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1	Statistical Steganalysis of Images Min Huang (7036661) 13 August 2019 (has links) <div>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. <br></div><div><br></div><div>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.<br></div><div><br></div><div>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.<br></div><div><br></div>The image databases used in the thesis are available on websites cited in the thesis. The stego images are generated from the image databases using source code from the website. <a href="http://dde.binghamton.edu/download/">http://dde.binghamton.edu/download/</a> Applied Computer Science
2	Digitální steganografie / Digital Steganography KOCIÁNOVÁ, Helena January 2009 (has links) Digital steganography is a technique for hiding data mostly into multimedia files (images, audio, video). With the development of information technology this technique has found its use in the field of copyright protection and secret data transfer, could be even applied in places where is limited possibility of using cryptography (e. g. by law). This thesis gives insight into digital steganography and contains an application using this technique.
3	Itérations chaotiques pour la sécurité de l'information dissimulée / Chaotic iterations for the Hidden Information Security Friot, Nicolas 05 June 2014 (has links) Les systèmes dynamiques discrets, œuvrant en itérations chaotiques ou asynchrones, se sont avérés être des outils particulièrement intéressants à utiliser en sécurité informatique, grâce à leur comportement hautement imprévisible, obtenu sous certaines conditions. Ces itérations chaotiques satisfont les propriétés de chaos topologiques et peuvent être programmées de manière efficace. Dans l’état de l’art, elles ont montré tout leur intérêt au travers de schémas de tatouage numérique. Toutefois, malgré leurs multiples avantages, ces algorithmes existants ont révélé certaines limitations. Cette thèse a pour objectif de lever ces contraintes, en proposant de nouveaux processus susceptibles de s’appliquer à la fois au domaine du tatouage numérique et au domaine de la stéganographie. Nous avons donc étudié ces nouveaux schémas sur le double plan de la sécurité dans le cadre probabiliste. L’analyse de leur biveau de sécurité respectif a permis de dresser un comparatif avec les autres processus existants comme, par exemple, l’étalement de spectre. Des tests applicatifs ont été conduits pour stéganaliser des processus proposés et pour évaluer leur robustesse. Grâce aux résultats obtenus, nous avons pu juger de la meilleure adéquation de chaque algorithme avec des domaines d’applications ciblés comme, par exemple, l’anonymisation sur Internet, la contribution au développement d’un web sémantique, ou encore une utilisation pour la protection des documents et des donnés numériques. Parallèlement à ces travaux scientifiques fondamentaux, nous avons proposé plusieurs projets de valorisation avec pour objectif la création d’une entreprise de technologies innovantes. / Discrete dynamical systems by chaotic or asynchronous iterations have proved to be highly interesting toolsin the field of computer security, thanks to their unpredictible behavior obtained under some conditions. Moreprecisely, these chaotic iterations possess the property of topological chaos and can be programmed in anefficient way. In the state of the art, they have turned out to be really interesting to use notably through digitalwatermarking schemes. However, despite their multiple advantages, these existing algorithms have revealedsome limitations. So, these PhD thesis aims at removing these constraints, proposing new processes whichcan be applied both in the field of digital watermarking and of steganography. We have studied these newschemes on two aspects: the topological security and the security based on a probabilistic approach. Theanalysis of their respective security level has allowed to achieve a comparison with the other existing processessuch as, for example, the spread spectrum. Application tests have also been conducted to steganalyse and toevaluate the robustness of the algorithms studied in this PhD thesis. Thanks to the obtained results, it has beenpossible to determine the best adequation of each processes with targeted application fields as, for example,the anonymity on the Internet, the contribution to the development of the semantic web, or their use for theprotection of digital documents. In parallel to these scientific research works, several valorization perspectiveshave been proposed, aiming at creating a company of innovative technology. Dissimulation d'informations Étalement de spectre Exposant de Lyapunov Internet Iterations chaotiques Modèles mathématiques Preuve de sécurité Protection des documents numériques Robustesse Sécurité informatique Sécurité des données Sécurité topologique Stéganalyse Stéganographie Stégo-sécurité Syqstèlesss dynamiques discrets Tatouage numérique Tests applicatifs Théorie du chaos Topologie Vie privée Application tests Chaotiques iterations; Chaos theory Computer security Data hiding Data security Digital Watermarking Discret dynamycal systems Internet Lyapunov exponent Mathematics models Privacy Protection of digital documents Robustness Security proofs Spread spectrum Steganalysis Steganography Stego-security Topological security Topology 005.8

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