Information Analysis for Steganography and Steganalysis in 3D Polygonal Meshes

Information hiding, which embeds a watermark/message over a cover signal, has recently found extensive applications in, for example, copyright protection, content authentication and covert communication. It has been widely considered as an appealing technology to complement conventional cryptographic processes in the field of multimedia security by embedding information into the signal being protected. Generally, information hiding can be classified into two categories: steganography and watermarking. While steganography attempts to embed as much information as possible into a cover signal, watermarking tries to emphasize the robustness of the embedded information at the expense of embedding capacity. In contrast to information hiding, steganalysis aims at detecting whether a given medium has hidden message in it, and, if possible, recover that hidden message. It can be used to measure the security performance of information hiding techniques, meaning a steganalysis resistant steganographic/watermarking method should be imperceptible not only to Human Vision Systems (HVS), but also to intelligent analysis. As yet, 3D information hiding and steganalysis has received relatively less attention compared to image information hiding, despite the proliferation of 3D computer graphics models which are fairly promising information carriers. This thesis focuses on this relatively neglected research area and has the following primary objectives: 1) to investigate the trade-off between embedding capacity and distortion by considering the correlation between spatial and normal/curvature noise in triangle meshes; 2) to design satisfactory 3D steganographic algorithms, taking into account this trade-off; 3) to design robust 3D watermarking algorithms; 4) to propose a steganalysis framework for detecting the existence of the hidden information in 3D models and introduce a universal 3D steganalytic method under this framework. %and demonstrate the performance of the proposed steganalysis by testing it against six well-known 3D steganographic/watermarking methods. The thesis is organized as follows. Chapter 1 describes in detail the background relating to information hiding and steganalysis, as well as the research problems this thesis will be studying. Chapter 2 conducts a survey on the previous information hiding techniques for digital images, 3D models and other medium and also on image steganalysis algorithms. Motivated by the observation that the knowledge of the spatial accuracy of the mesh vertices does not easily translate into information related to the accuracy of other visually important mesh attributes such as normals, Chapters 3 and 4 investigate the impact of modifying vertex coordinates of 3D triangle models on the mesh normals. Chapter 3 presents the results of an empirical investigation, whereas Chapter 4 presents the results of a theoretical study. Based on these results, a high-capacity 3D steganographic algorithm capable of controlling embedding distortion is also presented in Chapter 4. In addition to normal information, several mesh interrogation, processing and rendering algorithms make direct or indirect use of curvature information. Motivated by this, Chapter 5 studies the relation between Discrete Gaussian Curvature (DGC) degradation and vertex coordinate modifications. Chapter 6 proposes a robust watermarking algorithm for 3D polygonal models, based on modifying the histogram of the distances from the model vertices to a point in 3D space. That point is determined by applying Principal Component Analysis (PCA) to the cover model. The use of PCA makes the watermarking method robust against common 3D operations, such as rotation, translation and vertex reordering. In addition, Chapter 6 develops a 3D specific steganalytic algorithm to detect the existence of the hidden messages embedded by one well-known watermarking method. By contrast, the focus of Chapter 7 will be on developing a 3D watermarking algorithm that is resistant to mesh editing or deformation attacks that change the global shape of the mesh. By adopting a framework which has been successfully developed for image steganalysis, Chapter 8 designs a 3D steganalysis method to detect the existence of messages hidden in 3D models with existing steganographic and watermarking algorithms. The efficiency of this steganalytic algorithm has been evaluated on five state-of-the-art 3D watermarking/steganographic methods. Moreover, being a universal steganalytic algorithm can be used as a benchmark for measuring the anti-steganalysis performance of other existing and most importantly future watermarking/steganographic algorithms. Chapter 9 concludes this thesis and also suggests some potential directions for future work

