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Zakaria, Ahmad. "Batch steganography and pooled steganalysis in JPEG images." Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTS079.
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RÉSUMÉ :La stéganographie par lot consiste à dissimuler un message en le répartissant dans un ensemble d’images, tandis que la stéganalyse groupée consiste à analyser un ensemble d’images pour conclure à la présence ou non d’un message caché. Il existe de nombreuses stratégies d’étalement d’un message et on peut raisonnablement penser que le stéganalyste ne connaît pas celle qui est utilisée, mais il peut supposer que le stéganographe utilise le même algorithme d’insertion pour toutes les images. Dans ce cas, on peut montrer que la solution la plus appropriée pour la stéganalyse groupée est d’utiliser un unique détecteur quantitatif (c'est-à-dire qui prédit la taille du message caché), d’évaluer pour chaque image la taille du message caché (qui peut être nulle s'il n'y en a pas) et de faire la moyenne des tailles (qui sont finalement considérées comme des scores) obtenues sur l'ensemble des images.Quelle serait la solution optimale si maintenant, le stéganalyste pouvait discriminer la stratégie d’étalement parmi un ensemble de stratégies connues. Le stéganalyste pourrait-il utiliser un algorithme de stéganalyse groupé meilleur que la moyenne des scores ? Le stéganalyste pourrait-il obtenir des résultats proches du scénario dit "clairvoyant" où l’on suppose qu’il connaît exactement la stratégie d’étalement ?Dans cette thèse, nous essayons de répondre à ces questions en proposant une architecture de stéganalyse groupée fondé sur un détecteur quantitatif d’images et une fonction de groupement optimisée des scores. La première contribution est une étude des algorithmes de stéganalyse quantitatifs afin de décider lequel est le mieux adapté à la stéganalyse groupée. Pour cela, nous proposons d’étendre cette comparaison aux algorithmes de stéganalyse binaires et nous proposons une méthodologie pour passer des résultats de la stéganalyse binaire en stéganalyse quantitative et réciproquement.Le cœur de la thèse se situe dans la deuxième contribution. Nous étudions le scénario où le stéganalyste ne connaît pas la stratégie d’étalement. Nous proposons alors une fonction de groupement optimisée des résultats fondés sur un ensemble de stratégies d’étalement ce qui permet d’améliorer la précision de la stéganalyse groupée par rapport à une simple moyenne. Cette fonction de groupement est calculée en utilisant des techniques d’apprentissage supervisé. Les résultats expérimentaux obtenus avec six stratégies d’étalement différentes et un détecteur quantitatif de l’état de l’art confirment notre hypothèse. Notre fonction de groupement obtient des résultats proches d’un stéganalyste clairvoyant qui est censé connaître la stratégie d’étalement.Mots clés : Sécurité multimédia, Stéganographie par lot, Stéganalyse groupée, Apprentissage machineABSTRACT:Batch steganography consists of hiding a message by spreading it out in a set of images, while pooled steganalysis consists of analyzing a set of images to conclude whether or not a hidden message is present. There are many strategies for spreading a message and it is reasonable to assume that the steganalyst does not know which one is being used, but it can be assumed that the steganographer uses the same embedding algorithm for all images. In this case, it can be shown that the most appropriate solution for pooled steganalysis is to use a single quantitative detector (i.e. one that predicts the size of the hidden message), to evaluate for each image the size, the hidden message (which can be zero if there is none), and to average the sizes (which are finally considered as scores) obtained over all the images.What would be the optimal solution if now the steganalyst could discriminate the spreading strategy among a set of known strategies. Could the steganalyst use a pooled steganalysis algorithm that is better than averaging the scores? Could the steganalyst obtain results close to the so-called "clairvoyant" scenario where it is assumed that the steganalyst knows exactly the spreading strategy?In this thesis, we try to answer these questions by proposing a pooled steganalysis architecture based on a quantitative image detector and an optimized score pooling function. The first contribution is a study of quantitative steganalysis algorithms in order to decide which one is best suited for pooled steganalysis. For this purpose, we propose to extend this comparison to binary steganalysis algorithms and we propose a methodology to switch from binary steganalysis results to quantitative steganalysis and vice versa.The core of the thesis lies in the second contribution. We study the scenario where the steganalyst does not know the spreading strategy. We then propose an optimized pooling function of the results based on a set of spreading strategies which improves the accuracy of the pooled steganalysis compared to a simple average. This pooling function is computed using supervised learning techniques. Experimental results obtained with six different spreading strategies and a state-of-the-art quantitative detector confirm our hypothesis. Our pooling function gives results close to a clairvoyant steganalyst who is supposed to know the spreading strategy.Keywords: Multimedia Security, Batch Steganography, Pooled Steganalysis, Machine Learning
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Le, Pham [Verfasser]. "Detection of Steganography in Images with Statistical Models / Pham Le." München : Verlag Dr. Hut, 2014. http://d-nb.info/1052375162/34.
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Oliveira, Fábio Borges de. "Analysis of the cryptography security and steganography in images sequences." Laboratório Nacional de Computação Científica, 2007. http://www.lncc.br/tdmc/tde_busca/arquivo.php?codArquivo=134.
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Information security is being considered of great importance to the private and governamental institutions. For this reason, we opted to conduct a study of security in this dissertation. We started with an introduction to the information theory, and then we proposed a new kind of Perfect Secrecy cryptographic and finally made a study of steganography in an image sequence, in which we suggest a more aggressive steganography in coefficients of the discrete cosine transform.A segurança da informação vem sendo considerada de grande importância para as instituições privadas e governamentais. Por este motivo, optamos em realizar um estudo sobre segurança nesta dissertação. Iniciamos com uma introdução à teoria da informação, partimos para métodos de criptografia onde propomos um novo tipo de Segredo Perfeito e finalmente fazemos um estudo de esteganografia em uma sequência de imagens, onde propomos uma esteganografia mais agressiva nos coeficientes da transformada discreta de cosseno.
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ESCOBAR, JAISSE GRELA. "A TOOL FOR TRACKING VIDEOS AND IMAGES USING STEGANOGRAPHY TECHNIQUES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=25814@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Na indústria de TV frequentemente ocorrem vazamentos de materiais de filmagem quando estes se distribuem entre os colaboradores de produção, prejudicando grandemente as empresas. Neste trabalho propomos uma ferramenta que, utilizando técnicas de esteganografia adaptativa, permite detectar a fonte do vazamento com um elevado grau de confiança. Um requisito importante é que a informação mascarada no vídeo (ou na imagem) resista a operações de processamento tais como redimensionamento e mudança de resolução. A ideia é usar o algoritmo Speeded Up Robust Features (SURF), estratégia consagrada, na detecção e descrição de características em imagens para detectar regiões robustas da imagem e inserir nelas uma pequena identificação mascarada. A ferramenta utiliza a transformada Haar – Discrete Wavelet Transform em duas dimensões, para depois fazer modificações na imagem. Esta dissertação propõe direções iniciais promissoras para a identificação segura de certificados de origem de imagens e vídeos.
In the TV industry, leaks of film materials occur frequently when they are distributed among the members of the production team, causing great harm to the companies. In this paper, we propose a tool that allows detecting the source of the leak with a high degree of confidence, using techniques of adaptive steganography. An important requirement is that the information embedded in the video (or image) should resist to processing operations such as resizing and resolution changes. The idea is to use the Speeded Up Robust Features (SURF) algorithm, a well-known strategy for detection and description of images features, to detect the robust regions of the image and insert a small masked identification in them. The tool uses the Haar - Discrete Wavelet Transform in two dimensions and then modifies the image. This dissertation proposes promising initial directions for secure identification of the certificate of origin of digital images and videos.
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Grajeda, Marín Ismael Rufino. "Increase in the information payload for steganography in digital images." Tesis de Licenciatura, Universidad Autónoma del Estado de México, 2019. http://hdl.handle.net/20.500.11799/105009.
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El presente artículo se deriva de una investigación previa realizada en la facultad de ingeniería [8], en la cual se propuso y desarrolló un algoritmo de esteganografía en imágenes digitales que permitiera mejorar en
varios aspectos los métodos previamente existentes. Se desarrolló una adaptación al método denominado "diferencia de píxeles por tres vías". Con el objetivo de apoyar en la experimentación se realizó un estudio implementación del mismo, derivado de los resultados experimentales se desprendieron 3 nuevos algoritmos.
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Cerkez, Paul. "Automated Detection of Semagram-Laden Images." NSUWorks, 2012. http://nsuworks.nova.edu/gscis_etd/115.
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Digital steganography is gaining wide acceptance in the world of electronic copyright stamping. Digital media that are easy to steal, such as graphics, photos and audio files, are being tagged with both visible and invisible copyright stamp known as a digital watermark. However, these same methodologies are also used to hide communications between actors in criminal or covert activities. An inherent difficulty in developing steganography attacks is overcoming the variety of methods for hiding a message and the multitude of choices of available media. The steganalyst cannot create an attack until the hidden content method appears. When a message is visually transmitted in a non-textual format (i.e., in an image) it is referred to as a semagram.
Semagrams are a subset of steganography and are relatively easy to create. However, detecting a hidden message in an image-based semagram is more difficult than detecting digital modifications to an image's structure. The trend in steganography is a decrease in detectable digital traces, and a move toward semagrams. This research outlines the creation of a novel, computer-based application, designed to detect the likely presence of a Morse Code based semagram message in an image. This application capitalizes on the adaptability and learning capabilities of various artificial neural network (NN) architectures, most notably hierarchical architectures.
Four NN architectures [feed-forward Back-Propagation NN (BPNN), Self organizing Map (SOM), Neural Abstraction Pyramid (NAP), and a Hybrid Custom Network (HCN)] were tested for applicability to this domain with the best performing one being the HCN. Each NN was given a baseline set of training images (quantity based on NN architecture) then test images were presented, (each test set having 3,337 images). There were 36 levels of testing. Each subsequent test set representing an increase in complexity over the previous one. In the end, the HCN proved to be the NN of choice from among the four tested. The final HCN implementation was the only network able to successfully perform against all 36 levels. Additionally, the HCN, while only being trained on the base Morse Code images, successfully detected images in the 9 test sets of Morse Code isomorphs.
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Chandrababu, Aron. "Using an artificial neural network to detect the presence of image steganography." Akron, OH : University of Akron, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1237343521.
