INFORMATION-RELEVANT FEATURES OF UNINTENTIONAL ELECTROMAGNETIC EMANATIONS FROM A PERSONAL COMPUTER
DOI:
https://doi.org/10.28925/2663-4023.2026.34.1399Keywords:
information technology; confidential information; unintentional electromagnetic emanations; technical information leakage channel; technical information protection; video signal; information-relevant feature; electromagnetic compatibility.Abstract
The operation of any information-processing equipment gives rise to a number of unintended technical channels through which information may leak. Among the most common and potentially hazardous are channels associated with unintentional electromagnetic emanations and conducted coupling. The conventional approach to protecting information against leakage through such channels is primarily focused on detecting potentially compromising emanations and determining the conditions under which they can be exploited to obtain information. At the same time, an important task is to identify, among the various unintended signals, those features that exhibit a stable relationship with confidential data and can be intercepted by technical intelligence means. The aim of this study is to investigate information-relevant features of unintentional electromagnetic emanations generated by personal computer components in order to support information protection at information-processing facilities. The study considers unintentional electromagnetic emanations from a personal computer as a technical information leakage channel. Emanations associated with the display video path, keyboard, and USB interface are analysed. It is shown that the information relevance of an emanation is determined not by its absolute level, but by its causal dependence on the information content, its temporal and spectral structure, reproducibility, ability to propagate through radiated or conducted paths, and robustness against interference. For video signals, the principal features are associated with the pixel clock, frame scanning parameters, and TMDS symbols; for keyboards, they include signal transitions, keyboard-matrix scanning, and features associated with key-code transmission; and for USB interfaces, they include data-dependent differential transitions and the packet structure of data exchange. A generalized procedure for identifying information-relevant features is proposed. The procedure makes it possible to determine which parameters of unintentional electromagnetic emanations may potentially convey confidential information and which measurable features should be examined when assessing such emanations.
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