ACOUSTIC CRYPTANALYSIS OF LIQUID CRYSTAL MONITORS

Abstract

This work is devoted to studying the possibilities of using acoustic cryptanalysis methods for image recognition on a liquid crystal monitor. In particular, it checks the possibility of detecting acoustic leakage of the monitor outside the studio environment using a smartphone. To do this, we simultaneously recorded sounds made by the monitor when a window was opened on the entire screen with automatically generated content simultaneously from the studio microphone and from the smartphone. The recordings were converted into spectrograms, based on a graphic analysis of which it was concluded that the LCD monitors do indeed produce a sound dependent on the content displayed on them, which can be recorded in the home environment, without the help of special equipment, and even with just a simple and typical microphone in a mobile device. Also, software was developed to generate images that most clearly demonstrate the presence of acoustic leakage in the monitor, regardless of its resolution, and also speeds up the process of collecting samples of this acoustic leak for further analysis.