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Thesis (M.S.)--University of Akron, Dept. of Computer Science, 2009."May, 2009." Title from electronic thesis title page (viewed 11/18/2009) Advisor, Kathy J. Liszka; Faculty Readers, Timothy W. O'Neil, Tim Margush; Department Chair, Wolfgang Pelz; Dean of the College, Chand Midha; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Thorpe, Christopher. "Compression aided feature based steganalysis of perturbed quantization steganography in JPEG images." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 114 p, 2008. http://proquest.umi.com/pqdweb?did=1459914021&sid=6&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Rwabutaza, Allan Anthony. "A Cryptanalysis Methodology for the Reverse Engineering of Encrypted Information in Images." Wright State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=wright1261417786.
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Abdulla, Alan Anwer. "Exploiting similarities between secret and cover images for improved embedding efficiency and security in digital steganography." Thesis, University of Buckingham, 2015. http://bear.buckingham.ac.uk/149/.
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The rapid advancements in digital communication technology and huge increase in computer power have generated an exponential growth in the use of the Internet for various commercial, governmental and social interactions that involve transmission of a variety of complex data and multimedia objects. Securing the content of sensitive as well as personal transactions over open networks while ensuring the privacy of information has become essential but increasingly challenging. Therefore, information and multimedia security research area attracts more and more interest, and its scope of applications expands significantly. Communication security mechanisms have been investigated and developed to protect information privacy with Encryption and Steganography providing the two most obvious solutions. Encrypting a secret message transforms it to a noise-like data which is observable but meaningless, while Steganography conceals the very existence of secret information by hiding in mundane communication that does not attract unwelcome snooping. Digital steganography is concerned with using images, videos and audio signals as cover objects for hiding secret bit-streams. Suitability of media files for such purposes is due to the high degree of redundancy as well as being the most widely exchanged digital data. Over the last two decades, there has been a plethora of research that aim to develop new hiding schemes to overcome the variety of challenges relating to imperceptibility of the hidden secrets, payload capacity, efficiency of embedding and robustness against steganalysis attacks. Most existing techniques treat secrets as random bit-streams even when dealing with non-random signals such as images that may add to the toughness of the challenges. This thesis is devoted to investigate and develop steganography schemes for embedding secret images in image files. While many existing schemes have been developed to perform well with respect to one or more of the above objectives, we aim to achieve optimal performance in terms of all these objectives. We shall only be concerned with embedding secret images in the spatial domain of cover images. The main difficulty in addressing the different challenges stems from the fact that the act of embedding results in changing cover image pixel values that cannot be avoided, although these changes may not be easy to detect by the human eye. These pixel changes is a consequence of dissimilarity between the cover LSB plane and the secretimage bit-stream, and result in changes to the statistical parameters of stego-image bit-planes as well as to local image features. Steganalysis tools exploit these effects to model targeted as well as blind attacks. These challenges are usually dealt with by randomising the changes to the LSB, using different/multiple bit-planes to embed one or more secret bits using elaborate schemes, or embedding in certain regions that are noise-tolerant. Our innovative approach to deal with these challenges is first to develop some image procedures and models that result in increasing similarity between the cover image LSB plane and the secret image bit-stream. This will be achieved in two novel steps involving manipulation of both the secret image and the cover image, prior to embedding, that result a higher 0:1 ratio in both the secret bit-stream and the cover pixels‘ LSB plane. For the secret images, we exploit the fact that image pixel values are in general neither uniformly distributed, as is the case of random secrets, nor spatially stationary. We shall develop three secret image pre-processing algorithms to transform the secret image bit-stream for increased 0:1 ratio. Two of these are similar, but one in the spatial domain and the other in the Wavelet domain. In both cases, the most frequent pixels are mapped onto bytes with more 0s. The third method, process blocks by subtracting their means from their pixel values and hence reducing the require number of bits to represent these blocks. In other words, this third algorithm also reduces the length of the secret image bit-stream without loss of information. We shall demonstrate that these algorithms yield a significant increase in the secret image bit-stream 0:1 ratio, the one that based on the Wavelet domain is the best-performing with 80% ratio. For the cover images, we exploit the fact that pixel value decomposition schemes, based on Fibonacci or other defining sequences that differ from the usual binary scheme, expand the number of bit-planes and thereby may help increase the 0:1 ratio in cover image LSB plane. We investigate some such existing techniques and demonstrate that these schemes indeed lead to increased 0:1 ratio in the corresponding cover image LSB plane. We also develop a new extension of the binary decomposition scheme that is the best-performing one with 77% ratio. We exploit the above two steps strategy to propose a bit-plane(s) mapping embedding technique, instead of bit-plane(s) replacement to make each cover pixel usable for secret embedding. This is motivated by the observation that non-binary pixel decomposition schemes also result in decreasing the number of possible patterns for the three first bit-planes to 4 or 5 instead of 8. We shall demonstrate that the combination of the mapping-based embedding scheme and the two steps strategy produces stego-images that have minimal distortion, i.e. reducing the number of the cover pixels changes after message embedding and increasing embedding efficiency. We shall also demonstrate that these schemes result in reasonable stego-image quality and are robust against all the targeted steganalysis tools but not against the blind SRM tool. We shall finally identify possible future work to achieve robustness against SRM at some payload rates and further improve stego-image quality.
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Abdulrahman, Hasan. "Oriented filters for feature extraction in digital Images : Application to corners detection, Contours evaluation and color Steganalysis." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTS077/document.
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L’interprétation du contenu de l’image est un objectif très important dans le traitement de l’image et la vision par ordinateur. Par conséquent, plusieurs chercheurs y sont intéressés. Une image contient des informations multiples qui peuvent être étudiés, telles que la couleur, les formes, les arêtes, les angles, la taille et l’orientation. En outre, les contours contiennent les structures les plus importantes de l’image. Afin d’extraire les caractéristiques du contour d’un objet, nous devons détecter les bords de cet objet. La détection de bords est un point clé dans plusieurs applications, telles que :la restauration, l’amélioration de l’image, la stéganographie, le filigrane, la récupération, la reconnaissance et la compression de l’image, etc. Toutefois, l’évaluation de la performance de la méthode de détection de bords reste un grand défi. Les images numériques sont parfois modifiées par une procédure légale ou illégale afin d’envoyer des données secrètes ou spéciales. Afin d’être moins visibles, la plupart des méthodes stéganographiques modifient les valeurs de pixels dans les bords/textures de parties de l’image. Par conséquent, il est important de détecter la présence de données cachées dans les images numériques. Cette thèse est divisée principalement en deux parties.La première partie discute l’évaluation des méthodes de détection des bords du filtrage, des contours et des angles. En effet, cinq contributions sont présentées dans cette partie : d’abord, nous avons proposé un nouveau plan de surveillance normalisée de mesure de la qualité. En second lieu, nous avons proposé une nouvelle technique pour évaluer les méthodes de détection des bords de filtrage impliquant le score minimal des mesures considérées. En plus, nous avons construit une nouvelle vérité terrain de la carte de bords étiquetée d’une manière semi-automatique pour des images réelles.En troisième lieu, nous avons proposé une nouvelle mesure prenant en compte les distances de faux points positifs pour évaluer un détecteur de bords d’une manière objective. Enfin, nous avons proposé une nouvelle approche de détection de bords qui combine la dérivée directionnelle et l’homogénéité des grains. Notre approche proposée est plus stable et robuste au bruit que dix autres méthodes célèbres de détection. La seconde partie discute la stéganalyse de l’image en couleurs, basée sur l’apprentissage automatique (machine learning). En effet, trois contributions sont présentées dans cette partie : d’abord, nous avons proposé une nouvelle méthode de stéganalyse de l’image en couleurs, basée sur l’extraction de caractéristiques de couleurs à partir de corrélations entre les gradients de canaux rouge, vert et bleu. En fait, ces caractéristiques donnent le cosinus des angles entre les gradients. En second lieu, nous avons proposé une nouvelle méthode de stéganalyse de l’image en couleurs, basée sur des mesures géométriques obtenues par le sinus et le cosinus des angles de gradients entre tous les canaux de couleurs. Enfin, nous avons proposé une nouvelle méthode de stéganalyse de l’image en couleurs, basée sur une banque de filtres gaussiens orientables. Toutes les trois méthodes proposées présentent des résultats intéressants et prometteur en devançant l’état de l’art de la stéganalyse en couleursInterpretation of image contents is very important objective in image processing and computer vision. Wherefore, it has received much attention of researchers. An image contains a lot of information which can be studied such as color, shapes, edges, corners, size, and orientation. Moreover, contours include the most important structures in the image. In order to extract features contour of an object, we must detect the edges of that object. Edge detection results, remains a key point and very important step in wide range of applications such as: image restoration, enhancement, steganography, watermarking, image retrieval, recognition, compression, and etc. An efficient boundary detection method should create a contour image containing edges at their correct locations with a minimum of misclassified pixels. However, the performance evaluationof the edge detection results is still a challenging problem. The digital images are sometimes modify by a legal or illegal data in order to send special or secret data. These changes modify slight coefficient values of the image. In order to be less visible, most of the steganography methods modify the pixel values in the edge/texture image areas. Therefore, it is important to detect the presence of hidden data in digital images. This thesis is divided mainly into two main parts. The first part, deals with filtering edge detection, contours evaluation and corners detection methods. More deeply, there are five contributions are presented in this part: first, proposed a new normalized supervised edge map quality measure. The strategy to normalize the evaluation enables to consider a score close to 0 as a good edge map, whereas a score 1 translates a poor segmentation. Second, proposed a new technique to evaluate filtering edge detection methods involving the minimum score of the considerate measures. Moreover, build a new ground truth edge map labelled in semi-automatic way in real images. Third, proposed a new measure takes into account the distances of false positive points to evaluate an edge detector in an objective way. Finally, proposed a new approach for corner detection based on the combination of directional derivative and homogeneity kernels. The proposed approach remains more stable and robust to noise than ten famous corner detection methods. The second part, deals with color image steganalysis, based on a machine learning classification. More deeply, there are three contributionsare presented in this part: first, proposed a new color image steganalysis method based on extract color features from correlations between the gradients of red, green and blue channels. Since these features give the cosine of angles between gradients. Second, proposed a new color steganalysis method based on geometric measures obtained by the sine and cosine of gradient angles between all the color channels. Finally, proposed a new approach for color image steganalysisbased on steerable Gaussian filters Bank.All the three proposed methods in this part, provide interesting and promising results by outperforming the state-of-art color image steganalysis
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Kouider, Sarra. "Insertion adaptative en stéganographie : application aux images numériques dans le domaine spatial." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2013. http://tel.archives-ouvertes.fr/tel-01020745.
