A Novel Remote Visualization of Screen Images Against High-Resolution Display With Divided Screens Focusing on the Difference of Transfer Function of Multiple Emanations

Electromagnetic (EM) remote visualization of screen images attacks (RVSIAs) is among the most actively researched topics in hardware security. Target displays are being developed daily; for example, recently developed high-resolution displays have multiple divided areas on the screen, and each area transmits different pixel information. In this case, it is difficult to reconstruct the screen using the conventional methods because the target screen information is leaked by multiple lines at the same frequency and timing, and multiple screen information is mixed into the EM waves. By contrast, in this article, we propose a novel RVSIA method that focuses on the difference in the transfer functions of multiple emanations from a high-resolution display. Considering the structure and signal transmission method of recent high-resolution displays, the proposed attack method observes leaked EM waves from multiple observation positions and alters the receiving frequencies of the receiver. For the first time, we have been able to separate multiple screen information contained in leaked EM waves using an independent component analysis method. In the experiments, we applied the proposed method to an actual laptop PC that divides the screen into multiple areas. As a result, it was possible to reconstruct screen information using the proposed attack method. Thus, the proposed method enables successful attacks against recent high-resolution displays. Furthermore, the measurement equipment employed remains similar to those utilized in the conventional attacks.