Electromagnetic Eavesdropping

Protection of information against electromagnetic penetration is a huge challenge. Especially this issue applies to computer station that processes protected information and that is a source of electromagnetic disturbances. These disturbances could be correlated with processed graphic information. Therefore, very often, they are called valuable or unintentional emissions. To protect the information, different methods of engineering of electromagnetic compatibility are used, e.g. electromagnetic gaskets, signal and power filters and electromagnetic shielding. The use of these methods causes a special device to become very heavy, and the looks of such device aren’t nice. A new universal solution based on safe fonts is proposed. Safe fonts protect processed information against electromagnetic penetration in each case of graphic source of valuable emissions. These fonts protect not only Video Graphics Array (VGA) but also Digital Video Interface (DVI) standards. These fonts are also useful from electromagnetic protection’s point of view in the case of the use of laser printers. All analyses are based on images reconstructed from valuable emissions. These emissions are measured in a range of frequencies from 100 MHz to 1.5 GHz. Safe fonts are simple solution that counteract electromagnetic eavesdropping process. They can replace expensive solutions based on shielding, zoning and filtering

누설전자파를 위한 방사 보안 레벨 및 신호 복원

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2013. 8. 김성철.In this dissertation, reconstruction of electromagnetic emanation security (EMSEC)-channel information for video display units and printer are reconstructed using the averaging technique and proposed adaptive deringing filter. Also, emission security limits are proposed based on the analysis of the indoor EMSEC-channel. An emitted waveform from equipment which manages the important information can be detected and restored intentionally using the sensitive antenna and high performance receiver. These documents related to the EMSEC have classified by high confidentiality so that these are prohibited to publish by military organization. For this reason, reasonable emission security limits for various electronic devices dealing with significant information are necessary. Firstly, we try to identify the exact a signal characteristics and the frequency components to measure and analyze the spectrum of electromagnetic waves which are contained information on personal computer (PC) and printer. The target devices are the desktop, laptop and laser printer which is generally used in the domestic offices in this study. The printer processed a large amount of information for a short period of time, there may be leaked the information in this process. To verify the leakage of electromagnetic spectrum that contains information, we measure and analyze the whole spectrum from 100 MHz to 1000 MHz. Secondly, we represent how to build the EMSEC-system and to restore the signal leakage of electromagnetic waves on the basis of the signal characteristics of the electromagnetic wave leakage of printer and video display unit (VDU) of PC. The parameters that can improve the performance of signal recovery of the leakage electromagnetic wave, it can be given antenna sensitivity, resolution bandwidth (RBW) of the receiver, and signal processing gain. To adjust the signal processing gain, antenna which have the high antenna gain, and the use of wider RBW on receiver are improved hardware of EMSEC system. Whereas image restoration algorithm for EMSEC system as post-processing is a portion corresponding to the software of EMSEC system. Techniques for increasing signal strength and noise reduction are particularly important when trying to measure compromising emanations because the magnitude of these signals can be extremely small. Averaging technique find to achieve maximum cross correlation between recorded electromagnetic leaked signals. That method is a practical, highly effective and widely used technique for increasing the signal-to-noise ratio (SNR) of a periodic signal, such as that generated by the image-refresh circuitry in a video display system. But, the printer and facsimile exhibit aperiodicity in their EMSEC-channel information during their operation state unlike video display systems. Since the aperiodic EMSEC-channel information of equipments such as printers and faxes is not involved in processing gain, the differences between periodic- and aperiodic compromising emanations need to be considered in order to establish emission security limits. In addition to, we propose the adaptive deringing filter to reconstruct the EMSEC- channel information from PC and printer. We can obtain that the minimum peak signal-to-noise ratio (PSNR) enhancement is 2 and maximum PSNR enhancement is 10 compared with the original reconstructed image. Next, we perform the EMSEC-channel measurements in the 100?1000 MHz frequency bands. Second, we analyze the pathloss characteristics of the indoor EMSEC-channel based on these measurements. We find the frequency correlation pathloss characteristics of compromising emanations to determine the reasonable total radio attenuation (TRA). Also, the pathloss exponent value have a range from 1.06 to 2.94 depending on frequency band and the CMs, which in turn differed with propagation environments. Through this EMSEC-channel analysis, we affirm that the TRA, which is one of the key parameters for determining the security limits for compromising emanations, follows the Rician distribution. However, previous work assumed that radio attenuations would have constant values. We found that the TRA does not show significant differences depending on the frequency bands and has the following range depending on the environment, 29?41dB at CM2, a 42?57 dB at CM3, a 47?57 dB at CM4, and 24?29 at CM5. In addition to, CM3 and CM4 have greater TRA than CM2 and CM5. Based on the experimental results of this study, we propose security limits on periodic as well as aperiodic