Electromagnetic Eavesdropping on DisplayPort

Authors:
Open Access
Publisher website
Google Scholar
Abstract
Radiated electromagnetic emissions from video cables can leak information about the displayed image content to radio receivers in the vicinity. This confidentiality risk has long been demonstrated for analog video interfaces, such as VGA, as well as certain digital interfaces, such as DVI, HDMI, and the LVDS video connections often used inside devices with display panels. In all these cases, rasterizing amplitude-demodulated radio signals received in a quiet part of the spectrum can lead to recognizable screen content and readable text. However, DisplayPort, another commonly used computer video interface, has so far resisted such eavesdropping attacks. DisplayPort's significantly more complex signal structure and line encoding, and in particular its use of a linear-feedback shift register to scramble the bit stream, make its rasterized emissions appear like noise after amplitude demodulation. Here, we demonstrate more sophisticated video eavesdropping techniques for DisplayPort emissions, based on software-defined radio technology. These allow us to identify the video-mode parameters used by the target and synchronize the receiver with its timing structure, to then reconstruct not only readable text but also recognize different colours used. Our techniques work even if the receiver's bandwidth is an order of magnitude lower than the bitrate used on the video link.

This publication has 12 references indexed in Scilit: