TEMPEST Font Protects Text Data against RF Electromagnetic Attack

Abstract

Nowadays an electromagnetic penetration process of electronic devices has a big significance. Processed information in electronic form could be protected in different ways. Very often used methods limit the levels of valuable emissions. But such methods could not always be implemented in commercial devices. A new solution (soft tempest) is proposed. The solution is based on TEMPEST font. The font does not possess distinctive features. This phenomenon causes that at an output of Side Channel Attack the possibilities of recognition of each character which appears on the reconstructed image for sources in the form of graphic lines (VGA and DVI) are limited. In this way the TEMPEST font protects processed data against electromagnetic penetration not only for VGA and DVI standards. The data are protected during printing them on laser printers too.