EMSEC-channel information. The proposed security limits on compromising emanations are classified into two levels according to the TRA and the level of required confidentiality. Periodic emission security limits for class A is 24, 28, 35 dBμV/m in the 100-400 MHz, 400-900 MHz and 900-1000 MHz, respectively. And periodic emission security limits for class B is 4, 1, 3, 5 dBμV/m in the 100-200 MHz, 200-600 MHz, 600-700 MHz and 700-1000 MHz, respectively. Aperiodic emission security limits are weaker than the processing gain Gp, 23 dBi than periodic emission security limits owing to the redundancy caused by repetitive signals. So, that the periodic EMSEC-channel information is easily leaked and reconstructed, which results in a potential risk. Thus, the periodic emission security limits must be stronger than the aperiodic emission security limits. We can then compare our security limits with other security limits and existing civil and military EMC standards. Future works may include characterization and reconstruction of FAX, smartcard and other electronics. And it is need to EMSEC-channel analysis in more complex environments.Chapter 1 Introduction.............................................................1 1.1 Historic background and previous work......................................3 1.2 Motivation and scope...................................................................6 Chapter 2 Detection of Compromising Emanations................9 2.1 Introduction..................................................................................9 2.2 Compromising Emanations from Video Display Units.............10 2.2.1 Property of Video Display Units ..............................................10 2.2.2 Leakage path of Video Display Units........................................11 2.2.3Measurement system...................................................................13 2.2.4 Measurement result....................................................................15 2.3 Compromising Emanations from Printer...................................17 2.3.1 Property of Printer.....................................................................17 2.3.2 Leakage path of Printer..............................................................19 2.3.3 Measurement system..................................................................20 2.3.4 Measurement result....................................................................21 2.4 Conclusion..................................................................................23 Chapter 3 Reconstruction of Compromising Emanations.....25 3.1 Introduction................................................................................25 3.2 EMSEC system for Reconstruction...........................................26 3.3 Reconstruction of Compromising Emanations from Video Display Units....................................................................................26 3.3.1 Characteristics of EMSEC-channel information from VDUs...26 3.3.2 Reconstruction result.................................................................30 3.4 Reconstruction of Compromising Emanations from Printer… 31 3.4.1 Characteristics of EMSEC-channel information from Printer..31 3.4.2 Reconstruction result.................................................................34 3.5 Adaptive Deringing Filter for EMSEC-channel information Reconstruction..................................................................................36 3.6 Conclusion..................................................................................40 Chapter 4 Characteristic of Frequency Correlation EMSEC-Channel in indoor environments............................................42 4.1 Introduction................................................................................42 4.2 Measurement methodology........................................................43 4.2.1 Measurement system..................................................................43 4.2.2 Measurement scenario and environment...................................43 4.3 Analysis of indoor EMSEC-Channel for Compromising Emanations…………………………………..................................46 4.3.1 Frequency correlation property of indoor EMSEC-Channel....47 4.3.2 Pathloss characteristics of indoor EMSEC-Channel.................52 4.4 Conclusion..................................................................................56 Chapter 5 Emission Security Limits for Compromising Emanations.............................................................................58 5.1 Introduction................................................................................58 5.2 Parameters for Emission Security Limits …………………….58 5.2.1 Total radio attenuation...............................................................60 5.2.2 Radio noise.................................................................................65 5.2.3 Antenna gain..............................................................................67 5.2.4 Signal processing gain...............................................................68 5.2.5 Minimum SNR for reconstruction.............................................69 5.2.6 Receiver noise figure.................................................................70 5.2.7 Calculation of emission security limits.....................................71 5.3 Proposed Emission Security Limits...........................................72 5.4 Comparison with Public Standards and Other Security Limits.75 5.4.1 CISPR 22 and MIL-STD-461E.................................................75 5.4.2 Security limits for Markus Kuhn...............................................76 5.4.3 ITU-T K.84 Guidelines..............................................................78 5.5 Conclusion..................................................................................84 Chapter 6 Summary and Further Study.................................86 Bibliography 90 Abstract in Korean.................................................................95Docto