Digital watermarking and novel security devices

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Watermarking security

International audienceThis chapter deals with applications where watermarking is a security primitive included in a larger system protecting the value of multimedia content. In this context, there might exist dishonest users, in the sequel so-called attackers, willing to read/overwrite hidden messages or simply to remove the watermark signal.The goal of this section is to play the role of the attacker. We analyze means to deduce information about the watermarking technique that will later ease the forgery of attacked copies. This chapter first proposes a topology of the threats in Section 6.1, introducing three different concepts: robustness, worst-case attacks, and security. Previous chapter has already discussed watermark robustness. We focus on worst-case attacks in Section 6.2, on the way to measure watermarking security in Section 6.3, and on the classical tools to break a watermarking scheme in Section 6.4. This tour of watermarking security concludes by a summary of what we know and still do not know about it (Section 6.5) and a review of oracle attacks (Section 6.6). Last, Section 6.7 deals with protocol attacks, a notion which underlines the illusion of security that a watermarking primitive might bring when not properly used in some applications

Microwave Dielectrometry Adapted to Environments

Tesis por compendio[ES] La permitividad es una propiedad física de los materiales que describe su comportamiento en presencia de un campo electromagnético. Los sensores de microondas pueden desempeñar un papel esencial en las tareas de detección, supervisión o control de procesos, ya que algunos parámetros fisicoquímicos de los materiales producen cambios medibles en las propiedades dieléctricas. Además, la tecnología de calentamiento por microondas está adquiriendo una relevancia creciente para la transición ecológica y la descarbonización de los procesos industriales, y la permitividad es el parámetro esencial para el desarrollo exitoso de estos nuevos procesos. La permitividad depende de muchos factores, por lo que los métodos de medición de la permitividad deben adaptarse a las necesidades del material y del entorno de medición. El número de aplicaciones que requieren la monitorización o medida de las propiedades dieléctricas, las altas dependencias de esta magnitud bajo diferentes condiciones, y la necesidad de poner esta tecnología al alcance de un usuario más amplio y menos especializado, justifican el desarrollo de este trabajo. Esta tesis pretende desarrollar nuevos dispositivos para la monitorización y caracterización de dieléctricos adaptados a diferentes entornos, cubriendo un amplio rango de formatos, formas y propiedades de los materiales. Las dos primeras publicaciones incluidas en la tesis describen dos enfoques diferentes para abordar las mediciones de permitividad. El primer artículo describe un instrumento versátil, autónomo y fácil de usar para medir la permitividad de materiales dentro de tubos. El diseño de la cavidad logró una excelente sensibilidad, y el estudio de la red de acoplamiento permitió la caracterización de materiales de pérdidas bajas, moderadas y altas con una misma configuración. Este dispositivo incluye un reflectómetro vectorial portátil propio, lo que lo hace portátil y asequible. Las características del instrumento desarrollado permiten un uso sencillo por parte de personal no especializado y proporcionan versatilidad en muchas situaciones. La segunda publicación presenta el diseño específico de una sonda coaxial de extremo abierto con una mayor sensibilidad para determinar la permitividad de productos alimenticios de altas pérdidas en función de la temperatura a frecuencias de RF. Este artículo destaca la importancia de seleccionar la técnica de medición más adecuada, adaptada al entorno y a las particularidades del material, para la determinación apropiada de la permitividad. Los dos artículos siguientes describen el desarrollo y la utilización de un microscopio de microondas de campo cercano con resolución micrométrica para determinar mapas de permitividad de materiales planos heterogéneos a frecuencias de microondas. En ambos trabajos se describen los diferentes elementos que componen el instrumento del microscopio y las técnicas de análisis para determinar los valores de permitividad a partir de las medidas de los parámetros de la resonancia. En el primer trabajo se empleó por primera vez la tecnología de microondas en aplicaciones contra la falsificación, obteniendo la marca dieléctrica de la marca de agua de un billete. Además, este estudio demostró la capacidad de la energía de microondas para detectar marcas ocultas detrás de capas dieléctricas o metálicas, lo que abre nuevas posibilidades para el desarrollo de elementos de seguridad ópticamente opacos e imposibles de rastrear por medios ópticos. El segundo estudio demuestra la versatilidad de este sistema para determinar las propiedades dieléctricas de materiales planos heterogéneos midiendo la respuesta dieléctrica de especímenes de roca. Los métodos desarrollados en esta tesis aumentan la cartera de sistemas de caracterización dieléctrica y pueden ayudar a una amplia gama de sectores científicos e industriales en las tareas de monitorización y caracterización dieléctrica, haciendo estos trabajos más cómodos y accesibles.[CA] La permitivitat és una propietat física dels materials que descriu el seu comportament en presència d'un camp electromagnètic. Els sensors de microones poden exercir un paper essencial en les tasques de detecció, supervisió o control de processos, ja que alguns paràmetres fisicoquímics dels materials produeixen canvis mesurables en les propietats dielèctriques. A més, la tecnologia de calfament per microones està adquirint una rellevància creixent per a la transició ecològica i la descarbonització dels processos industrials, i la permitivitat és el paràmetre essencial per al desenvolupament reeixit d'aquests nous processos. La permitivitat depén de molts factors i, per tant, els mètodes de mesurament de la permitivitat han d'adaptar-se a les necessitats del material i de l'entorn de mesurament. El nombre d'aplicacions que requereixen el monitoratge o mesura de les propietats dielèctriques, les altes dependències d'aquesta magnitud sota diferents condicions, i la necessitat de posar aquesta tecnologia a l'abast d'un usuari més ampli i menys especialitzat, justifiquen el desenvolupament d'aquest treball. Aquesta tesi pretén desenvolupar nous dispositius per al monitoratge i caracterització de dielèctrics adaptats a diferents entorns, cobrint