Research On Physical Layer Key Based On Wireless Channel Characteristics

As a new security technology,the research of physical layer key aims to ensure the security of wireless communication.Its core idea is to generate high-speed and consistent security key based on the characteristics of wireless channel.The characteristics of wireless channel include time-varying,reciprocity and spatial uniqueness.Compared with the traditional encryption method,the physical layer key generation technology does not need to distribute and manage the key,which can achieve the absolute security in Shannon's secure communication theory.The physical layer key generation technology is divided into five stages: channel detection,preprocessing,quantization,information reconciliation and security enhancement.This paper focuses on the first three stages.The main research work and innovations are as follows:(1)The design and improvement of the scheme in the preprocessing stage.Firstly,this paper studies and analyzes the existing preprocessing schemes,including the preprocessing based on discrete cosine transform(DCT)and the preprocessing based on principal component analysis(PCA).Secondly,a preprocessing scheme based on singular value decomposition(SVD)is proposed,which effectively solves the problem that the existing preprocessing schemes sacrifice the key generation rate(KGR)to improve the key agreement rate(KAR).Then,an adaptive preprocessing scheme based on K-means clustering is proposed.The K-means clustering algorithm is used to improve the preprocessing scheme,and three adaptive preprocessing schemes DCT-K,PCA-K and SVD-K are obtained.Compared with the original scheme,KAR is further improved.Finally,the performance of each preprocessing scheme,including KAR,KGR and key randomness(KA),is compared and analyzed by simulation.The results show the superiority of the proposed schemes.(2)A two-dimensional cyclic quantization key generation scheme based on private pilot is proposed.First of all,this paper studies the public pilot(PP)channel detection protocol,aiming at its inability to adapt to the damaged or nonreciprocal channel,as well as its inability to resist adjacent eavesdropping attacks and other issues,and proposes a nonreciprocal random pilot(NRRP)channel detection protocol.The feasibility and security of NRRP channel detection protocol are demonstrated by theoretical analysis and verified by simulation.Secondly,the existing quantitative scheme is studied.To solve the problem that the current quantization scheme can not make full use of channel information,a quantization scheme based on two-dimensional channel parameters is proposed,and the KAR is improved by using amplitude and phase as key sources.Thirdly,aiming at the mutual restriction between KAR and KGR,a two-dimensional cyclic quantization(TDCQ)scheme is proposed.Through the cyclic coding of the initial sequence after single bit quantization,the KAR and KGR are improved.Finally,the whole scheme of key generation based on two-dimensional cyclic quantization of private pilot is proposed,and the simulation of the whole scheme shows its feasibility and superiority.