Probability Distributions.- Linear Models for Regression.- Linear Models for Classification.- Neural Networks.- Kernel Methods.- Sparse Kernel Machines.- Graphical Models.- Mixture Models and EM.- Approximate Inference.- Sampling Methods.- Continuous Latent Variables.- Sequential Data.- Combining Models.

Pattern Recognition and Machine Learning

This paper focuses on the compromising video emanations from a desktop computer with a liquid-crystal display (LCD). Near-field tests are performed in a common unshielded office environment to investigate the video information leakage, and the tests show that the video graphics adapter (VGA) connector is a leaking source. To illustrate the mechanism of the video leakage, a wire antenna model is developed according to the physical dimensions of the connector. The radiated fields of the connector are calculated in the time domain from this model, the results are verified by the tests. Combining the expressions of the radiated fields and the transfer function of the test probe, the function relationship between the original red/green/blue signal and the intercepted signal is established. Finally, a readable text is reconstructed from the intercepted signal when a Chinese document is displayed on the LCD.

Investigation of Unintentional Video Emanations From a VGA Connector in the Desktop Computers

While operating, information processing devices or communication systems may emit unwanted signals (or alter existing ones) through electromagnetic waves, light, sound or power drain. These side-channels can be intercepted by anyone with scientific or technical knowledge and appropriate equipment, leading to a potentially high risk of security breaches. This survey focuses on these emanation side-channels and provides an extensive literature review. To provide an in-depth analysis despite the variety of attacks, we propose to classify the side-channels based on their intentionality, the type of attackers and the physical medium. Illustrative use-cases are presented and serve as a basis to infer individual threats. Particular attention is paid to electromagnetic side-channels which exhibit the highest criticality and have therefore been used in the most recent attacks. The main characteristics of the side-channels revealed by state-of-the-art papers are summarized, and recommendations on countermeasures are provided to protect any sensitive equipment.

/pdf/whispering-devices-a-survey-on-how-side-channels-lead-to-4l78c9g7g8.pdf

Whispering devices: A survey on how side-channels lead to compromised information

This paper proposes a method that reconstructs the original video data signal from leaking electromagnetic emanations of multiple video signal sources using a software-defined radio (SDR). The results of the method give valuable insights into the potential risk of this threat of obtaining sensitive information in an everyday situation. The leaking emanations of co-located identical high definition liquid crystal displays are analyzed for possible data reconstruction using a SDR of a small form factor. It is proven that the leaked emanations of multiple identical active video display units (VDUs) can be separated from each other and that their separate video images can be reconstructed individually from one data acquisition. Moreover, this is done by recovering the synchronization frequencies and the image resolution by exploiting multiple leakage channels without having any foreknowledge of the VDU's properties. A multitude of leakage channels is investigated and analyzed for their radiation pattern and their signal-to-noise ratio, and is exploited to increase the quality of the reconstructed images employing multiple-input multiple-output based techniques. As far as we can see, our results and new insights in the nature and mechanisms of multiple compromising emanations are crucial for improving video data security.

/pdf/a-quantitative-approach-to-eavesdrop-video-display-systems-4fjsz7jup5.pdf

A Quantitative Approach to Eavesdrop Video Display Systems Exploiting Multiple Electromagnetic Leakage Channels

In this paper a method is presented which successfully reconstructs the video image of a video display unit (VDU) by exploiting its leakage emissions at a distance of 80 meters. The video image reconstruction is realized without any prior knowledge of the leaking VDU and by using commercial off-the-shelf material. The tested VDUs comprise of an UHD (ultra-high-definition) video display and a full HD (high-definition) video display, both employing an HDMI (high-definition multimedia interface) cable as a video data signaling interface linked to a notebook. The tested setups are located in an urban environment with sporadic radio emissions and occupied frequency bands. Subsequently, the methods and results are thoroughly discussed which give new insights into this video eavesdropping risk for improving video data security.

Eavesdropping a (Ultra-)High-Definition Video Display from an 80 Meter Distance Under Realistic Circumstances

Increasing speed of digital equipment moves the electromagnetic compatibility (EMC) studies into a new point due to their broadband radiated emission characteristics. Beside preventing interception from electromagnetic radiation, it is desirable to identify the information source from the radiated emissions. In this paper, we analyzed the sources of the differences among LCD emanations by checking main circuits of computer LCD. A cyclic spectrum identification (CSI) algorithm has been developed to realize the individual recognition of computer LCDs through compromising emanations. We extracted the features of computer LCD emanations in the cycle frequency domain. This work focuses on recognizing the computer LCDs automatically and accurately without reconstruction of the display images. The performance of the CSI algorithm is evaluated by applying it to experimental data collected in a practical attack scenario.

Computer LCD recognition based on the compromising emanations in cyclic frequency domain

Video leaking signal detection is an important part of TEMPEST, which is the technologies research focus on the investigations and studies of compromising emanations. A novel video leaking signal detection algorithm based on spectral centroid has been developed. Using the property that spectral centroid can accurately identify the signal energy center in frequency domain, the proposed algorithm can detect the display video leaking signal automatically. The uniformity degree of spectral centroid spacing distribution is defined to distinguish the video leaking signal and clutter signal automatically. Furthermore, the ant-jamming and ant-noise performance of the developed algorithm is analyzed in a practical attack scenario.

A novel method for computer video leaking signal detection

Confidential information might be leaked through electro-magnetic radiation from a computer display. To detect the electromagnetic radiation that contains text information, this paper proposed an evaluation method without reconstructing the displayed image. In this method, sparse decomposition in wavelet is used to describe the characteristics of electromagnetic radiation signals contain text information. By using this method, it is easy to detect text information leakage in electromagnetic radiation from a computer display.

/pdf/method-for-determining-whether-or-not-text-information-is-1xi5u267lw.pdf

Method for Determining Whether or not Text Information Is Leaked from Computer Display Through Electromagnetic Radiation

Information might be leaked through electromagnetic radiation from a computer display. Radiation containing information and radiation without information should be treated differently. Therefore, a novel algorithm has been developed to determine whether or not information is leaked in electromagnetic radiation. Motivated by the observation that the Gabor coefficients of information part and the non-information part of reconstructed image follow different statistical distribution, we propose a method to describe these differences and detect information leakage. In this method, probability graph theory is used and the probability mean distance is defined. In addition, the detection rule is set to realize automatic detection of information. By using this method, we can accurately and efficiently detect the information leakage in electromagnetic radiation from a computer display.

Method for Detecting Information Leakage from Computer Display in Electromagnetic Radiation

Electromagnetic radiation signal from computer display can be seen as a computer security risk if the radiation signal is intercepted and reconstructed. Electromagnetic radiation signal from computer display can also be called video leaking signal. Synchronising information extraction is the key problem of computer video leaking signal interception and reconstruction. To solve such problem, a novel synchronising information extraction algorithm based on spectral centroid has been developed. This study not only introduced spectral centroid into video leaking signal processing but also defined the concept of segmented spectral centroid. In addition, the uniformity degree of spectral centroid spacing distribution was defined to describe the harmonic characteristics of video leaking signal spectrum. The proposed algorithm can extract the electromagnetic radiation signal's synchronising information automatically and efficiently even with interference signal. Thus, the interception and reconstruction of electromagnetic radiation can be realised more effectively and the anti-interference performance can be improved.

https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/iet-spr.2014.0508

Efficient and anti-interference method of synchronising information extraction for cideo leaking signal

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