Design And Analysis Of Quantum Private Query Protocols

Quantum cryptography is a new field that accompanies the rise of quantum computing,and it is a combination of classical cryptography and quantum mechanics.Quantum computing has powerful computing capabilities,and attackers can use it to solve specific mathematical problems and computational complexity assumptions that classic cryptography relies on in a short period of time to obtain secret messages.In order to solve the problem of classical cryptography cracked by quantum computing attacks,quantum cryptography has become a research hotspot in recent years and has derived many branches,including quantum key distribution,quantum signatures,quantum oblivious transfer,and quantum private queries studied in this paper.Quantum private query(QPQ)is an important branch of quantum cryptography,which aims to solve the problem of secure query security between users and databases.In practice,the QPQ protocol can be applied to scenarios such as business transactions and content privacy inquiries to protect the privacy of both parties.With the rapid development of quantum cryptography,various new types of attacks have emerged,such as false entanglement attacks and joint measurement attacks.Therefore,it is very necessary to study a more secure,practical and efficient QPQ protocol in view of the deficiencies in the existing QPQ protocol.In this paper,a novel classical post-processing algorithm and two kinds of robust quantum privacy query protocols are proposed for the existing deficiencies in QPQ protocol,and we analyze the security and feasibility of the protocol in theory.The details are as follows:(1)We propose a novel classical post-processing(CPP)algorithm for quantum key distribution(QKD)-based quantum private query.The CPP scheme reduces communication to a large extent,and the complexity of both parties has greatly improved the security.In addition,our protocol can provide a multi-bit query effectively.(2)We propose a novel quantum private query protocol in which the special way of classcal post-processing of oblivious key ensures the security against the joint-measurement(JM)attack.This protocol is a new one-way QPQ protocol.In addition,the protocol realizes perfect user privacy and lower complexity of communication.(3)We propose a robust QPQ protocol based on four-qubit decoherence-free(DF)states.In contrast to existing QPQ protocols against channel noise,only an alternative fixed sequence of single-qubit measurements is need by user(Alice)to measure the received DF state.This feature makes the protocol easier to use the current technology achieve.In addition,in order to maintain the advantages of flexible database queries,we reconstruct Alice’s measurement operators so that Alice needs only conditioned sequences of single-qubit measurements.