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Dissertations / Theses on the topic 'Image Encryption'
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Bowley, James. "Sparse image representation with encryption." Thesis, Aston University, 2013. http://publications.aston.ac.uk/20914/.
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In this thesis we present an overview of sparse approximations of grey level images. The sparse representations are realized by classic, Matching Pursuit (MP) based, greedy selection strategies. One such technique, termed Orthogonal Matching Pursuit (OMP), is shown to be suitable for producing sparse approximations of images, if they are processed in small blocks. When the blocks are enlarged, the proposed Self Projected Matching Pursuit (SPMP) algorithm, successfully renders equivalent results to OMP. A simple coding algorithm is then proposed to store these sparse approximations. This is shown, under certain conditions, to be competitive with JPEG2000 image compression standard. An application termed image folding, which partially secures the approximated images is then proposed. This is extended to produce a self contained folded image, containing all the information required to perform image recovery. Finally a modified OMP selection technique is applied to produce sparse approximations of Red Green Blue (RGB) images. These RGB approximations are then folded with the self contained approach.
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Akdag, Sadik Bahaettin. "An Image Encryption Algorithm Robust To Post-encryption Bitrate Conversion." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607710/index.pdf.
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In this study, a new method is proposed to protect JPEG still images through encryption by employing integer-to-integer transforms and frequency domain scrambling in DCT channels. Different from existing methods in the literature, the encrypted image can be further compressed, i.e. transcoded, after the encryption. The method provides selective encryption/security level with the adjustment of its parameters. The encryption method is tested with various
images and compared with the methods in the literature in terms of scrambling performance, bandwidth expansion, key size and security. Furthermore this method is applied to the H.263 video sequences for the encryption of I-frames.
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Uehara, Takeyuki. "Contributions to image encryption and authentication." Access electronically, 2003. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20040920.124409/index.html.
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Norman, Kelly Robert. "Encryption of Computer Peripheral Devices." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1232.pdf.
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Cheng, Howard Chi Ho. "Partial encryption for image and video communication." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ34345.pdf.
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Maniccam, Suchindran S. "Image-video compression, encryption and information hiding /." Online version via UMI:, 2001.
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Manisekaran, Pradheep [Verfasser]. "Image Encryption by Using ACGLML / Pradheep Manisekaran." München : GRIN Verlag, 2021. http://d-nb.info/123663103X/34.
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Wadhwani, Sandeep. "Using chaotic encryption schemes in distributed image storage." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119757.
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Security and privacy of photos stored in the clear in third party servers has been the biggest concern for customers in recent years. One way of enhancing the privacy and security of photos stored in third party servers is to encrypt the photos before storing them. However, using encryption to secure the information held in the photos precludes applying any image processing operations while they are held in the third party servers. To address this issue, we have designed and implemented a distributed image storage system that is based on the Chord protocol which enhances privacy using chaotic map transformations and image segmentation. The distributed system we use has two types of resources: trusted server resources and untrusted peer-to-peer resources. The images are encrypted using an Arnold's cat map algorithm and split into strips before uploaded to the destination machines. The cat map algorithm shuffles an image pixels and produces a noise-like image. A pixelated (a group of nearby pixels are made the same color) image of the original image is generated to represent it in the central server. From the pixelated image we generate the key parameters that control the cat map transformations. A variety of pixel-level, block-level and binary filters have been implemented to support image processing on encrypted images