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La stéganographie est l'art de la communication secrète. L'objectif est de dissimuler un message secret dans un médium anodin de sorte qu'il soit indétectable. De nos jours, avec la généralisation d'Internet et l'apparition des supports numériques (fichiers audio, vidéos ou images), plusieurs philosophies de conception de schéma stéganographique ont été proposées. Parmi les méthodes actuelles appliquées aux images numériques naturelles, nous trouvons les méthodes d'insertion adaptative, dont le principe repose sur la modification du médium de couverture avec une garantie d'avoir un certain niveau de sécurité. Ces méthodes représentent une véritable avancée en stéganographie.Dans ce manuscrit, après avoir rappelé les concepts récents de stéganographie adaptative, nous présentons une procédure automatique et complète pour l'insertion adaptative de données secrètes dans des images numériques naturelles. L'approche proposée est une " méta-méthode " basée " oracle ", appelée ASO (Adaptive Steganography by Oracle), qui permet de préserver à la fois la distribution de l'image de couverture et la distribution de la base d'images utilisée par l'émetteur. Notre approche permet d'obtenir des résultats nettement supérieurs aux méthodes actuelles de l'état de l'art, et est donc l'une, si ce n'est la meilleure approche du moment. Par ailleurs, nous définissons également un nouveau paradigme en stéganographie qui est la stéganographie par base, ainsi qu'une nouvelle mesure de sélection pour les images stéganographiées, permettant d'améliorer encore plus les performances de notre schéma d'insertion. Les différentes expérimentations, que nous avons effectuées sur des images réelles, ont confirmé la pertinence de cette nouvelle approche.
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Guettari, Nadjib. "Évaluation du contenu d'une image couleur par mesure basée pixel et classification par la théorie des fonctions de croyance." Thesis, Poitiers, 2017. http://www.theses.fr/2017POIT2275/document.
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De nos jours, il est devenu de plus en plus simple pour qui que ce soit de prendre des photos avec des appareils photo numériques, de télécharger ces images sur l'ordinateur et d'utiliser différents logiciels de traitement d'image pour appliquer des modification sur ces images (compression, débruitage, transmission, etc.). Cependant, ces traitements entraînent des dégradations qui influent sur la qualité visuelle de l'image. De plus, avec la généralisation de l'internet et la croissance de la messagerie électronique, des logiciels sophistiqués de retouche d'images se sont démocratisés permettant de falsifier des images à des fins légitimes ou malveillantes pour des communications confidentielles ou secrètes. Dans ce contexte, la stéganographie constitue une méthode de choix pour dissimuler et transmettre de l'information.Dans ce manuscrit, nous avons abordé deux problèmes : l'évaluation de la qualité d'image et la détection d'une modification ou la présence d'informations cachées dans une image. L'objectif dans un premier temps est de développer une mesure sans référence permettant d'évaluer de manière automatique la qualité d'une image en corrélation avec l'appréciation visuelle humaine. Ensuite proposer un outil de stéganalyse permettant de détecter, avec la meilleure fiabilité possible, la présence d'informations cachées dans des images naturelles. Dans le cadre de cette thèse, l'enjeu est de prendre en compte l'imperfection des données manipulées provenant de différentes sources d'information avec différents degrés de précision. Dans ce contexte, afin de profiter entièrement de l'ensemble de ces informations, nous proposons d'utiliser la théorie des fonctions de croyance. Cette théorie permet de représenter les connaissances d'une manière relativement naturelle sous la forme d'une structure de croyances. Nous avons proposé une nouvelle mesure sans référence d'évaluation de la qualité d'image capable d'estimer la qualité des images dégradées avec de multiple types de distorsion. Cette approche appelée wms-EVreg2 est basée sur la fusion de différentes caractéristiques statistiques, extraites de l'image, en fonction de la fiabilité de chaque ensemble de caractéristiques estimée à travers la matrice de confusion. À partir des différentes expérimentations, nous avons constaté que wms-EVreg2 présente une bonne corrélation avec les scores de qualité subjectifs et fournit des performances de prédiction de qualité compétitives par rapport aux mesures avec référence.Pour le deuxième problème abordé, nous avons proposé un schéma de stéganalyse basé sur la théorie des fonctions de croyance construit sur des sous-espaces aléatoires des caractéristiques. La performance de la méthode proposée a été évaluée sur différents algorithmes de dissimulation dans le domaine de transformé JPEG ainsi que dans le domaine spatial. Ces tests expérimentaux ont montré l'efficacité de la méthode proposée dans certains cadres d'applications. Cependant, il reste de nombreuses configurations qui résident indétectablesNowadays it has become increasingly simpler for anyone to take pictures with digital cameras, to download these images to the computer and to use different image processing software to apply modifications on these images (Compression, denoising, transmission, etc.). However, these treatments lead to degradations which affect the visual quality of the image. In addition, with the widespread use of the Internet and the growth of electronic mail, sophisticated image-editing software has been democratised allowing to falsify images for legitimate or malicious purposes for confidential or secret communications. In this context, steganography is a method of choice for embedding and transmitting information.In this manuscript we discussed two issues : the image quality assessment and the detection of modification or the presence of hidden information in an image. The first objective is to develop a No-Reference measure allowing to automatically evaluate the quality of an image in correlation with the human visual appreciation. Then we propose a steganalysis scheme to detect, with the best possible reliability, the presence of information embedded in natural images. In this thesis, the challenge is to take into account the imperfection of the manipulated data coming from different sources of information with different degrees of precision. In this context, in order to take full advantage of all this information, we propose to use the theory of belief functions. This theory makes it possible to represent knowledge in a relatively natural way in the form of a belief structure.We proposed a No-reference image quality assessment measure, which is able to estimate the quality of the degraded images with multiple types of distortion. This approach, called wms-EVreg2, is based on the fusion of different statistical features, extracted from the image, depending on the reliability of each set of features estimated through the confusion matrix. From the various experiments, we found that wms-EVreg2 has a good correlation with subjective quality scores and provides competitive quality prediction performance compared to Full-reference image quality measures.For the second problem addressed, we proposed a steganalysis scheme based on the theory of belief functions constructed on random subspaces of the features. The performance of the proposed method was evaluated on different steganography algorithms in the JPEG transform domain as well as in the spatial domain. These experimental tests have shown the performance of the proposed method in some application frameworks. However, there are many configurations that reside undetectable
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Cheddad, Abbas. "Steganoflage : A new image steganography algorithm." Thesis, University of Ulster, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506572.
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Wengerhoff, Daniel. "Using the singular value decomposition for image steganography." [Ames, Iowa : Iowa State University], 2006.
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Soukal, David. "Advanced steganographic and steganalytic methods in the spatial domain." Diss., Online access via UMI:, 2006.
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Poremba, Tomáš. "Digitální steganografie a stegoanalýza." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2018. http://www.nusl.cz/ntk/nusl-385979.
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This thesis deals with digital steganography and steganalysis. It explains the significance of both disciplines and gives a brief overview of the history in the given fields. The paper separates existing steganographic and steganalytic methods and describes the attributes of various branches of steganography. With respect to the chosen field of steganography (the image steganography), the paper narrows down the set of suitable steganographic and steganalytic methods, whose features are then described in detail. The results of the thesis inlcude experiments that verify the features of chosen steganographic methods and evaluation of steganalytic methods and their success in detection of steganography.
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Rontauroli, Matteo. "Soluzioni di Deep Learning in ambito di Image Steganography." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20485/.
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La steganografia è la pratica del nascondere un messaggio segreto all’interno di una comunicazione ordinaria. Le sfide in tal senso sono legate ad un’immissione del messaggio che permetta al destinatario di decodificarlo e che allo stesso tempo non sia sospettabile da una parte terza. Nel caso di questo lavoro viene considerata l’incorporazione del messaggio all’interno di immagini, in particolare per due differenti casi, attraverso tecniche di Deep Learning. Nel primo il messaggio segreto è un’immagine delle stesse dimensioni di quella nella quale deve essere incorporata e la trasmissione è digitale. Vengono proposte in questo lavoro due soluzioni al problema, definite principalmente da due differenti architetture di reti neurali e una componente di correlazione per la funzione di loss. Nel secondo caso viene invece considerato il contesto della trasmissione fisica dell’immagine contenente il messaggio (di dimensione inferiore rispetto al caso precedente), dove quest’ultima subisce distorsioni prima di essere ricevuta. Vengono quindi testate e sperimentate differenti soluzioni a quest’ultimo problema, partendo da approcci della letteratura con proposte di cambiamenti per questi. Gli ultimi esperimenti in particolare permettono di estrarre il messaggio da immagini molto piccole e con significative sfocature in contesti non digitali.
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JOHANSSON, SIMON, and EMIL LENNGREN. "Steganographic embedding and steganalysisevaluation : An evaluation of common methods for steganographic embedding and analysis indigital images." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-157499.
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Steganography is the technique that hides secret messages in seemingly inoccuous data. Steganalysis is the technique that is used to discover the use of steganography. Usuallyit is difficult to extract the exact hidden message because itis usually encrypted. Though often it is enough to merely uncover the use of steganography to reveal important information.In this report we discuss some common methods for steganography in images, as well as some methods of analysis,both general and targeted towards specific methods. We test how well the methods fare against each other and what one should consider when making use of steganography. According to our results, many steganographic methods need targeted analysis attacks to be discovered. Our advice is to avoid using the full potential capacity when embeddingdata. The hidden data should also be distributed randomly in the cover file.
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Koppola, Rajanikanth Reddy. "A High Capacity Data-Hiding Scheme in LSB-Based Image Steganography." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1236708072.
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Chandrababu, Aron. "Using an Ariticial Neural Network to Detect the Presence of Image Steganography." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1237343521.
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Hassanein, Mohamed Sameh. "Secure digital documents using Steganography and QR Code." Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/10619.
