between user Bob and database Alice. Alice completes key transmission through a counterfactual device, while Bob measures the photon's polarization with a probability of 1/2 to obtain the encoded classical information, followed by traditional post-processing and privacy query operations. Additionally, to withstand the noise impact during the communication process, a modified counterfactual QKD protocol proposed by Rao (2021) is utilized, where communication parties randomly select a quantum bit flip with a specified probability \textit{f}, and then complete the quantum privacy query.