in the system. One of the concerns of using cat maps for security purposes is the quality of shuffling provided by these transformations. For certain parameter values and image sizes cat map transformations reveal the original image as ghosts or clusters. As part of my thesis, I studied the ghost and cluster formation scenarios. I performed many experiments and proposed simple tests that can be used to detect the parameter values that should be avoided.La sécurité et l'intimité des images électronique stockée dans des serveurs tierces est une des plus grandes préoccupations de nos jours. L'une des manières d'améliorée la sécurité est de crypter les données contenu dans les images avant de les télécharger vers le serveur en question. Cependant, le fait d'utiliser des techniques cryptographiques pour assurer la sécurité des images, ce la empêche l'application d'opérations de traitement d'images pendant qu'ils résident sur les serveurs. Pour résoudre ce problème, nous avons conçu et mis en œuvre un système distribué pour télécharger les images sur les serveurs qui est basée sur le protocole "Chord", améliorant la sécurité en utilisant des techniques de la théorie du chaos pour transformer l'image puis finalement la segmenter. Le système distribué que nous utilisons contient deux types de ressources : des ressources de serveur fiable et des ressources non fiables paires à pair. Les images sont cryptées avec l'application de l'algorithme chat d'Arnold, l'image résultante est divisée en morceaux avant d'être télécharger aux machines destinataires. L'algorithme de chat d'Arnold produit une image bruyante. Une image pixélisé (un groupe de pixels voisines sont changer de façon que les couleurs soient les même entre eux) est aussi créé de l'image originale. L'image pixélisée est utilisé pour représenter l'image originale sur le serveur central. A partir de l'image pixélisée, nous créerons les paramètres de la clé qui contrôlent la transformation chaotique. Une variété de filtres au niveau des pixels, blocs des pixels et de la représentation binaire ont été mis en œuvre pour permettre des opérations de traitement sur les images cryptées dans le système. La qualité du brouillement en utilisant les transformations chaotiques est un souci par rapport à la sécurité. Pour certaines valeurs de paramètres et dimensions d'images, on peut percevoir des fantômes de l'image originale. Pour ma thèse de maitrise, J'ai étudié les scenarios qui donnent naissance à des formations de fantômes. J'ai effectué de nombreuses méthodes expérimentales et proposer des simples testes pour pouvoir détecter les valeurs de paramètres qui doivent être évité.
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Basavarasu, Srinivasa R. "Voice and Image Encryption, and, Performance Analysis of Counter Mode Advanced Encryption Standard for WiMAX." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1376636620.
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Wu, Pianhui. "Research on digital image watermark encryption based on hyperchaos." Thesis, University of Derby, 2013. http://hdl.handle.net/10545/305004.
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The digital watermarking technique embeds meaningful information into one or more watermark images hidden in one image, in which it is known as a secret carrier. It is difficult for a hacker to extract or remove any hidden watermark from an image, and especially to crack so called digital watermark. The combination of digital watermarking technique and traditional image encryption technique is able to greatly improve anti-hacking capability, which suggests it is a good method for keeping the integrity of the original image. The research works contained in this thesis include: (1)A literature review the hyperchaotic watermarking technique is relatively more advantageous, and becomes the main subject in this programme. (2)The theoretical foundation of watermarking technologies, including the human visual system (HVS), the colour space transform, discrete wavelet transform (DWT), the main watermark embedding algorithms, and the mainstream methods for improving watermark robustness and for evaluating watermark embedding performance. (3) The devised hyperchaotic scrambling technique it has been applied to colour image watermark that helps to improve the image encryption and anti-cracking capabilities. The experiments in this research prove the robustness and some other advantages of the invented technique. This thesis focuses on combining the chaotic scrambling and wavelet watermark embedding to achieve a hyperchaotic digital watermark to encrypt digital products, with the human visual system (HVS) and other factors taken into account. This research is of significant importance and has industrial application value.
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Chen, Hang. "Optical Encryption Techniques for Color Image and Hyperspectral Data." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0374.