un ampli rang de formats, formes i propietats dels materials. Les dues primeres publicacions incloses en la tesi descriuen dos enfocaments diferents per a abordar els mesuraments de permitivitat. El primer article descriu un instrument versàtil, autònom i fàcil d'usar per a mesurar la permitivitat de materials dins de tubs. El disseny de la cavitat va aconseguir una excel·lent sensibilitat, i l'estudi de la xarxa d'acoblament va permetre la caracterització de materials de pèrdues baixes, moderades i altes amb una mateixa configuració. Aquest dispositiu inclou un reflectòmetre vectorial portàtil propi, la qual cosa el fa portàtil i assequible. Les característiques de l'instrument desenvolupat permeten un ús senzill per part de personal no especialitzat i proporcionen versatilitat en moltes situacions. La segona publicació presenta el disseny específic de una sonda coaxial d'extrem obert amb una major sensibilitat per a determinar la permitivitat de productes alimentaris d'altes pèrdues en funció de la temperatura a freqüències de RF. Aquest article destaca la importància de seleccionar la tècnica de mesurament més adequat, adaptada a l'entorn i a les particularitats del material, per a la determinació apropiada de la permitivitat. Els dos articles següents descriuen el desenvolupament i la utilització d'un microscopi de microones de camp pròxim amb resolució micromètrica per a determinar mapes de permitivitat de materials plans heterogenis a freqüències de microones. En tots dos treballs es descriuen els diferents elements que componen l'instrument del microscopi i les tècniques d'anàlisis per a determinar els valors de permitivitat a partir de les mesures dels paràmetres de la ressonància. En el primer treball es va emprar per primera vegada la tecnologia de microones en aplicacions contra la falsificació, obtenint la marca dielèctrica de la marca d'aigua d'un bitllet. A més, aquest estudi va demostrar la capacitat de l'energia de microones per a detectar marques ocultes darrere de capes dielèctriques o metàl·liques, la qual cosa obri noves possibilitats per al desenvolupament d'elements de seguretat òpticament opacs i impossibles de rastrejar per mitjans òptics. El segon estudi demostra la versatilitat d'aquest sistema per a determinar les propietats dielèctriques de materials plans heterogenis mesurant la resposta dielèctrica d'espècimens de roca. Els mètodes desenvolupats en aquesta tesi augmenten la cartera de sistemes de caracterització dielèctrica i poden ajudar a una àmplia gamma de sectors científics i industrials en les tasques de monitoratge i caracterització dielèctrica, fent aquests treballs més còmodes i accessibles.[EN] Permittivity is a physical property of materials describing their behavior in the presence of an electromagnetic field. Microwave sensors can play an essential role in detecting, monitoring, or process control tasks as some physicochemical parameters of materials produce measurable changes in dielectric properties. Besides, microwave heating technology is gaining increasing relevance for the ecological transition and decarbonization of industrial processes, and permittivity is the essential parameter for the successful development of these new processes. Permittivity depends on many factors and thus, permittivity measurement methods must be adapted to the needs of the material and the measurement environment. The number of applications that require the monitoring or measurement of dielectric properties, the high dependencies of this magnitude under different conditions, and the need to make this technology available to a broader and less specialized user justify the development of this work. This thesis aims to develop new devices for the monitoring and characterization of dielectrics adapted to different environments, covering a wide range of materials' formats, shapes, and properties. The first two publications included in the thesis describe two different approaches to address permittivity measurements. The first paper describes a versatile, stand-alone, and easy-to-use instrument for measuring the permittivity materials inside tubes. The design of the cavity achieved an excellent sensitivity, and the study of the coupling network allowed the characterization of low, moderate, and high-loss materials with the same setup. This device included an in-house portable vector reflectometer, making it portable and cost-affordable. The features of the developed instrument allow straightforward use by non-specialized personnel and provide versatility in many situations. The second publication presents a specific open-ended coaxial design with increased sensitivity to determine the permittivity of lossy food products as a function of temperature at RF frequencies. This paper highlight the relevance of selecting the most suitable measurement technique, adapted to the environment and particularities of the material, for the appropriate determination of permittivity. The following two papers describe the development and use of a near-field scanning microwave microscope with micrometric resolution to determine permittivity maps of heterogeneous planar materials at microwave frequencies. The different elements comprising the microscope instrument and the analysis techniques to determine permittivity values from the resonance measurements were described throughout both works. In the first paper, microwave technology was employed for the first time in anti-counterfeiting applications by obtaining the dielectric mark of a banknote watermark. Besides, this study showed the ability of microwave energy to detect hidden marks behind dielectric or metallic layers, opening new possibilities for developing optically opaque security features untraceable by optical means. The second study demonstrates the versatility of this system in determining the dielectric properties of heterogeneous planar materials by measuring the dielectric response of rock specimens. The methods developed in this thesis dissertation increase the portfolio of dielectric characterization systems and can help a wide range of scientific and industrial sectors in dielectric monitoring and characterization tasks, making these works more convenient and accessible.Financial support through the grant reference BES-2016-077296 of the call Convocatoria de las ayudas para contratos predoctorales para la formación de doctores de 2016 by Ministerio de Economía y Competitividad (MINECO) and by European Social Funds (ESF) of European Union is also gratefully acknowledgedGutiérrez Cano, JD. (2022). Microwave Dielectrometry Adapted to Environments [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/186351TESISCompendi

