Research On Physical Layer Secret Key Generation Technology For Correlated Eavesdropping Channels

The physical layer key generation technique aims to generate a consistent security key between the sender and the receiver by utilizing the time-varying,reciprocity and spatial uniqueness of the wireless channel.Spatial uniqueness means that when the distance between two channels exceeds half a wavelength,the channel characteristics are unique and irrelevant,which ensures the security performance of the physical layer key.However,in the actual communication scenario,due to factors such as user location and spatial scattering environment,the eavesdropping channel may still be related to the legal channel when the distance exceeds half a wavelength.In addition,in some scenarios,an eavesdropper has conditions for eavesdropping in the vicinity of a legitimate user,thereby reducing the security performance of the physical layer key and increasing the risk of the key being compromised.At present,scholars at home and abroad have established a system model related to the eavesdropping channel and the legal channel,and analyzed the impact of the eavesdropping channel correlation on the key capacity,but still lack the physical layer key generation scheme for the scenario.Specifically,the following two aspects are mainly involved: 1)The existing channel feature extraction method does not consider that the eavesdropper can extract channel characteristics related to the legal channel from the eavesdropping channel,resulting in a decrease in key capacity;2)The existing channel feature quantization algorithm ignores the correlation of the relevant eavesdrop channel feature quantization and the legal user generated key is similar,resulting in an increased risk of the key being compromised.Aiming at the above problems,this paper establishes a physical layer key generation model for the relevant eavesdropping channel,analyzes the impact of the relevant eavesdropping channel on the security performance of the physical layer key generation scheme,and separately targets the existing channel feature extraction methods in the SISO system and the MISO system.The problem that the eavesdropper extracts the channel characteristics related to the legal channel from the eavesdropping channel is not considered,resulting in the problem of the key capacity being reduced,and the corresponding key generation scheme is proposed.The existing channel feature quantization algorithm ignores the related eavesdropping channel feature quantization.The post-required sequence is similar to the legitimate user-generated key,which leads to the problem that the key is compromised.A key generation scheme based on double-layer decorrelation quantification is proposed.The specific research contents include:1.A key generation scheme based on secure channel estimation is proposed.The legal communication parties replace the public pilot with the real-time generated random pilot,and then use the loopback transmission method to extract the channel characteristics from the random pilot signal,and finally the extracted channel features are multi-bit adaptively quantized and the Winnow algorithm is negotiated to generate a key.The simulation results show that the scheme can make the eavesdropper unable to extract the information related to the channel characteristics of the legitimate communication parties,and the key capacity is improved when the eavesdropping channel correlation is higher than 0.85.2.A key generation scheme based on correlated eavesdropping channel scrambling is proposed.The legal communication parties superimpose the artificial noise signal orthogonal to the legal channel in the signal transmitting the pilot,and interfere with the received signal of the eavesdrop while not affecting the signals received by the legitimate communication parties,and aim at increasing the key capacity to the artificial The noise power is optimized,and finally the key is generated by the vector feature and the Winnow negotiation protocol.The simulation results show that the scheme can reduce the correlation between the key information extracted by the eavesdropper and the key information extracted by the legitimate communication parties,and can improve the key capacity of the system under different eavesdropping channel correlation conditions.3.A key generation scheme based on double-layer decorrelation quantification is proposed.The two sides of the legal communication have different precisions for the channel characteristic information,and are divided into two sequences according to the rough and detailed information,and the sequence containing the detailed information is used as the key generated by the scheme,and the coarse information sequence is used as the negotiation information to check the key.The simulation results show that the algorithm can improve the difference between the key generated by the eavesdropper and the legitimate user,and improve the security of the physical layer key.