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La sécurité est un problème important dans la transmission et le stockage de l'image, tandis que le cryptage est un moyen d'assurer la sécurité qui est requise dans de nombreuses applications (télévision par câble, la communication d'images militaires, systèmes d'imagerie confidentielle, etc.). Toutefois, à l'instar du message texte, les données images présentent des caractéristiques spéciales telles que la haute capacité, la redondance et la haute corrélation entre les pixels, et nécessite souvent une transmission et des traitements temps réel pour certaines applications. Construire un système rapide et efficace de cryptographie d'images suscite un intérêt considérable. C'est dans ce contexte qu’ont été menés ces travaux thèse qui portent sur l’élaboration d’un corrélateur optique en termes de cryptage/décryptage des données pour son implémentation dans un montage optique innovant. L’objectif de ces travaux est de réaliser un système optique de chiffrement sur la base d'exploitation de transformation optique et de générateurs chaotiques. L'idée originale des travaux consiste à exploiter la non-linéarité des systèmes chaotiques comme clés de chiffrement pour les systèmes optiques de chiffrement d'images multispectrales. Dans ces travaux de thèse, nous avons proposés et évalués plusieurs chiffrements d'images à base d’un système hyperchaotique et de transformées optiques (gyrator, Fourier, Baker , Arnold et Gerchberg- Saxton) à partir d’un processus de cryptage reposant sur une décomposition composants RVB et un encodage dans un flux dimensionnel d’images couleurs. L'originalité des solutions de chiffrement adoptée reposent sur l'exploitation de signaux réellement aléatoires à travers la mise en œuvre de générateurs hyperchaotiques pour la génération de données aléatoires sous forme images comme base de matrices de clés de chiffrement. En effet, ces générateurs présentent des propriétés et des caractéristiques fondamentales en termes de cryptage car il présente une non-linéarité, une imprédictibilité et une extrême sensibilité aux conditions initiales les rendant très intéressantes pour le développement de clés de chiffrement par flot. L’algorithme mis en œuvre permet d'extraire en temps réel les caractéristiques de texture dans les différentes bandes spectrales d'images en vue d’évaluer et de détecter les teneurs potentielles en information et dont les transmissions doivent être sécurisée via une transmission optiqueOptical information security is one of the most important research directions in information science and technology, especially in the field of copyright protection, confidential information transmission/storage and military remote sensing. Since double random phase encoding technology (DRPE) was proposed, optical image encryption technology has become the main topic of optical information security and it has been developed and studied deeply. Optical encryption techniques offer the possibility of high-speed parallel processing of two dimension image data and hiding information in many different dimensions. In this context, much significant research and investigation on optical image encryption have been presented based on DRPE or further optical operation, such as digital holography, Fresnel transform, gyrator transform. Simultaneously, the encrypted image has been extended from single gray image to double image, color image and multi-image. However, the hyperspectral image, as a significant element in military and commercial remote sensing, has not been deeply researched in optical encryption area until now. This work extends the optical encryption technology from color image to hyperspectral image. For better comprehension of hyperspectral image encryption, this work begins with the introduction and analysis of the characteristics of hyperspectral cube. Subsequently, several kinds of encryption schemes for color image, including symmetric and asymmetric cryptosystem, are presented individually. Furthermore, the optical encryption algorithms for hyperspectral cube are designed for securing both the spatial and spectral information simultaneously. Some numerical simulations are given to validate the performance of the proposed encryption schemes. The corresponding attack experiment results demonstrate the capability and robustness of the approaches designed in this work. The research in this dissertation provides reference for the further practicality of hyperspectral image encryption
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Ullagaddi, Vishwanath. "Development of Data Encryption Algorithms for Secure Communication Using Public Images." University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1341524458.
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Wang, Mengmeng. "Optical Image encryption based on apertured FrMT in the Diffraction domain." Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2326.
