EMC ’ 09 / Kyoto Countermeasure Technique for Preventing Information Leakage Caused by Unintentional PC Display Emanations

A working personal computer (PC) and/or a PC display monitor usually produce unintentional electromagnetic fields. It has been known that the information from a video display unit could be reconstructed by intercepting such emissions at a distance. Proper measures are needed to prevent information leakage against such eavesdropping, which are often collectively called “TEMPEST”. We have studied a countermeasure technique for such a problem and proposed jamming schemes for industrial and home use. We also developed a prototype for protecting devices and evaluated its performance in preventing such emanation eavesdropping.