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With the increasing use of the Internet several problems have arisen regarding the processing of electronic documents. These include content filtering, content retrieval/search. Moreover, document security has taken a centre stage including copyright protection, broadcast monitoring etc. There is an acute need of an effective tool which can find the identity, location and the time when the document was created so that it can be determined whether or not the contents of the document were tampered with after creation. Owing the sensitivity of the large amounts of data which is processed on a daily basis, verifying the authenticity and integrity of a document is more important now than it ever was. Unsurprisingly document authenticity verification has become the centre of attention in the world of research. Consequently, this research is concerned with creating a tool which deals with the above problem. This research proposes the use of a Quick Response Code as a message carrier for Text Key-print. The Text Key-print is a novel method which employs the basic element of the language (i.e. Characters of the alphabet) in order to achieve authenticity of electronic documents through the transformation of its physical structure into a logical structured relationship. The resultant dimensional matrix is then converted into a binary stream and encapsulated with a serial number or URL inside a Quick response Code (QR code) to form a digital fingerprint mark. For hiding a QR code, two image steganography techniques were developed based upon the spatial and the transform domains. In the spatial domain, three methods were proposed and implemented based on the least significant bit insertion technique and the use of pseudorandom number generator to scatter the message into a set of arbitrary pixels. These methods utilise the three colour channels in the images based on the RGB model based in order to embed one, two or three bits per the eight bit channel which results in three different hiding capacities. The second technique is an adaptive approach in transforming domain where a threshold value is calculated under a predefined location for embedding in order to identify the embedding strength of the embedding technique. The quality of the generated stego images was evaluated using both objective (PSNR) and Subjective (DSCQS) methods to ensure the reliability of our proposed methods. The experimental results revealed that PSNR is not a strong indicator of the perceived stego image quality, but not a bad interpreter also of the actual quality of stego images. Since the visual difference between the cover and the stego image must be absolutely imperceptible to the human visual system, it was logically convenient to ask human observers with different qualifications and experience in the field of image processing to evaluate the perceived quality of the cover and the stego image. Thus, the subjective responses were analysed using statistical measurements to describe the distribution of the scores given by the assessors. Thus, the proposed scheme presents an alternative approach to protect digital documents rather than the traditional techniques of digital signature and watermarking.
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Guruswamy, Aarumugam Bhupathi Rajan. "Independent Domain of Symmetric Encryption using Least SignificantBit : Computer Vision, Steganography and Cryptography Techniques." Thesis, Högskolan Dalarna, Datateknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:du-10063.
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The rapid development of data transfer through internet made it easier to send the data accurate and faster to the destination. There are many transmission media to transfer the data to destination like e-mails; at the same time it is may be easier to modify and misuse the valuable information through hacking. So, in order to transfer the data securely to the destination without any modifications, there are many approaches like cryptography and steganography. This paper deals with the image steganography as well as with the different security issues, general overview of cryptography, steganography and digital watermarking approaches. The problem of copyright violation of multimedia data has increased due to the enormous growth of computer networks that provides fast and error free transmission of any unauthorized duplicate and possibly manipulated copy of multimedia information. In order to be effective for copyright protection, digital watermark must be robust which are difficult to remove from the object in which they are embedded despite a variety of possible attacks. The message to be send safe and secure, we use watermarking. We use invisible watermarking to embed the message using LSB (Least Significant Bit) steganographic technique. The standard LSB technique embed the message in every pixel, but my contribution for this proposed watermarking, works with the hint for embedding the message only on the image edges alone. If the hacker knows that the system uses LSB technique also, it cannot decrypt correct message. To make my system robust and secure, we added cryptography algorithm as Vigenere square. Whereas the message is transmitted in cipher text and its added advantage to the proposed system. The standard Vigenere square algorithm works with either lower case or upper case. The proposed cryptography algorithm is Vigenere square with extension of numbers also. We can keep the crypto key with combination of characters and numbers. So by using these modifications and updating in this existing algorithm and combination of cryptography and steganography method we develop a secure and strong watermarking method. Performance of this watermarking scheme has been analyzed by evaluating the robustness of the algorithm with PSNR (Peak Signal to Noise Ratio) and MSE (Mean Square Error) against the quality of the image for large amount of data. While coming to see results of the proposed encryption, higher value of 89dB of PSNR with small value of MSE is 0.0017. Then it seems the proposed watermarking system is secure and robust for hiding secure information in any digital system, because this system collect the properties of both steganography and cryptography sciences.
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Giarimpampa, Despoina. "Blind Image Steganalytic Optimization by using Machine Learning." Thesis, Högskolan i Halmstad, Akademin för informationsteknologi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-38150.
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Since antiquity, steganography has existed in protecting sensitive information against unauthorized unveiling attempts. Nevertheless, digital media’s evolution, reveals that steganography has been used as a tool for activities such as terrorism or child pornography. Given this background, steganalysis arises as an antidote to steganography. Steganalysis can be divided into two main approaches: universal – also called blind – and specific. Specific methods request a previous knowledge of the steganographic technique under analysis. On the other hand, universal methods which can be widely practiced in a variety of algorithms, are more adaptable to real-world applications. Thus, it is necessary to establish even more accurate steganalysis techniques capable of detecting the hidden information coming from the use of diverse steganographic methods. Considering this, a universal steganalysis method specialized in images is proposed. The method is based on the typical steganalysis process, where feature extractors and classifiers are used. The experiments were implemented on different embedding rates and for various steganographic techniques. It turns out that the proposed method succeeds for the most part, providing dignified results on color images and promising results on gray-scale images.
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Кучма, Олександр Русланович, and Oleksandr Kuchma. "Розроблення модуля забезпечення приховування даних на основі стеганографічного методу найменш значущого біту." Master's thesis, ТНТУ, 2021. http://elartu.tntu.edu.ua/handle/lib/36794.
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Розроблення модуля забезпечення приховування даних на основі
стеганографічного методу найменш значущого біту // Дипломна робота ОР
«Магістр» // Кучма Олександр Русланович // Тернопільський національний
технічний університет імені Івана Пулюя, факультет комп’ютерно-
інформаційних систем і програмної інженерії, кафедра кібербезпеки, група
СБм-61 // Тернопіль, 2019 // С. 93, рис. – 34 , табл. – 26 , додат. – 5.Пояснювальна записка містить результати розроблення модуля «Вбудовування інформації в зображенні методом найменш значущого біту». Проведено аналіз предметної області, розроблені моделі бізнес-процесів об’єкта проектування, розроблені специфікації бізнес-вимог, функціональних та не функціональних вимог, спроектовані логічна та фізична моделі бази даних. Виконаний математичний опис задачі для вирішення на ПК та розроблений додаток за допомогою середовища програмування Microsoft Visual Studio 2010. Наведені результати тестування програмного продукту та вимоги щодо його розгортання. Результати роботи можуть бути використані для підтвердження авторського права, для приховування інформації в цифрових зображеннях.
Explanatory note contains the results of the development module "Embedding information in an image using the least significant bit. The analysis domain, the model business processes of the project, developed the specification of business requirements, functional and non functional requirements, designed logical and physical database models. The mathematical description of the problem for solution on the PC application developed using the programming environment Microsoft Visual Studio 2010. The results of software testing and requirements for its deployment. The results may be used to confirm the copyright for hiding information in digital images.
ПЕРЕЛІК УМОВНИХ СКОРОЧЕНЬ ... 7 ВСТУП ... 8 РОЗДІЛ 1... 10 1.1 Коротка характеристика підприємства... 10 Базою підприємства виступає Інтернет-магазин «TradeBox»... 10 1.2 Аналіз предметної області ... 11 Заголовки ... 13 Потоковий контейнер ... 13 Фіксований контейнер ... 13 1.3. Аналіз існуючого програмного продукту, що реалізують функцію предметної області ... 16 РОЗДІЛ 2... 21 2.1. Глосарій проекту ... 21 2.2. Розроблення варіанту використання ... 23 2.2.1. Розроблення діаграми варіантів використання. ... 24 2.2.2. Специфікація варіантів використання ... 25 2.2.3. Розкадровка варіантів використання ... 34 2.3. Специфікація функціональних і не функціональних вимог ... 42 РОЗДІЛ 3... 46 3.1 Математична постановка задачі ... 46 3.2. Проектування структури бази даних ... 50 3.3. Опис архітектури додатку. ... 52 3.3.1 Розроблення діаграми класів, що реалізують бізнес-логіку програмної системи. ... 52 3.3.2. Розроблення діаграми використання елементів графічного інтерфейсу користувача. ... 53 3.4. Тестування додатку. ... 53 3.5. Розгортання програмного продукту. ... 55 3.5.1. Системні мінімальні характеристики ... 55 3.5.2. Вимоги до програмного забезпечення клієнтської частини. ... 55 3.5.3. Спосіб виклику програми, запуск програми. ... 56 РОЗДІЛ 4 ОХОРОНА ПРАЦІ ТА БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІЯХ ... 57 4.1 Охорона праці ... 57 4.2 Підвищення стійкості роботи об'єктів господарської діяльності в воєнний час... 59 СПИСОК ВИКОРИСТАНИХ ДЖЕРЕЛ ... 65 ДОДАТКИ ... 66 ДОДАТОК А ... 67 ДОДАТОК Б ... 69 ДОДАТОК В ... 91 ДОДАТОК Д ... 92 ДОДАТОК Е ... 93
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Stensmar, Isak. "Steganografi i bilder : En studie om bildformat och visuella bildrepresentationens påverkan vid lagring av data med hjälp av en steganografisk metod." Thesis, Blekinge Tekniska Högskola, Institutionen för datalogi och datorsystemteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-12887.