Development of a Handheld Scanning Transducer Probe for Ultrasound Imaging

The scanning transducer technique is a simple and cost effective approach to achieve ultrasound imaging. By mechanically scanning a single-element transducer with a motor stage, the time-variant ultrasound field at an array of locations can be recorded for image reconstruction. When compared with the use of conventional transducer arrays, the scanning transducer approach requires much less data acquisition electronics. However, conventional x-y motor stages used for scanning the transducer are complex, bulky and slow. As a result, the scanning transducer technique for image acquisition has been mainly limited for lab use and is not suitable for handheld imaging applications. The goal of this research is to achieve a new 2-axis scanning transducer probe for handheld ultrasound imaging operations, which is compact and light-weight. The approach is to develop and capitalize upon a miniaturized water-immersible 2-axis electromagnetic actuator to enable fast and agile scanning of a single-element transducer in a liquid filled probe case. The design and fabrication of a water-immersible 2-axis electromagnetic actuator has been achieved and its mechanical scanning performance has been characterized and optimized with finite-element simulation. Preliminary pulse-echo imaging experiments were performed to verify its ultrasound imaging capability with scanning in B-scan mode in multiple directions. The scan system built can be dynamically reconfigured to either 1D- B-Scan or even 2D C-Scan formats for conventional 2D as well as 3D ultrasound imaging. In addition, integrated optical light delivery with optic fiber cables was also investigated to extend its capability for photoacoustic imaging

Compact microscopy systems with non-conventional optical techniques

This work has been motivated by global efforts to decentralize high performance imaging systems through frugal engineering and expansion of 3D fabrication technologies. Typically, high resolution imaging systems are confined in clinical or laboratory environment due to the limited means of producing optical lenses on the demand. The use of lenses is an essential mean to achieve high resolution imaging, but conventional optical lenses are made using either polished glass or molded plastics. Both are suited for highly skilled craftsmen or factory level production. In the first part of this work, alternative low-cost lens-making process for generating high quality optical lenses with minimal operator training have been discussed. We evoked the use of liquid droplets to make lenses. This unconventional method relies on interfacial forces to generate curved droplets that if solidified can become convex-shaped lenses. To achieve this, we studied the droplet behaviour (Rayleigh-Plateau phenomenon) before creating a set of 3D printed tools to generate droplets. We measured and characterized the fabrication techniques to ensure reliability in lens fabrication on- demand at high throughput. Compact imaging requires a compact optical system and computing unit. So, in the next part of this work, we engineered a deconstructed microscope system for field-portable imaging. Still a core limitation of all optical lenses is the physical size of lens aperture – which limits their resolution performance, and optical aberrations – that limit their imaging quality performance. In the next part of this work, we investigated use of computational optics-based optimization approaches to conduct in situ characterization of aberrations that can be digitally removed. The computational approach we have used in this work is known as Fourier Ptychography (FP). It is an emerging computational microscopic technique that combines the use of synthetic aperture and iterative optimization algorithms, offering increased resolution, at full field-of-view (FOV) and aberration-removal. In using FP techniques, we have shown measurements of optical distortions from different lenses made from droplets only. We also, investigated the limitations of FP in aberration recovery on moldless lenses. In conclusion, this work presents new opportunities to engineer high resolution imaging system using modern 3D printing approaches. Our successful demonstration of FP techniques on moldless lenses will usher new additional applications in digital pathology or low-cost mobile health

