键盘按键信息辐射泄漏研究

摘要

Compromising radiation emanation may appear very far away from keyboard and be detected covertly. Modulated spurious carriers, as one kind of compromising radiation emanation, have stronger anti-interference .And the red signal can be easily get from carriers with a good signal-to-noise ratio. To recovery keyboard information clearly, the modulated spurious carriers were selected. In advance, comparison of spectrum was used to discover an interesting frequency by spectral analyzers. The carriers were acquired and demodulated on our interesting frequency based on a broadband receiver. Then an accurate method was introduced to completely restore the keystrokes. Experimental results show that this technique is very effective. Finally, according to the experimental program mentioned previously, the miniaturization and practicality of keyboard electromagnetic interceptions are discussed.%计算机键盘输入电磁辐射泄漏具有覆盖范围广、截获隐蔽性强的特点，其中辐射的调制载波红信号比起其他辐射泄漏信号抗干扰性更强、更易剥离出信噪比较好的红信号。针对键盘辐射调制载波红信号进行截获，首先使用频谱对比的方法对有用信号的频段进行初判，然后基于宽带接收机对可能存在有用信号的频段进行解调，接着将得到红信号应用还原算法实现按键信息的复现，实验结果证明了这种截获方式的有效性。最后结合实验方案进一步探讨了键盘有用信号电磁截获实用化和小型化的可行性。