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Sammanhang. Genom att använda steganografi i bilder är det möjligt att lagra en stor mängd data utan att påverka bilden som information lagras i. En vanlig metod som används inom steganografi är LSB (Least Significant Bit), som ofta anses vara en av de första metoderna som användes inom steganografi. Förutom valet av metod har personen ett val att göra när hen ska välja en bild som ska representera bärare av information. Vad man ofta försöker åstadkomma är att skapa en komplex metod men glömmer bort bilden som ska användas som bärare. I slutändan är det bilden som kommer att användas och testas vid olika mätningar. Mål. Den här studien kommer att undersöka om olika typer av bildformat, BMP, PNG, JPEG och TIFF, har någon påverkan när jämförelse görs av originalbilden och den modifierade, givet att en steganografisk metod används för att lagra informationen. Studien kommer även att undersöka om bildrepresentationen har någon påverkan på mätningarna. Metod. En utbyggd metod av Least Significant Bit metoden kommer att implementeras och användas för att lagra information i olika typer av bilder med olika bildformat. Ett experiment sätts upp för att undersöka formaten med hjälp av mätningsverktygen MSE (Mean Squared Error), PSNR (Peek Signal-to-Noise Ratio) och SSIM (Structural Similarity). Resultat. Vid jämförelse av de grafer och tabeller som togs fram, sågs JPEG ha ett bättre resultat genom att ha ett lägre differentiellt värde mellan varje test. BMP, PNG och TIFF hade minimala skillnader mellan varandra för varje test. För bildrepresentationen visade två bilder högre differentiellt värde än de resterande tre. Sammanfattning. Resultaten från experimentet visade att vilken komprimeringsmetod som ett bildformat använder kommer ha påverkan på mätningsvärdena. Resultaten visade också att bildrepresentation kan ha en påverkan på mätningarna av en bild men mer data behövs för att dra en slutsats.Context. By using image steganography it is possible to hide a large amount of data without making big differences to the initial picture. One commonly used method is Least Significant Bit (LSB), which often is considered one of the first method implemented and used in Image Steganography. Apart from the method, the user also have a choice when deciding what picture he or she should use as the carrier of information. What people often try to accomplish is to have a very complex method that hides the data in an efficient way, but forgets about the picture used as a carrier. In the end, all measurements will be done on the picture. Objectives. This study will investigate if different image formats, BMP, PNG, JPEG and TIFF, have an impact on the differences when comparing the original picture with the modified, given that data is stored with a steganographic method and is gradually increased. The study will also investigate if what the picture visually represent will have an effect on the measurements. Methods. An extended method of the Least Significant Bit method will be implemented and used to create different pictures with different kinds of image formats. An experiment will investigate these formats by taking measurements with MSE (Mean Squared Error), PSNR (Peek Signal-to-Noise Ratio) and SSIM (Structural Similarity). Results. When comparing different formats one could say that JPEG showed better performance by having a lower differential value between each test, by looking at the graphs and tables. BMP, PNG and TIFF had minimal changes between each other for each test. As for the visual representation of the pictures, two pictures showed a higher differential value after each test than the remaining three. Conclusions. The results from the experiment showed that which compression method a format uses will have an impact on the measurement. The results also showed that the pictures’ visual representation could have some impact on the measurement of a picture but more data is needed to conclude this theory.
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Currie, Daniel L. Campbell Hannelore. "Implementation and efficiency of steganographic techniques in bitmapped images and embedded data survivability against lossy compression schemes." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA311535.
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Thesis (M.S. in Computer Science) Naval Postgraduate School, March 1996.Thesis advisor(s): Cynthia E. Irvine, Harold Fredricksen. "March 1996." Includes bibliography references (p. 37). Also available online.
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Currie, Daniel L., and Hannelore Campbell. "Implementation and efficiency of steganographic techniques in bitmapped images and embedded data survivability against lossy compression schemes." Thesis, Monterey, California. Naval Postgraduate School, 1996. http://hdl.handle.net/10945/8501.
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Approved for public release; distribution is unlimitedThe term steganography is descriptive of techniques used to covertly communicate by embedding a secret message within an overt message. Such techniques can be used to hide data within digital images with little or no visible change in the perceived appearance of the image and can be exploited to covertly export sensitive information. This thesis explores the data capacity of bitmapped image files and the feasibility of devising a coding technique which can protect embedded data from the deleterious effects of lossy compression. In its simplest form, steganography in images is accomplished by replacing the least significant bits of the pixel bytes with the data to be embedded. Since images are frequently compressed for storage or transmission, it is desirable that a steganographic technique include some form of redundancy coding to counter the errors caused by lossy compression algorithms. Specifically, the Joint Photographic Expert Group (JPEGi) compression algorithm, while producing only a small amount of visual distortion, introduces a relatively large number of errors in the bitmap data. These errors will effectively garble any noncoded steganographically embedded data
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Morkus, Filip. "Program pro skrývání dat v obrazových souborech." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-218835.
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In my master's thesis I start fromthedescriptionofthebasics and thebeginningsofsteganography, itsmethods and purposes. Detaileddescriptionof BMP fileswithhidden data follows. A filestructureisanalysedintothesmallestdetails to avoiddamagingfilewhilehiding. At thesametime to make profit oftheinformationincluded in a fileheader in the most effectiveway. Anotheraimwas to explain a principalofsteganographicalmethoditself, usedforhiding data into BMP file. Based on these findings, a programmeconceptwasdesigned and consequentlythatprogrammewas made. Itcarriesoutthehiding and revealing data intothe image files. Directionsfor use are made to thisprogramme and thereisalso a demo ofthefeaturesdescribingeach step. At the end ofmymaster's thesis anattentionispaid to thoseinfluencesthatcanbelimitingforthismethod. Exceeding these limitswouldlead to breakingthesteganographicalmethod, whichmeansrevealingthehidden data.
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Oliveira, Fábio Borges de. "Análise de segurança em criptografia e esteganografia em sequências de imagens." Laboratório Nacional de Computação Científica, 2007. https://tede.lncc.br/handle/tede/63.
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Information security is being considered of great importance to the private and governamental institutions. For this reason, we opted to conduct a study of security in this dissertation. We started with an introduction to the information theory, and then we proposed a new kind of Perfect Secrecy cryptographic and finally made a study of steganography in an image sequence, in which we suggest a more aggressive steganography in coefficients of the discrete cosine transform.
A segurança da informação vem sendo considerada de grande importância para as instituições privadas e governamentais. Por este motivo, optamos em realizar um estudo sobre segurança nesta dissertação. Iniciamos com uma introdução à teoria da informação, partimos para métodos de criptografia onde propomos um novo tipo de Segredo Perfeito e finalmente fazemos um estudo de esteganografia em uma sequência de imagens, onde propomos uma esteganografia mais agressiva nos coeficientes da transformada discreta de cosseno.
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Azevedo, Samuel Oliveira de. "Sistema de agentes polig?nicos para estegan?lise de imagens digitais." Universidade Federal do Rio Grande do Norte, 2007. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17965.
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Previous issue date: 2007-08-06Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
In this work, we propose a multi agent system for digital image steganalysis, based on the poliginic bees model. Such approach aims to solve the problem of automatic steganalysis for digital media, with a case study on digital images. The system architecture was designed not only to detect if a file is suspicious of covering a hidden message, as well to extract the hidden message or information regarding it. Several experiments were performed whose results confirm a substantial enhancement (from 67% to 82% success rate) by using the multi-agent approach, fact not observed in traditional systems. An ongoing application using the technique is the detection of anomalies in digital data produced by sensors that capture brain emissions in little animals. The detection of such anomalies can be used to prove theories and evidences of imagery completion during sleep provided by the brain in visual cortex areas
Neste trabalho, propomos um sistema multi-agentes para estegan?lise em imagens digitais, baseado na met?fora das abelhas polig?nicas. Tal abordagem visa resolver o problema da estegan?lise autom?tica de m?dias digitais, com estudo de caso para imagens digitais. A arquitetura do sistema foi projetada n?o s? para detectar se um arquivo ? ou n?o suspeito de possuir uma mensagem oculta em si, como tamb?m para extrair essa mensagem ou informa??es acerca dela. Foram realizados v?rios experimentos cujos resultados confirmam uma melhoria substancial (de 67% para 82% de acertos) com o uso da abordagem multi-agente, fato n?o observado em outros sistemas tradicionais. Uma aplica??o atualmente em andamento com o uso da t?cnica ? a detec??o de anomalias em dados digitais produzidos por sensores que captam emiss?es cerebrais em pequenos animais. A detec??o de tais anomalias pode ser usada para comprovar teorias e evidencias de complementa??o do imageamento durante o sono, provida pelo c?rebro nas ?reas visuais do c?rtex cerebral
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Pacura, Dávid. "Neviditelné značení digitálních signálů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-240846.
Full textAbstract:
Cílem téhle práce je navrhnutí nových technik pro robustní neviditelné značení digitálních signálů. Nejdříve je prezentován současný stav tohoto odvětví a dostupné softwarové řešení. Poté následuje návrh několika algoritmů pro neviditelné značení, přičemž každý z nich je založen na jiném principu. Dále je připravena sada digitálních testovacích signálů společně s testovacím softwarem pro otestování navržených řešení a jejích porovnání s vybraným dostupným softwarem. Poté následuje srovnání naměřených výsledků, výkonu a jejích diskuze.
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Chin-Te, Chien, and 簡進德. "Lossless image sharing with Steganography and Authentication for multiple secret images." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/98966098053717735892.
Full textAbstract:
碩士明新科技大學
資訊管理研究所
97
Secret image sharing can effectively avoid the problem that an original image cannot be reconstructed due to the modification of a single ciphertext. However, shadow images are noise-like so might draw attackers’ attention; meanwhile, they may still be modified incidentally or intentionally by participants. To resolve these problems, it was proposed to embed shadow images in preselected meaningful images (cover images) with LSB substitution, and authenticate stego images with one-bit authentication code. Nevertheless, it is inconvenient for managers of multiple secret images because they need to have multiple copies of shadow images. A universal share concept was proposed to improve the convenience of management; however, when embedding a universal image, this mechanism induces distortion to the original images. Therefore, it is not appropriated for those applications which cannot tolerate image distortion (e.g., medical sciences, military, etc.). Hence, we integrate those previous mechanisms and resolve the following three problems: (1). Distortion problem: we expand the original secret image to become times of itself in order to keep the original image intact while embedding a universal image. Moreover, this study employs the Galois Field GF(28) to perform modular arithmetic operations in sharing polynomials. (2). Authentication strength: authentication code is upgraded from one-bit to four-bit so that the authentication strength of shadow images can be effectively improved. (3). Image quality problem: a four-bit authentication code may reduce the image quality. We use a new date hiding mechanism to embed both the shares and the authentication code to improve the quality. The experimental results show that: (1). the proposed mechanism can effectively reconstruct the original image without distortion; (2). the probability that a fake block of a stego image is successfully authenticated can be largely improved to 15/16; (3). the authentication ability is strengthened with good visual quality of stego images.
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kanagi, Karamo, and 卡拉莫. "Steganography by Color Images Using Advanced Encryption Standard (AES)." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/72471940294150032343.