Design and additive manufacture for flow chemistry

This thesis aims to investigate the use of additive manufacturing (AM) as a novel manufacturing process for the production of milli-scale chemical reaction systems. Five well developed additive manufacturing techniques; stereolithography (SL), selective laser melting (SLM), fused deposition modelling (FDM), ultrasonic additive manufacture (UAM) and selective laser sintering (SLS) were used to manufacture a number of miniaturised flow devices which were tested using a range of organic and inorganic reactions. SL was used to manufacture a range of functioning milli-scale flow devices from Accura 60 photoresin, with both simple and complex internal channel networks. These devices were used to perform a range of organic and inorganic reactions, including aldehyde and ketone functional group interconversions. Conversion of products within these reactors, were shown to be comparable to commercially available milli-scale coil reactors. More complex designs, which allowed SL parts to be integrated to existing flow and analytical instrumentation, allowed us to develop an automated reaction analysis and optimisation platform. This platform allowed precise control over the reaction conditions, including flow rate, temperature and reagent composition. We also designed a simplex type reaction optimisation software package that could input data in the form of reaction conversions, peak intensities, and thermocouple data, and generate a new set of optimal reaction conditions. SL parts which incorporated embedded analytical components were also manufactured, which allowed us to perform inline reaction analysis as a feedback method for input into the optimisation platform. Stereolithography was shown to be a highly versatile manufacturing method for designing and producing these flow devices, however the process was shown to be still limited by the range of processable materials currently commercially available. SLM was also used to manufacture a number of functioning milli-scale flow devices from stainless steel and titanium, which had simplistic internal channel designs of diameters ranging from 1 to 3 mm. Again, SLM parts were manufactured which incorporated embedded analytical components, which could be integrated into an automated reaction platform. These devices, unlike parts produced via SL, could be attached to heating platforms to allow us to perform high temperature reactions. This control over the reaction temperature formed an essential part of the reaction optimisation platform. These parts were again used to perform a ketone functional group interconversion. Internal structures of these SLM parts were also visualised via micro computed tomography (µCT or microCT) scanning as well as optical microscopy. FDM was used throughout the project as an inexpensive method of prototyping parts which were to be manufactured via more expensive manufacturing processes. This prototyping allowed the optimisation of intricate design features, such as the manufacture of an inline spectroscopic flow cell for integration with a commercially available LC system. FDM was also proposed as a customisable approach to designing and manufacturing flow devices with embedded components, however the current limitations in build resolution and materials choices severely limited the use of FDM for this application. UAM was also proposed as a novel manufacturing process whereby the build process would allow discrete components to be embedded directly into a flow channel. This was demonstrated by embedding a type-k thermocouple across a 2 mm channel. The data from this thermocouple was monitored during a heated reaction, and used as a method of determining the exact reaction conditions the reaction medium was being exposed to. SLS was also proposed as a possible manufacturing method for milli-scale flow devices, however it proved difficult to remove un-sintered powder from parts with internal channel diameters as high as 5 mm. It was shown that this powder was forming a dense semi solid, due to the large degree of shrinkage upon cooling of the SLS parts, which was compressing the powder. More research into optimum processing conditions is required before SLS could be used for the production of intricate channel networks

Control of additive manufacturing for radio frequency devices with spatially varying dielectric properties

Additive manufacturing (AM) is increasingly being used to fabricate end-use and high-value-added parts in a range of industries. AM’s ability to create complex geometries and vary the internal composition of a part has enabled the design of many novel devices, including radio frequency (RF) devices that rely on the spatial variation of electromagnetic (EM) properties. However, current AM processes for fabricating complex parts are typically run without any part monitoring or online feedback control, and as a result, the printed parts may be compromised by defects or have poor tolerances. Manufacturing parts in this way also requires extra quality testing since there is no knowledge of their interior quality. For these reasons, introducing process monitoring and corrective action to the AM process has become an important area of research as AM is being used to create safety-critical parts. This work proposes a control algorithm to enable closed-loop control of an EM property, specifically dielectric permittivity, within a print using a fused filament fabrication (FFF) printer. The control system used a split-ring resonator (SRR) to measure the permittivity of printed thermoplastic, and the control action was applied by updating the printed infill density layer to layer. This control system was tested by printing a proof-of-concept graded-index (GRIN) lens with spatially varying permittivity through the lens’ length. The results demonstrate the ability of the controller to follow a constantly varying reference signal, indicating the potential of closed-loop control for improved fabrication of functional RF devices that depend on precise variations in relative permittivity

Noise, artifact and the uncanny in large scale digital photographic practice.

This dissertation explores the question: why, when encountering the products of many new technologies delivering information via a new media, do I often experience a feeling of disquiet or estrangement? I use the example of laser-photographic printing to explore the issue through a program of practice-based research. The outcome of this line of enquiry includes an original contribution via three series of large-format digital photographic works: Presenting "The Amazing Kriels", Home At Last, and Pure. In this thesis, which supports the main body of the research, that is, the practice-based research, I will briefly review the case for artefact as noise within photographic printing, articulate a significant difference between the artefact levels of traditional analogue and Lambda prints, present original dialogical evidence for estrangement in the latter, and identify it via readings of Sigmund Freud's "The Uncanny" and McLuhan's "The Gadget Lover", as a function of the uncanny. I will propose an original rewriting of McLuhan's ideas of "hot" and "cool" media, as well as the cycles of irritation/mediation repression within McLuhan's media theory as a direction for future research, and relate them to a shift from large-scale analogue photographic printing to Lambda printing