Research On Physical Layer Secret Key Generation Technology In Wireless Communication

The traditional wireless communication security technology represented by encryption and authentication based on cryptography makes use of computational complexity in the upper layer of the network to make encryption difficult.However,with the development of computing devices,the increase in computing power makes traditional encryption methods no longer secure.Different from traditional computing security,physical layer security technology starts from information theory security theory and guarantees communication security.It has gradually become a research hotspot at home and abroad.This thesis mainly researches the physical layer key generation technology under the background of wireless communication,mainly focusing on the channel quantization step in the key generation process.It analyzes three common quantization algorithms under the classical wiretap channel model.At the same time,it also gives an adaptive quantization accuracy method to generate secret key based on the channel characteristics quantization.The main work of this article is as follows:Firstly,wireless channel physical layer secret key generation model and the general process of key generation scheme based on channel characteristics quantification are introduced.The general process includes channel measurement,channel quantification,information reconciliation and privacy amplification.The performance of physical layer secret key generation protocol can be evaluated through key mismatch rate,key generation rate,and randomness.Secondly,three classical quantization algorithms used in key generation are studied.They are CQ(Channel Quantization)algorithm CQG(Channel Quantization with Guardband)algorithm and CQA(Channel Quantization Alternating)algorithm.The basic idea and algorithm flow of the three methods are introduced respectively.Their key mismatch rate as well as key generation rate are analyzed through simulation tools.Numerical results show that CQ quantization algorithm is the simplest and the performance is relatively the worst;CQG quantization algorithm performs better than the CQ quantization algorithm;the CQA quantization algorithm has the best performance in the middle of the three quantization algorithms;The CQG quantization algorithm performs better than the CQ algorithm and is slightly inferior to the CQA algorithm.However,considering the complexity and taking into account the performance of the algorithm,this thesis will focus on the CQG quantization algorithm.In the end,a complete key generation scheme is given.Firstly,an improved CQG algorithm is proposed to better the efficiency of secret key generation.It takes advantage of that adjacent codewords have only one different bit in Gray code.It sacrifices a little key mismatch rate to increase key generation rate.Then,the CQG algorithm is optimized by giving the expression for determining the value of the number of quantization intervals,which is an important parameter for determining the quantization precision in the CQG algorithm,through theoretical analysis of information theory.The performance of key mismatch rate as well as key generation rate of the improved scheme is analyzed through numeral simulation.Using CASCADE information reconciliation algorithm,both parties of legal communication can obtain a completely identical secret key.The secret keys generated by the scheme pass most of randomness test provided by NIST statistical test suite.The experimental results show that the performance of the improved CQG quantization algorithm is obvious.