【作者】 李珍； 张洪欣；

【Author】 LI Zhen;ZHANG Hong-xin;School of Electronic Engineering,Beijing University of Posts and Telecommunications;

【机构】 北京邮电大学电子工程学院；

【摘要】 计算机键盘用信号电磁截获的传统方法是基于宽带接收机完成的,这种方法较复杂且需要较多的设备和空间。为使键盘截获技术真正实现小型化和实用化,提出了使用基于软件无线电的解码技术及基于FPGA的截获识别平台。首先,分析了键盘产生伴随电磁辐射的机理。其次,用实验的方法在近场截获了键盘的按键信息。最后,介绍了一种能够精确判别按键信息的解码方法,通过预先设计的程序来实现信息的截获和识别。实验结果表明计算机键盘有用信号电磁截获实现实用化和小型化是可行性的,并且能够得到比较精确的结果。更多还原

【Abstract】 The general technique based on a wide-band receiver may be complicated and need more devices and space.To make this technique for miniaturization and practicability,a new decoding technique based on software defined radio and interception based on FPGA platform arc represented.In advance,the principle of radiating EM waves from keyboard unintentionally is analyzed and the time domain characteristics of leak signal are studied.Then,the keystrokes are recovered in the near-field through the experiment.Finally,this paper introduces an accurate method to completely recover the keystrokes,and then get the result using prc-dcsign software.Experimental results show that the miniaturization and practicality of PS/2 keyboard electromagnetic interceptions arc feasible,and the result is also precise.更多还原