Full textAbstract:
碩士國立清華大學
資訊系統與應用研究所
103
資訊安全近期在資料通訊中佔有很大的重要議題。其中，影像藏密及密碼學都是確保祕密訊息的方法。影像藏密是把一張訊息藏在數位媒體並且遮掩一些資訊。但是如果分開使用這些技術，並沒有辦法完整的保護資訊安全。為了要保護資訊安全及機密資訊，我們必須結合影像藏密及密碼學去提供更強大的資訊通訊來防止入侵者。 在這篇論文中，我們提供一個影像藏密的方法去專注在24位元的彩色影像。這項方法使用了標籤圖像文件格式，並且在使用最低有效位（LSB）方法的圖像嵌入裡面，使用AES 128位元的加密算法的秘密信息進行加密，透過減少到封面圖像所做的更改量來提高LSB的方法。在這項實驗中，比較分析了通過計算均方誤差（MSE）和峰值信噪比（PSNR）證明了該方法的有效性。最後的結果顯示此方法能保持圖像質量和安全的更高的水平。
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Chen, Chin Kuang, and 陳勤廣. "A Novel Steganography Using Hill Cipher and Microarray Images." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/44579276195478075474.
Full textAbstract:
碩士國立清華大學
資訊系統與應用研究所
104
With the rapid development of technology, Internet has become possible to communicate and transmit any type of data across networks. Security of data or information has become a critical issue in data storage and transmission to prevent attacks from accessing personal information and other types of data such as credit card numbers. Steganography refers to the technique of hiding information in digital media in order to conceal the existence of the information. In this thesis, we use microarray image, Hill cipher algorithm and least significant bits substitution to implement steganography. Because of the advantage of the microarray images, we can perform the four bits LSB replacement method easily to embed the secret message. Moreover, our proposed system is not limited to files format of secret message.
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Huang, Ching-Huan, and 黃景煥. "A Steganography Method by Block Analysis in Gray Level Images." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/76888683254500885591.
Full textAbstract:
碩士國立清華大學
資訊工程學系
93
We have proposed a novel and secure steganographic method for embedding secret data into a gray scale image in this thesis. In the embedding process, the image is partitioned into non-overlapping blocks. The pixels in a block are classified into unchangeable pixels and changeable pixels. The average of the gray values of unchangeable pixels in each block is calculated as . The embedded amount of data for each changeable pixel is determined by the difference between and the gray value of the changeable pixel. A larger difference embeds a higher amount of secret data. We modify the gray value of a changeable pixel and reset a new gray value with secret data embedded. But, not all the changeable pixels are appropriated for embedding secret data. The gray values of some changeable pixels may cause wrong extraction if they were used in embedding. We have two fault potential checking processes which execute both embedding procedure and extracting procedure to automatically detect and discard fault potential changeable pixels. Therefore, no extra space is needed for recording the positions of the fault potential changeable pixels. The experimental results show that we can embed secret data into an image without noticeable distortion.
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Huang, Pei Lin, and 黃佩琳. "Steganography Using Biometric Images and Linear Feedback Shift Register (LFSR)." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/38818826188942863931.
Full textAbstract:
碩士國立清華大學
資訊系統與應用研究所
104
Steganography and cryptography are techniques that try to protect message from being captured during data transmission. Algorithms which combined steganography and cryptography can provide a higher security. In this thesis, we propose a least significant bit (LSB) based steganography. In order to enhance the security, we use linear feedback shift register (LFSR) to generate random sequences to do exclusive-or (XOR) operations with the secret message and then embed the ciphered message into biometric images. In the capacity aspect, our algorithm can support up to four least significant bits (4LSB) replacement according to the size of message. The effectiveness of the proposed method is estimated by peak signal-to-noise ratio (PSNR), embedding rate and execution time. The results show that high PSNR values with short execution time is feasible.
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(7036661), Min Huang. "Statistical Steganalysis of Images." Thesis, 2019.
Find full textAbstract:
Steganalysis is the study of detecting secret information hidden in objects such as
images, videos, texts, time series and games via steganography. Among those objects,
the image is the most widely used object to hide secret messages. Detection of possible
secret information hidden in images has attracted a lot of attention over the past ten
years. People may conduct covert communications by exchanging images in which
secret messages may be embedded in bits. One of main advantages of steganography
over cryptography is that the former makes this communication insensible for human
beings. So statistical methods or tools are needed to help distinguish cover images
from stego images.
In this thesis, we start with a discussion of image steganography. Different kinds
of embedding schemes for hiding secret information in images are investigated. We
also propose a hiding scheme using a reference matrix to lower the distortion caused
by embedding. As a result, we obtain Peak Signal-to-Noise Ratios (PSNRs) of stego
images that are higher than those given by a Sudoku-based embedding scheme. Next,
we consider statistical steganalysis of images in two different frameworks. We first
study staganalysis in the framework of statistical hypothesis testing. That is, we
cast a cover/stego image detection problem as a hypothesis testing problem. For this
purpose, we employ different statistical models for cover images and simulate the
effects caused by secret information embedding operations on cover images. Then
the staganalysis can be characterized by a hypothesis testing problem in terms of
the embedding rate. Rao’s score statistic is used to help make a decision. The
main advantage of using Rao’s score test for this problem is that it eliminates an assumption used in the previous work where approximated log likelihood ratio (LR)
statistics were commonly employed for the hypothesis testing problems.
We also investigate steganalysis using the deep learning framework. Motivated
by neural network architectures applied in computer vision and other tasks, we propose a carefully designed a deep convolutional neural network architecture to classify the cover and stego images. We empirically show the proposed neural network
outperforms the state-of-the-art ensemble classifier using a rich model, and is also
comparable to other convolutional neural network architectures used for steganalysis.
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Tsai, Ya-Chun, and 蔡雅純. "The Study of Digital Watermarking and Steganography Techniques for Fractal Compression Images." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/39579758464947719191.
Full textAbstract:
碩士育達商業技術學院
資訊管理所
96
Information hiding is a technique of hiding secret using redundant cover data such as images, audios, movies, documents, etc. The techniques are used today include watermarking and steganography. The major concern of watermarking is to protect the ownership of a digital content, while steganography is to embed secret messages into digital content so that the secret messages is not detectable. Recently, plenty of researches focus on information hiding in digital images. The fractal compression is one of image compression techniques with high compression rate. This technique compresses original image into codes of iterated function systems based on the properties of self-similarities and iterations. In the decoding stage, an arbitrary image is given as the initial image and the decoded image is repeatedly reconstructed by applying the contractive affine transformation to the original image. In the previous researches, the rule of embedding messages in the fractal compression images usually uses a fixed threshold. Instead, we use an adaptive threshold to contuse both the stego image quality and hiding capacity. In the experimental results, the digital watermarking can be extracted properly under several image destroying operations. In addition, the hiding capacity of the data hiding scheme can be doubled without sacrificing the image quality.
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Tseng, Chiung-Chen, and 曾瓊蓁. "A High Payload Steganography Scheme for Color Images Based on BTC and Hybrid Strategy." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/03826317414928902865.
Full textAbstract:
碩士亞洲大學
資訊工程學系
103
With advances in computer networks and applications, the Internet has become indispensable to delivering confidential data. Information security is a prime concern as people’s use of the Internet increases. Various research studies have been done to better protect data in transit and ensure information security. Cryptographic methods and steganography are the most commonly used strategies to secure communications on the Internet. To compliment cryptographic methods, which do not hide secret data in transmitted packets, steganography is used to embed secret data so that unintended recipients are unaware of the secret data been transmitted in a steganographic image. Therefore, the quality of the stego image must be high for the embedded secret message. In general, information hiding (also called data hiding or data embedding) technique includes digital watermarking and steganography. These information hiding methods are currently used by many researchers for various applications. Embedding capacity is one of the key issues in data hiding research. In theory, a higher embedding capacity in the original medium usually means poorer visual quality. Block Truncation Coding (BTC) is one of the popular compression techniques used in image data hiding because of its low computation cost and ease of implementation. For a color image, there are three pairs of high mean and low mean values with three bitmaps. A common bitmap can be used to reduce the size of the BTC compression code. Chang et al. presented a data hiding method to conceal secret data in the color image BTC compression code by rearranging the encoding sequences of the high mean and low mean values. The proposed method attempts to embed more secret data into the color BTC compression code. In this thesis, a novel method is proposed to encrypt data based on the number of the element ‘1’. If the number is even, the data for the secret bit is ‘0’; otherwise, the secret bit is ‘1’. Furthermore, the Less Significant Bit (LSB) of all high mean and low mean pairs can also be used to embed the secret data. Experimental results show that with the proposed method, each block conceals at least 10 secret bits while good visual quality is maintained.
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施宣光. "Reversible Steganography for BTC-compressed Images Based on Information Encoding and Joint Neighboring Coding." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/69854057230916163759.
Full textAbstract:
碩士國立彰化師範大學
資訊工程學系
102
Recently, reversible steganography becomes a popular research issue. More and more attention have been paid to reversible data hiding techniques for compressed images based on Vector Quantization(VQ),JPEG, and Block Truncation Coding(BTC),because it can recover both the host media and hidden data without distortion. Compared with other compressed method, BTC has a significantly low complexity and less memory requirement, it therefore becomes an ideal data hiding domain. Reversible information hiding is a technique that can restore the stego-media after extracting all the classified messages. Due to the high correlativity with adjacent pixels, a natural image usually contains several smooth regions. In this paper, we proposed a data hiding scheme to embed secret data in the compressed bit streams. Use the bitmap substituting and reconstructed levels replacing and information encoding to hide data in the compressed gray images. And finally we combine the joint neighboring coding technique to hide more information The experimental results show that the proposed method outperforms the previous methods in embedding capacity.
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Suresh, V. "Image Structures For Steganalysis And Encryption." Thesis, 2010. https://etd.iisc.ac.in/handle/2005/2273.
Full textAbstract:
In this work we study two aspects of image security: improper usage and illegal access of images. In the first part we present our results on steganalysis – protection against improper usage of images. In the second part we present our results on image encryption – protection against illegal access of images.
Steganography is the collective name for methodologies that allow the creation of invisible –hence secret– channels for information transfer. Steganalysis, the counter to steganography, is a collection of approaches that attempt to detect and quantify the presence of hidden messages in cover media.