Segmentation, registration,and selective watermarking of retinal images

In this dissertation, I investigated some fundamental issues related to medical image segmentation, registration, and watermarking. I used color retinal fundus images to perform my study because of the rich representation of different objects (blood vessels, microaneurysms, hemorrhages, exudates, etc.) that are pathologically important and have close resemblance in shapes and colors. To attack this complex subject, I developed a divide-and-conquer strategy to address related issues step-by-step and to optimize the parameters of different algorithm steps. Most, if not all, objects in our discussion are related. The algorithms for detection, registration, and protection of different objects need to consider how to differentiate the foreground from the background and be able to correctly characterize the features of the image objects and their geometric properties. To address these problems, I characterized the shapes of blood vessels in retinal images and proposed the algorithms to extract the features of blood vessels. A tracing algorithm was developed for the detection of blood vessels along the vascular network. Due to the noise interference and various image qualities, the robust segmentation techniques were used for the accurate characterization of the objects shapes and verification. Based on the segmentation results, a registration algorithm was developed, which uses the bifurcation and cross-over points of blood vessels to establish the correspondence between the images and derive the transformation that aligns the images. A Region-of-Interest (ROI) based watermarking scheme was proposed for image authenticity. It uses linear segments extracted from the image as reference locations for embedding and detecting watermark. Global and locally-randomized synchronization schemes were proposed for bit-sequence synchronization of a watermark. The scheme is robust against common image processing and geometric distortions (rotation and scaling), and it can detect alternations such as moving or removing of the image content

