研究目的
Investigating a novel technique for data transmission from air-gap secured computers using backlight modulation of the screen, which is invisible to humans but can be captured and demodulated using a digital camera and telescope.
研究成果
The proposed technique is efficient for small data sizes transmission at moderated distances, valuable for transmitting sensitive information from air-gap secured systems without requiring special privileges. Future work will focus on estimating the attack's dependency on light conditions.
研究不足
The effective transmission speed is very low, optimal at 0.25 bps, making it suitable only for small data sizes like passwords or PINs. Environmental conditions can influence the process, and the technique requires the monitor to be turned on and is disturbed by user activity.
1：Experimental Design and Method Selection:
The study employs BFSK modulation for data transmission via screen backlight modulation, invisible to humans but detectable by digital cameras.
2：Sample Selection and Data Sources:
Tests were conducted with different configurations of data transmission parameters and acquisition hardware, including a cheap webcam and a digital camera attached to a telescope.
3：List of Experimental Equipment and Materials:
Titanum TC102 webcam, OLYMPUS SZ-11 digital camera, and a 36050 Telescope.
4：Experimental Procedures and Operational Workflow:
The process involves signal generation via BASH script, signal acquisition through camera observation, and signal demodulation using Matlab for off-line processing.
5：Data Analysis Methods:
The demodulation scheme includes reading the input video file, removing constant signal and noise, estimating center frequencies, band-pass filtering, envelope detection, and binary stream recovery.
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