Research On Key Generation Method Based On Physical Layer Characteristics Of Wireless Channel

With the rapid development of science and technology and the rapid increase of computing speed,the communication key system based on cryptosystem has been greatly threatened.Although it is possible to increase the security of the key by adding a key length,it does not guarantee complete security and consumes too much power.Different from the traditional communication encryption technology,the key generation method based on the characteristics of the wireless physical layer starts from the physical layer characteristics,and the dynamic key can effectively ensure the security of communication.In recent years,it has become the focus of research by scholars at home and abroad.This paper studies the security key generation of wireless communication physical layer.The main work of this paper is as follows:1.Aiming at the problem that the physical layer quantifies the key mismatch rate,a non-uniform quantization scheme is proposed.In the wireless physical layer key extraction process,due to additive noise,half-duplex nature of the wireless channel,and device variability,the actual channel is not reciprocal,and there is a key mismatch rate in the key generation process.Under the specified wireless signal strength Gaussian distribution model,the existing uniform quantization method is analyzed by numerical calculation,and the theoretically uniformly quantized key mismatch rate is derived.It is concluded that uniform quantization is the highest key mismatch rate of Quantitative method.In this paper,a non-uniform quantization method is proposed.According to the joint probability density of the two communicating parties,the corresponding key mismatch rate is calculated according to the correlation coefficient.The actual measurement and simulation results show that the proposed quantization scheme can effectively reduce the key mismatch rate in the wireless communication process and improve the reliability of the shared key.2.Due to noise,hardware and other non-reciprocity factors,the points around the quantization threshold will fall into different quantization intervals,resulting in inconsistent key sequences.To solve this problem,this paper proposes a non-uniform quantization method with protective band,which retains the channel information in the quantized protective band and eliminates the channel information outside the protective band.The legal communication parties obtain the position information that needs to be quantized together by interacting with the position corrector.From the simulation results,we can see that when the correlation coefficient is high,the quantization scheme with the protection band has better performance in reducing the key mismatch rate.3.Aiming at the potential threat of excessive key leakage in the information coordination scheme in the physical layer key generation process,this paper proposes a BCH encoding key agreement scheme based on encryption algorithm.After the legal communication parties generate the initial key sequence,key negotiation is performed to correct the partial error code.However,there is no protection in the process of information interaction,and the key is very likely to leak.The process based on the encryption algorithm can ensure the security of the key in the process of information interaction as long as the algorithm is not cracked in the coherent time.In this way,the error code is corrected and the security is ensured in the process of information coordination.