Research On The Security Of Quantum Key Distribution Based On The Weak Measurement And Weak Randomness

Quantum key distribution(QKD)is the art of sharing secret key between two different remote parties.QKD is a combination of quantum mechanism and cryptography,which can achieves information theory secure communication,where the information theory security refers to that the security of key is independent of the eavesdropper's calculation and storage capacity.Although the information theory security of the perfect QKD protocol has been fully proved,its practical devices have various non ideal characteristics,which will lead to the detector response error,side channel information leakage and even the devices of both sides of legal communication being remotely controlled.Therefore,the practical security research of QKD is very important.In this dissertation,the practical security of QKD is studied systematically based on weak measurement technology and weak randomness,The detailed work is as follows:1.We construct a weak measurement model in practical QKD system by applying weak measurement technology,and analyze the security of practical QKD protocol,and get a new way of monitoring the intercept-resend attack with the weak measurement model.Besides that,we construct a weak measurement model in Chain inequality and analyze Chain inequality violation with quantum weak measurement technology which can be applied to quantum communication in the network environment.1.1 We construct a weak measurement model in practical QKD system by applying weak measurement technology and analyze the security of practical QKD system.The theoretical security of ideal QKD protocol has been proved,but the practical QKD system have the problem of imperfect state preparation and state measurement equipment.In order to improve the security of practical QKD system,we propose the weak measurement model to monitor the intercept-resend attack.When the weak measurement parameter ? is(?),if there isn't intercept-resend attack,the quantum bit error rate between Alice and Charlie is 0,if there is intercept-resend attack,the quantum bit error rate is 25%,Thus the intercept-resend attack can be observed through the quantum bit error rate value between Alice and Charlie.1.2 We analyze the Chain inequality violation by applying weak measurement technology.Chain inequality is an important kind of Bell inequality.In this dissertation,we propose the weak measurement model to analyze the Chain inequality,we find that the double inequality violation can be observed in the case of n=2.In the case of n?3,two different parties can respectively realize the Chain inequality violation with different weak measurement parameters.2.We analyze the security of practical QKD protocol by applying weak randomness model.Due to the non-ideal characteristics of practical devices are equivalent to the weak randomness model,such as the blind attack and wavelength attack are equivalent to the randomness of coding being destroyed,we construct a weak randomness attack model to analyze the security of general QKD protocol.Then we construct a weak randomness attack model in decoy state QKD system,where the decoy state and signal state coding can be partially distinguished.And we analyze the security of decoy state QKD system under different weak randomness parameters,average photon number of light source and detection efficiency of receiver.2.1 We analyze the security of practical QKD protocol by applying weak randomness model.QKD protocol needs true random number for state preparation and state measurement,but using incomplete random number or imperfect quantum device will weaken the randomness.In our dissertation,we propose the weak randomness attack model of practical QKD system,and analyze the key rate of practical QKD system under weak randomness model.The result of security analysis shows that,even if a small part of basis selection is not completely random,it will be amplified with the loss of signal transmission in the channel,which will leads to the attack of QKD system.The numerical simulation results show that when the weak randomness parameter is 1%,the maximum transmission distance will be sharply reduced from 140 km to 12 km.2.2 We analyze the security of practical decoy state QKD protocol by applying weak randomness model.The practical decoy state QKD system needs to prepare indistinguishable signal state and decoy state to resist photon number splitting attack.However,the application of incomplete random numbers or imperfect quantum devices will weaken the indistinguishability.In the practical decoy QKD system,we propose the weak randomness attack model,the numerical simulation results show that when the weak random parameter is 1%,the maximum transmission distance will be sharply reduced from 140 km to 60 km.