Differential Signaling Compromises Video Information Security Through AM and FM Leakage Emissions

Abstract

Video display units (VDUs) using differential signaling technology significantly increase the risk of compromising video information security through leakage emissions. This paper shows that differential signaling cables act as substantial video leakage sources. A concept is proposed which explains the video leakage principles of VDUs using differential signal cables such as the HDMI (high-definition multimedia interface) cable, DVI (digital visual interface) cable and the LVDS (low-voltage differential signaling) cable. The emanations of the LVDS cable are closely examined by measuring simultaneously the differential video signal on the LVDS lines and its near-and far-field leakage emissions. From these measurements several conclusions are drawn which give new insights into the video eavesdropping risk of VDUs using differential signaling methods. Furthermore, a novel video image reconstruction method is proposed which exploits the compromising emanations of a video display unit (VDU) by using frequency demodulation techniques. This paper shows that leaked video emanations of VDUs using differential signaling cables are not only amplitude modulated (AM) but also frequency modulated (FM). This strongly implies that the possible algorithmic toolset of malicious video eavesdroppers is much larger than currently assumed. This paper investigates several VDU setups at a distance of 10 meters, including an ultra-high-definition video display, three different HDMI cables and two notebooks. Additionally, the AM-based and FM-based video image reconstruction results are discussed and compared.

A Quantitative Analysis of Compromising Emanation from HDMI and Possibility of Information Reconstruction

“…These articles are well-organized based on individual experimental results; however, a majority of them ignore the intuitive relationship between the electronic signal, including the display information, and the EM leakage from the perspective of radio communication. Moreover, when it comes to the frame-averaging scheme, which is commonly utilized to reduce intense noise included in the CE [8], [11], [15], most prior studies have only described the results. A quantitative analysis of the possibility of information reconstruction according to frame-averaging has rarely been discussed.…”

“…7, according to its subscript color. The EM leakage appears in a broad frequency band; thus, if a particular band including a specific harmonic component of the respective pixel can be collected among the multiple configurations, it is possible to distinguish the difference in pixel values using various demodulation methods [15]. Here, for the band-limited signal collection, a real-time SDR comprising down-conversion, filters, and a continuous signal sampler can be utilized, as shown in Fig.…”

“…Here, for the band-limited signal collection, a real-time SDR comprising down-conversion, filters, and a continuous signal sampler can be utilized, as shown in Fig. 8, [15], [16].…”

“…However, in a realistic environment, the CE is combined with noise, the distribution of which follows the Gaussian. Hence, S noisy that comprises S f r , and N AW GN is newly introduced in the analysis as in ( 14) and its SNR can be defined as in (15).…”

A Quantitative Analysis of Compromising Emanation From TMDS Interface and Possibility of Sensitive Information Leakage

“…These articles are wellorganized based on individual experimental results; however, most of them do not consider the intuitive and mathematical relationship between the electronic signal, including the display information, and the EM leakages from the perspective of radio communication. Moreover, when it comes to the frame-averaging scheme, which is commonly utilized to overcome intense noise included in the compromising emanation (CE) [8], [11], [15], most of the previous studies have only described final results. A quantitative analysis of the possibility of information reconstruction in conjunction with the frame-averaging has rarely been discussed.…”