DIGITAL WATERMARKING FOR COMPACT DISCS AND THEIR EFFECT ON THE ERROR CORRECTION SYSTEM

A new technique, based on current compact disc technology, to image the transparent surface of a compact disc, or additionally the reflective information layer, has been designed, implemented and evaluated. This technique (image capture technique) has been tested and successfully applied to the detection of mechanically introduced compact disc watermarks and biometrical information with a resolution of 1.6um x l4um. Software has been written which, when used with the image capture technique, recognises a compact disc based on its error distribution. The software detects digital watermarks which cause either laser signal distortions or decoding error events. Watermarks serve as secure media identifiers. The complete channel coding of a Compact Disc Audio system including EFM modulation, error-correction and interleaving have been implemented in software. The performance of the error correction system of the compact disc has been assessed using this simulation model. An embedded data channel holding watermark data has been investigated. The covert channel is implemented by means of the error-correction ability of the Compact Disc system and was realised by aforementioned techniques like engraving the reflective layer or the polysubstrate layer. Computer simulations show that watermarking schemes, composed of regularly distributed single errors, impose a minimum effect on the error correction system. Error rates increase by a factor of ten if regular single-symbol errors per frame are introduced - all other patterns further increase the overall error rates. Results show that background signal noise has to be reduced by a factor of 60% to account for the additional burden of this optimal watermark pattern. Two decoding strategies, usually employed in modern CD decoders, have been examined. Simulations take emulated bursty background noise as it appears in user-handled discs into account. Variations in output error rates, depending on the decoder and the type of background noise became apparant. At low error rates {r < 0.003) the output symbol error rate for a bursty background differs by 20% depending on the decoder. Differences between a typical burst error distribution caused by user-handling and a non-burst error distribution has been found to be approximately 1% with the higher performing decoder. Simulation results show that the drop of the error-correction rates due to the presence of a watermark pattern quantitatively depends on the characteristic type of the background noise. A four times smaller change to the overall error rate was observed when adding a regular watermark pattern to a characteristic background noise, as caused by user-handling, compared to a non-bursty background

Validating Geoclaw for Simulating Teton Dam Failure by Comparison with HEC-RAS Results and Historical Observations

The combination of dams degrading with age and other factors like climate change, technical errors, and human errors lead to dams breaching and failing worldwide. In the United States, over 40,000 dams pose a threat to downstream inhabited areas and constitute a widespread hazard if they were to breach. Therefore, it is critical to accurately predict the resultant floods’ downstream flow behavior to create a more resilient community. By improving research, we can concurrently develop and improve mitigation strategies for downstream communities. This study benchmarks the GeoClaw numerical modeling software with the well-documented 1976 Teton Dam failure. A vital tool in dam failure research is two-dimensional (2D) coupled numerical hydrodynamic modeling for dam-breaks. This study aims to benchmark the GeoClaw software, a 2D hydraulic model with novel adaptive mesh refinement (AMR) capabilities (http://www.clawpack.org/) for dam failure analysis by a systematic comparison of dam breach inundation response to both historical data and the industry-standard software HEC-RAS (Hydraulic Engineering Center - River Analysis System). The objectives of this study are to: Determine the suitability of the GeoClaw software based on its capability to resolve inundation extent and flood front arrival times Compare an instantaneous dam breach with a time-dependent breach formation Quantify the uncertainty of the HEC-RAS model through a sensitivity analysis This study concludes the 2D GeoClaw dam break model verified by its stability and accuracy, conservation properties, and calibration with the historical hydrological data and HEC-RAS results at a low computational cost. The overall performance of GeoClaw indicates that it is a validated tool for the simulation of dam-break waves in real-cases with future work. The outcomes of this study will assist dam owners, floodplain managers, and emergency managers alike by providing an additional tool for estimating the impacts of dam failures

Assessing the Effectiveness of Louisiana\u27s Freshwater Diversion Projects Using Remote Sensing

Southern Louisiana is experiencing a dramatic loss of freshwater wetlands as a result of natural and man-made changes in the landscape. Multitempral remotely sensed data were used to examine the impact of the Caernarvon Freshwater Diversion Structure, built in 1991 to divert water to Breton Sound. Satellite imagery data covering the period from 1974 to 2006 were analyzed by computing several spectral indices including NDVI, VI, IR/R, Sqrt IR/R, T-NDVI, and NDWI, as well as principle component analysis. The resulting enhanced images were classified into two classes, vegetation or open water. The ratios of vegetation to open water were then calculated and the changes graphed over the 1974-2006 timeframe. The results indicated that despite the infusion of freshwater, the open water portion of the Breton Sound area continued to expand, indeed the expansion rate increased from approximately 0.25% per year before construction of Caernarvon to 0.45% per year after construction