Analysis And Reconstruction Of LCD Electromagnetic Information Leakage Based On Power Line

With the further development of information technology in e-commerce,e-government and military equipment,information security problems caused by electromagnetic information leakage has become increasingly prominent.In the normal working process,the computer host and its display system will generate electromagnetic information leakage through the power supply network,causing the sensitive information to be intercepted and reappeared,which poses a serious threat to the security of electromagnetic information.The power line is the best way to intercept the information of the public network.It is of great significance to study the detection of the electromagnetic leakage information,the recognition and reconstruction of the red signal for the electromagnetic leakage information detection and protection of the electronic equipment.In this paper,aiming at the problem of red signal extraction and effective discrimination of the power line conduction leakage,By analyzing the video signal and the line synchronization signal,the characteristics of the video system signal are studied,the transmission characteristics of the leakage signal in the power line are deduced,the experimental interception platform of the conduction leakage signal is designed,and the test and analysis of the time domain and frequency domain are carried out.The direct detection method and statistical classification method are used to process the leakage signal,and the spectrum search method is proposed to extract the row synchronous signal and realize the reconstruction of the display image.The main work of this paper is as follows:1.The characteristics of conduction leakage signal and the basic ways of leakage are analyzed,and the mechanism of conduction leakage is revealed.According to the display principle of the display equipment,the signal representation of the video information is analyzed,and the time domain and spectrum characteristics of the video signal are deduced.Combined with the principle of electromagnetic compatibility,the basic form of conduction coupling is analyzed.This paper analyzes the basic principle of power line leakage,clarifies the basic way of leakage,establishes the equivalent transmission line model of power line,and deduces the transmission characteristics of leakage signal in power line.2.Aiming at the difficulty of extracting red signal from conduction emission,a method for image reconstruction based on direct detection is proposed,the reconstruction of transmission leakage information of LCD power line is realized and the quality of reconstructed image under different SNR is analyzed by simulation.Based on the mechanism of conduction leakage,the experimental interception platform of conduction emission signal is built to collect the transmission leakage signal of power line,and the characteristics of conduction leakage signal are analyzed.The edge pulse of conduction leakage signal is extracted based on the detection of singular point in the wavelet transform and the reconstruction of video signal is realized.A row synchronization signal extraction method is proposed to reconstruct the display image of LCD display.The reconstruction rate is used to quantify the reconstructed image quality and the relationship between the reconstruction rate and the SNR is analyzed by simulation.The results show that when the SNR is greater than-6 dB,the signal reconstruction rate is higher than 90 dB.3.Aiming at the problem that it is difficult to recognize the red signal of multiple display devices connected to the same power line network,a method of image reconstruction based on statistical classification is proposed.The reconstruction of LCD transmission leakage information is realized and the prediction accuracy of different methods is compared and analyzed.According to the corresponding relation between jump edge of trapezoidal video signal and pulse of leakage signal,a training model is established by means of statistical learning,and the edge signal is recognized by the training model based on prior knowledge.In order to verify the effect of the algorithm on the leakage signal processing of a single device,PSO-SVM is used to train and classify the conductive leakage signal,and the classification performance is compared with that of the SVM classification.The results show that the accuracy of classification and prediction is improved obviously after PSO optimization of SVM classifier,reaching 95%.In order to prove the efficiency of red signal recognition by this algorithm when multiple display devices are connected to the same power network,the leakage signals of two display devices connected to the same power supply network are collected,and the leakage signals are trained and classified by PSO-SVM.The results show that the algorithm not only handles the leakage signal of a single display device well,but also has a high accuracy rate for the classification of the leakage signals of the two display devices,reaching 80%.