First we present our studies on stego-images using features developed for data stream classification towards making some qualitative assessments about the effect of steganography on the lower order bit planes(LSB) of images. These features are effective in classifying different data streams. Using these features, we study the randomness properties of image and stego-image LSB streams and observe that data stream analysis techniques are inadequate for steganalysis purposes. This provides motivation to arrive at steganalytic techniques that go beyond the LSB properties. We then present our steganalytic approach which takes into account such properties.
In one such approach, we perform steganalysis from the point of view of quantifying the effect of perturbations caused by mild image processing operations–zoom-in/out, rotation, distortions–on stego-images. We show that this approach works both in detecting and estimating the presence of stego-contents for a particularly difficult steganographic technique known as LSB matching steganography.
Next, we present our results on our image encryption techniques. Encryption approaches which are used in the context of text data are usually unsuited for the purposes of encrypting images(and multimedia objects) in general. The reasons are: unlike text, the volume to be encrypted could be huge for images and leads to increased computational requirements; encryption used for text renders images incompressible thereby resulting in poor use of bandwidth. These issues are overcome by designing image encryption approaches that obfuscate the image by intelligently re-ordering the pixels or encrypt only parts of a given image in attempts to render them imperceptible. The obfuscated image or the partially encrypted image is still amenable to compression. Efficient image encryption schemes ensure that the obfuscation is not compromised by the inherent correlations present in the image. Also they ensure that the unencrypted portions of the image do not provide information about the encrypted parts. In this work we present two approaches for efficient image encryption.
First, we utilize the correlation preserving properties of the Hilbert space-filling-curves to reorder images in such a way that the image is obfuscated perceptually. This process does not compromise on the compressibility of the output image. We show experimentally that our approach leads to both perceptual security and perceptual encryption. We then show that the space-filling curve based approach also leads to more efficient partial encryption of images wherein only the salient parts of the image are encrypted thereby reducing the encryption load.
In our second approach, we show that Singular Value Decomposition(SVD) of images is useful from the point of image encryption by way of mismatching the unitary matrices resulting from the decomposition of images. It is seen that the images that result due to the mismatching operations are perceptually secure.
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Suresh, V. "Image Structures For Steganalysis And Encryption." Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/2273.
Full textAbstract:
In this work we study two aspects of image security: improper usage and illegal access of images. In the first part we present our results on steganalysis – protection against improper usage of images. In the second part we present our results on image encryption – protection against illegal access of images.
Steganography is the collective name for methodologies that allow the creation of invisible –hence secret– channels for information transfer. Steganalysis, the counter to steganography, is a collection of approaches that attempt to detect and quantify the presence of hidden messages in cover media.
First we present our studies on stego-images using features developed for data stream classification towards making some qualitative assessments about the effect of steganography on the lower order bit planes(LSB) of images. These features are effective in classifying different data streams. Using these features, we study the randomness properties of image and stego-image LSB streams and observe that data stream analysis techniques are inadequate for steganalysis purposes. This provides motivation to arrive at steganalytic techniques that go beyond the LSB properties. We then present our steganalytic approach which takes into account such properties.
In one such approach, we perform steganalysis from the point of view of quantifying the effect of perturbations caused by mild image processing operations–zoom-in/out, rotation, distortions–on stego-images. We show that this approach works both in detecting and estimating the presence of stego-contents for a particularly difficult steganographic technique known as LSB matching steganography.
Next, we present our results on our image encryption techniques. Encryption approaches which are used in the context of text data are usually unsuited for the purposes of encrypting images(and multimedia objects) in general. The reasons are: unlike text, the volume to be encrypted could be huge for images and leads to increased computational requirements; encryption used for text renders images incompressible thereby resulting in poor use of bandwidth. These issues are overcome by designing image encryption approaches that obfuscate the image by intelligently re-ordering the pixels or encrypt only parts of a given image in attempts to render them imperceptible. The obfuscated image or the partially encrypted image is still amenable to compression. Efficient image encryption schemes ensure that the obfuscation is not compromised by the inherent correlations present in the image. Also they ensure that the unencrypted portions of the image do not provide information about the encrypted parts. In this work we present two approaches for efficient image encryption.
First, we utilize the correlation preserving properties of the Hilbert space-filling-curves to reorder images in such a way that the image is obfuscated perceptually. This process does not compromise on the compressibility of the output image. We show experimentally that our approach leads to both perceptual security and perceptual encryption. We then show that the space-filling curve based approach also leads to more efficient partial encryption of images wherein only the salient parts of the image are encrypted thereby reducing the encryption load.
In our second approach, we show that Singular Value Decomposition(SVD) of images is useful from the point of image encryption by way of mismatching the unitary matrices resulting from the decomposition of images. It is seen that the images that result due to the mismatching operations are perceptually secure.
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Tu, Shu-Fen, and 杜淑芬. "On the design of protection scheme for digital images and documents based on visual secret sharing and steganography." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/20149312408849680560.
Full textAbstract:
博士國立中央大學
資訊管理研究所
93
To prevent the confidential information from being disclosed, one needs to apply some techniques to protect it. Visual cryptography scheme is a secret sharing technique, which splits a binary image into n shares, and gathering more than k shares can recover the secret. The remarkable feature of a visual cryptography scheme is that the decoding process is done by human eyes. A conventional visual cryptography scheme encodes a pixel on the secret image into m subpixels on the share hence makes the size of the decoded image larger than that of the secret image. A few of studies pay attention on solving the problem of pixel expansion. Some studies, incorporated with halftoning or probability, can construct a visual cryptography scheme for gray-level images without pixel expansion. However, such integrated schemes seem not suitable because the visual effect of the decoded image is poor. Except for the problem of pixel expansion, the loss of contrast is also a problem for the visual cryptography. Since the secret is decoded visually, making a good visual effect and offsetting the loss of contrast are as important as keeping the image size invariant. In this study, we propose two Multi-pixel Encoding Methods based on the visual cryptography scheme. The main purpose of the proposed method is to solve the problem of pixel expansion and generate smooth-looking decoded images. For each time, we simultaneously encode m pixels, called an encryption sequence, on the secret image into m pixels on the share. Hence the size of the decoded image is the same as that of the secret image. There are two different ways to take an encryption sequence: one is to take m pixels with the same color; the other is to take m adjacent pixels. For the former one, there are two kinds of encryption sequences on a secret image: one is black encryption sequence; the other is white encryption sequence. These two encryption sequences are encoded by black and white basis matrices respectively. For the later one, there are (m + 1) types of encryption sequences on a secret image. We propose two different ways to handle different kinds of encryption sequences. When incorporating with halftoning, we can construct a gray-level visual cryptography scheme with a smooth-looking decoded image. Moreover, we exploit the CMY color model to decompose a chromatic image into three image layers in tones of cyan, magenta, and yellow, respectively. Then, we can use the proposed Multi-pixel Encoding Methods to construct a chromatic visual cryptography scheme without pixel expansion. The experimental results show that the size of shares is the same as that of the secret image, and visual effect of the decoded image look smooth as well. Moreover, our scheme can offset the loss of contrast caused by visual cryptography. Since visual cryptography is not suitable for transferring large amount of texts, we can use Lin and Lee’s document protection scheme to protect the secret message. They randomly choose a meaningful document as a cheating message and then encode a secret message into an index file. The index file is encrypted by IDEA (International Data Encryption Algorithm) before they are sent out. However, the content of the cheating document is restricted to the secret message, i.e. the selection of the cheating message is not truly random; therefore, they can not use any text as cheating message. Besides, the length of the cheating document cannot be shorter than that of the secret document. In addition, the size of the encoded result – index file – is too large so it must be compressed. Although some researchers proposed slight improvements on Lin and Lee’s scheme, the above major drawbacks of Lin and Lee’s scheme are unsolved. We proposed a new document protection scheme to remedy these drawbacks mentioned above. The first method of our scheme utilizes a subtraction operator to encode the secret message. For each code of the secret message, we randomly pick a code from the cheating message and subtract it from the secret code. The difference is the cipher code of the secret code. The second method of our scheme utilizes a comparison and a logic XOR operator to encode the secret message. For each secret code, we randomly generate a equal-length code from the cheating message via comparison operator. Then we perform logic XOR on the generated code and the secret code. The result is the cipher code of the secret code. The security of the first method mainly depends on the seed of the pseudo random number generator; hence the cipher message may need to be encrypted by another cryptosystem for advancing the security more. The second method possesses the positive features of the first method and conforms to the property of perfect secrecy; hence the cipher message is not necessary to be encrypted again by another cryptosystems. In addition, the experimental results show that the cheating message is not restricted by the secret message. Therefore, the selection of the cheating message is truly random.
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Μπαλκούρας, Σωτήριος. "Στεγανογραφία ψηφιακών εικόνων." Thesis, 2013. http://hdl.handle.net/10889/6438.
Full textAbstract:
Η ανάπτυξη του διαδικτύου τα τελευταία χρόνια έχει φέρει αλλαγές στο μέγεθος και την ποιότητα του διαθέσιμου περιεχομένου. Οι χρήστες κυριολεκτικά κατακλύζονται από πληροφορία η οποία μπορεί να έχει διάφορες μορφές όπως κείμενο, ήχο, εικόνα, βίντεο. Η μεγάλη εξάπλωση του διαδικτύου, η εύκολη αναζήτηση σε μεγάλο όγκο πληροφορίας καθώς και η παρουσίαση του περιεχομένου με φιλικό τρόπο προς το χρήστη συνέβαλε στην ολοένα αυξανόμενη ανάγκη για προμήθεια εικόνων, βίντεο και μουσικής. Η ψηφιοποίηση του μεγαλύτερου όγκου περιεχομένου που διαχειρίζονται οι χρήστες τόσο στην προσωπική όσο και στην επαγγελματική ζωή τους οδήγησε στην ανάπτυξη νέων τεχνικών στεγανογραφίας για την ανταλλαγή κρυφής πληροφορίας, έννοια η οποία είναι ευρέως γνωστή από την αρχαιότητα.
