Countermeasure for electromagnetic screen image leakage based on color mixing in human brain

The security problem of screen image leakage from a display unit has received wide interest of security researchers since the Van Eck's paper. As for the industry side, the problem is considered a security risk; especially for the computers that are used in the sensitive business fields, i.e. banking, data center. To solve this problem, reduction of the emanating signals' S/N ratio is important. Therefore, signal reduction and noise generation methods have been investigated as countermeasure. We present a method that imposes noise on displayed screen images, while keeping the quality of the image. This is realized by utilizing the human characteristic that is known as “Additive color mixing”, which occurs when the eyes are continuously exposed to quickly changing colors. By implementing this method on hardware and software in an ordinary computer system, we confirmed the effectiveness of our method as a countermeasure for the electromagnetic screen image leakage.