Hardware Design And Implementation For Anti-eavesdropping System Of Computer Video Information

This paper discusses the working principle of crucial components of computer video system. The sources of electromagnetic information leak from a computer video system were divided in areas, and the scheme of combination of "shielding partly" and "restraining leak sources" was brought forward. In the aspect of shielding, the characteristics of radiation of components to be shield and materials of shielding were analyzed, insuring the reliability of the shielding areas and the shielding performances. In the aspect of digital signal processing, a hardware card based on FPGA was designed, satisfying the demand of high sampling rate, high volumes of data and high data transmission rate.The "specimen computer against electromagnetic leak for computer video signal" fulfilled by our work mainly included three parts:shielding partly for host for restraining video signal leak from display card, shielding of video cable and its interfaces for restraining the video signal leak from video channel, the video signal processing card designed for lower the video signal leak from the display. It showed that the "specimen computer" was able to restrain the signal leak from a computer video system by our test.The "specimen computer" solves the intrinsic real-time difficulties problem during using software suppression simply. It overcomes the shortcomings such as high cost, bad efficiency, electromagnetic pollution when using routine TEMPEST design methods, and puts forward a new method in order to suppress the video information leakage.