Η παρούσα μεταπτυχιακή εργασία υλοποιεί δύο από τους πιο δημοφιλείς αλγορίθμους στεγανογράφησης τον (Least Significant Bit) και τον LBP (Local Binary Pattern). Το σύστημα που αναπτύχθηκε είναι διαθέσιμο στο διαδίκτυο και μπορεί να χρησιμοποιηθεί από οποιοδήποτε χρήστη επιθυμεί να αποκρύψει πληροφορία (κείμενο ή εικόνα) μέσα σε μια εικόνα. Το σύστημα υλοποιεί όλο τον κύκλο της στεγανογράφησης δίνοντας τη δυνατότητα στο χρήστη όχι μόνο να κάνει απόκρυψη της πληροφορίας που επιθυμεί αλλά και την αντίστροφη διαδικασία δηλαδή την ανάκτηση της κρυμμένης πληροφορίας. Η διαδικασία είναι απλή και απαιτεί από τον αποστολέα (αυτός που κρύβει το μήνυμα) το ανέβασμα της εικόνας στο σύστημα, την εισαγωγή ενός μυστικού κλειδιού το οποίο πρέπει να είναι γνωστό για την ανάκτηση του μηνύματος, και φυσικά το μήνυμα, δηλαδή η προς απόκρυψη πληροφορία. Στη συνέχεια ο παραλήπτης για να ανακτήσει το μήνυμα θα πρέπει να ανεβάσει στο σύστημα τη στεγανογραφημένη εικόνα καθώς και το μυστικό κλειδί που έχει συμφωνήσει με τον αποστολέα.
Τέλος, με κάποια σενάρια χρήσης, πραγματοποιούνται μετρήσεις, οι οποίες δείχνουν την απόδοση κάθε αλγορίθμου και γίνονται οι αντίστοιχες συγκρίσεις. Το σύστημα που υλοποιήθηκε στην παρούσα εργασία μπορεί να συμπεριλάβει και άλλες μεθόδους στεγανογράφησης καθώς επίσης και με την επέκταση του αλγορίθμου LBP ώστε να χρησιμοποιεί και τις τρεις χρωματικές συνιστώσες για την απόκρυψη της πληροφορίας.. Επίσης, θα είχε ιδιαίτερο ενδιαφέρον η παροχή της συγκεκριμένης διαδικασίας σαν ηλεκτρονική υπηρεσία (web service) ώστε να είναι εφικτό να χρησιμοποιηθεί ανεξάρτητα και να μπορεί να εισαχθεί ως αυτόνομο κομμάτι λογισμικού σε κάθε πλατφόρμα που υποστηρίζει web services.The development of the internet in recent years has brought changes in the size and quality of the available content. Users literally flooded with information which may have various forms like text, audio, image, and video. The wide spread of the internet, the ease of search in a large amount of information and the presentation of the available content in a friendly way resulted in the need for more images, videos and music. With the digitization of the available content new steganography techniques were necessary so that users can exchange secret information. In the current thesis two of the most popular steganography algorithms are implemented: the LSB (Least Significant Bit) and the LBP (Local Binary Pattern). The system is publicly available and can be used by any user who wishes to hide information (text or image) within an image. The system provides functionalities so that user can hide information within an image and recover the hidden information. The sender (the person who wishes to hide a message) has to provide the following information in the system: upload the image, provide the secret key needed to retrieve the message, and upload the message. The receiver has to upload the image containing the message and the secret key needed to recover the message. Anumber of usage scenarios are implemented to measure the performance of the algorithms and make comparisons. The implemented system can easily include more steganografy methods and also the extension of the LBP algorithm so that the three color components are used to hide the information. It would be interested to provide the current process as an e-service (web service) that it is feasible to be used independently and can be introduced as a standalone piece of software in any platform that supports web services.
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Huang, Yu-Lin, and 黃郁霖. "Reversible Steganography on Image." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/08377836807386366733.
Full textAbstract:
碩士朝陽科技大學
資訊管理系碩士班
98
Due to the rapid development of information technology and internet, people usually convert a lot of data into digitally. The digital data are also transmitted over the internet. However, internet is a public transmitting channel that the transmitting data may be stolen and distorted by illegal user. Therefore, how to protect data during transmission became an important issue. Data hiding is a technique that allows the secret data embed into a cover image and generate a stego-image. Illegal user does not aware of the secret data which is transmitted with stego-image. The image quality of stego-image has distortion after data embedding. However, in a number of domains such as military, legal and medical…etc., the image distortion is undesirable. Therefore, the reversible data hiding technique is proposed. Reversible data hiding technique not only can embed the secret data but also recover the distortion into original image. However, there are two drawbacks in the reversible data hiding technique. First, the image quality of reversible data hiding technique with high payload is also huge less than the irreversible data hiding technique. Second, reversible data hiding technique requires much additional data for recovering image and extracting secret data. In order to improve the drawbacks of reversible data hiding technique, our research proposed the reversible data hiding schemes base on dual steganography images. Our proposed schemes use a private key to embed the secret data into two stego-images. The receiver must have two stego-images and the private key for restoring original image and extracting secret data currently. For the features above, our research provides further security.
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Wang, Chun-Chieh, and 王俊傑. "High Capacity Binary Image Steganography." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/65410751032931102761.
Full textAbstract:
碩士國立清華大學
資訊工程學系
92
The popularity and availability of multimedia data promote digital communication with steganography. High data capacity and cover image quality maintenance after data embedding are the major requirements in digital image steganography. On the other hand, hiding data in binary images is challenging for the property that each pixel is made up by only one bit. As a result, we present a simple and high capacity binary image steganography. In our method, uniform blocks are utilized to embed data in addition to non-uniform blocks. Two data bits are hidden by at most modifying two pixels in an embeddable image block according to the proposed embedding criteria. The most suitable pixel to be modified is found quickly by simple weighting method when necessary. The experimental results show the excellent performance over other’s mechanism in data capacity and image quality.
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Lee, Yeuan-Kuen, and 李遠坤. "A Study on Image Steganography." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/67186023602190623457.
Full textAbstract:
博士國立交通大學
資訊科學系
90
Steganography is an ancient art of conveying messages in a secret way that only the receiver knows the existence of the message. A classic steganographic model presented by Simmons is the prisoners' problem. In this problem, two persons in the jail plan to make an escape together. All communications between them are monitored by the warden. Therefore, they must hide the messages concerning escape plan in another innocuous-looking media. In this manner, steganography provides another layer of protection on the covert communication. The message is hidden in another media such that the transmitted data will be meaningful and innocuous-looking to everyone. Compared with cryptography attempting to conceal the content of the secret message, steganography conceals the very existence of message. On the other hand, for detecting the covert communication, the warden should analysis all messages sent between prisoners. Steganalysis is the art of detecting secret communication. If the existence of message is reveal, the purpose of steganography will be defeated. In this dissertation, the secret message is embedded in images for protecting the privacy of communication on the Internet. Since the created stego-images can be stored in various formats, we will propose three embedding techniques for covert communication under three different conditions. First, the created stego-images are stored in uncompressed formats. Second, the stego-images are compressed using JPEG standard. Finally, the format of the stego-images can be converted from JPEG to GIF, and vice versa. For analyzing the performance of the proposed steganographic models, three types of steganalysis will be considered: image fidelity, visual attack and statistical attack. Images with hidden message, called the stego-images, should be indistinguishable from their original ones, called the cover-images. Visual attack uses the ability of human eyes to clearly recognize the unusual visual patterns. Some statistical characteristics of natural images can also be used to reliably identify which images contain the hidden message. Using the least significant bit (LSB) embedding method, the hidden message can be reliably detected by using some statistical attacks. In this dissertation, a variable-sized LSB embedding method for uncompressed format will be proposed first. For investigating the maximum payload of each pixel, the number of LSBs used for message embedding depends on the local characteristics, such as luminance and contrast. Since the original bit-plane characteristics can be maintained, the hidden message is undetectable by using the visual attack. Chi-square attack is also used to show that the hidden message is statistically undetectable. Next, we will propose a variation of an information embedding method, called Quantization Index Modulation (QIM), for JPEG images. The proposed method embeds the messages to be conveyed by modifying the mean intensity value of image blocks, and the resulted stego-image can be stored in the JPEG format with a low quality setting. A theorem is also proposed to show that the error of mean intensity value of an image block caused by JPEG compression is bounded. Besides, a specific pattern caused by using QIM embedding method is also identified, and this pattern will be removed using the proposed embedding method. Experimental results and the proposed theorem show that the hidden message is error-free against the JPEG distortion under the quality setting as low as 25. Furthermore, the existence of hidden message is not only visually imperceptible but also statistically undetectable. Finally, we will present a novel idea for exactly extracting the hidden message while the stego-images are stored in various compression formats, such as GIF, JPEG and JPEG 2000 (J2K). The main idea is to embed secret data through distorting a given object and the distorted object still looks natural. Experimental results show that the hidden message can be extracted correctly even the stego-images are stored in various compression formats and rates. Furthermore, the embedded message is robust enough when the stego-image format is converted from one compression format to another one. All of the experimental results show that the proposed embedding techniques meet the fundamental requirement of steganographic system, i.e., undetectability. Therefore, selecting the most suitable technique under various transmission conditions will make the proposed steganographic model more powerful.
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Morkel, Tayana. "Image steganography applications for secure communication." Diss., 2012. http://hdl.handle.net/2263/29906.
Full textAbstract:
To securely communicate information between parties or locations is not an easy task considering the possible attacks or unintentional changes that can occur during communication. Encryption is often used to protect secret information from unauthorised access. Encryption, however, is not inconspicuous and the observable exchange of encrypted information between two parties can provide a potential attacker with information on the sender and receiver(s). The presence of encrypted information can also entice a potential attacker to launch an attack on the secure communication. This dissertation investigates and discusses the use of image steganography, a technology for hiding information in other information, to facilitate secure communication. Secure communication is divided into three categories: self-communication, one-to-one communication and one-to-many communication, depending on the number of receivers. In this dissertation, applications that make use of image steganography are implemented for each of the secure communication categories. For self-communication, image steganography is used to hide one-time passwords (OTPs) in images that are stored on a mobile device. For one-to-one communication, a decryptor program that forms part of an encryption protocol is embedded in an image using image steganography and for one-to-many communication, a secret message is divided into pieces and different pieces are embedded in different images. The image steganography applications for each of the secure communication categories are discussed along with the advantages and disadvantages that the applications have over more conventional secure communication technologies. An additional image steganography application is proposed that determines whether information is modified during communication. CopyrightDissertation (MSc)--University of Pretoria, 2013.
Computer Science
unrestricted
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Wu, Yi-Ta. "Image watermarking, steganography, and morphological processing." Thesis, 2005. http://library1.njit.edu/etd/fromwebvoyage.cfm?id=njit-etd2005-087.
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