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Cette thèse se concentre sur l'étude de l'introduction de l'ouverture dans la transformation frationnelle de Mellin (TFrM) dans le domaine de diffraction et son application dans le système de cryptage d'images optiques. La faisabilité des schémas de cryptage proposés est vérifiée par une série de simulations numériques. Les travaux principaux sont les suivants:Tout d'abord, un système de cryptage d'images optiques basé sur la transformation fractionnelle de Mellin avec une ouverture dure (TFrM à ouverture dure) a été proposé. La TFrM à ouverture dure peut être effectuée par la transformation log-polar et la transformation fractionnelle de Fourier à ouverture dans le domaine de diffraction. Les longueurs latérales de l'ouverture dure servent de clé pour améliorer la sécurité et augmenter encore l'espace clé du système de cryptage. Cette ouverture dure n'est pas seulement utilisée pour contrôler la quantité de lumière passant la lentille en ajustant sa taille, mais réduit également la fuite de lumière, ce qui, dans une certaine mesure, améliorera la robustesse contre les attaques directes.Deuxièmement, l'ouverture gaussienne, comme une ouverture douce pour équilibrer entre l'ouverture dure et aucune ouverture, est introduite dans la TFrM à ouverture. Avec la TFrM à ouverture gaussienne dans le domaine de diffraction, une transformation de préservation de la réalité est proposée et utilisée pour cryptage d'images. Dans ce schéma de cryptage pour l'image en niveaux de gris, la transformation d’Arnold et l'opération d’XOR bitwise sont également adoptées pour cypter l'image afin d'améliorer la sécurité.Enfin, l'algorithme de cryptage basé sur la TFrM à ouverture gaussian et de préservation de la réalité (TFrMOGPR) utilisé pour l'image couleur est proposé. Outre TFrMOGPR non linéaire, rotation de l'espace couleur, avec brouillage 3D et XOR opération bitwise rend l'algorithme de cryptage d'image de couleur proposé bien performer.Les résultats de la simulation ont montré que les systèmes de cryptage proposés sont capables de résister à différentes attaques communes et robustes contre les attaques de bruit et d'occlusionThis thesis focuses on the study of introducing the aperture into FrMT in diffraction domain (FrMT) and its application in optical image encryption system. The feasibility of the proposed encryption schemes is verified by a series of numerical simulations. The main work is as follows:Firstly, an optical image encryption scheme based on the fractional Mellin transform with a hard aperture has been proposed. The apertured fractional Mellin transform (apertured FrMT) can be performed through the log-polar transform and the apertured fractional Fourier transform in diffraction domain. The side-lengths of the hard aperture serve as a key to improve the security and further increase the key space of the encryption system. This hard aperture is not only used to control the amount of light passing the lens by adjusting its size, but also reduces the leakage of light, which will, to some extent, enhance the robustness against direct attacks.Secondly, the Gaussian aperture, as a soft aperture for balancing between hard aperture and no aperture, is introduced into the apertured FrMT. With the Gaussian apertured FrMT in diffraction domain, a reality-preserving transform is proposed and used for image encryption. In this encryption scheme, for gray image, the Arnold transform and the bitwise XOR operation are also adopted to encrypt the image in order to enhance the security.Finally, the encryption algorithm based on Gaussian apertured reality-preserving FrMT (GARPFrMT) used for color image is proposed. Besides, nonlinear GARPFrMT, color space rotation, together with 3D scrambling and bitwise XOR operation make the proposed color image encryption algorithm have good performance.The simulation results have shown that the proposed encryption schemes are capable of resisting different common attacks and robust against noise and occlusion attacks
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Li, Ling Feng. "An image encryption system based on two-dimensional quantum random walks." Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3950660.
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Orgill, Gregory Leavitt. "Java Performance of the Rijndael Encryption Algorithm Across Compilers and Virtual Machines." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd681.pdf.
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Wong, Hon Wah. "Image watermarking and data hiding techniques /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202003%20WONGH.
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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003.Includes bibliographical references (leaves 163-178). Also available in electronic version. Access restricted to campus users.
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Roth, Christopher. "A distributed password scheme for network operating systems." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FRoth.pdf.
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Salles, Ernesto J. "The impact on quality of service when using security-enabling filters to provide for the security of run-time extensible virtual environments." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FSalles.pdf.
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Thesis (M.S. in Modeling, Virtual Environments and Simulation)--Naval Postgraduate School, September 2002.Thesis advisor(s): J. Bret Michael, Michael Capps, Don McGregor. Includes bibliographical references (p. 123-127). Also available online.
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Chan, Fuk Wing Thomas. "Preserving trust across multiple sessions in open systems /." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd497.pdf.
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Smith, Bryan. "Responding to policies at runtime in TrustBuilder /." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd414.pdf.
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Kundur, Abhinay. "Digital and Analog Signal Encryption and Decryption in Mid RF Range Using Hybrid Acousto-Optic Chaos." University of Dayton / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1336100009.
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Haider, Rizwan. "Modified and Efficient Image Encryption Algorithm Based on Chaos Theory, DNA Complementary Rules and SHA-256." Thesis, Mittuniversitetet, Avdelningen för informations- och kommunikationssystem, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-29916.
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The emerging topic, symmetric encryption technique for digital imagesusing chaotic function and DNA bases has recently drawn a lot ofattentions from the research community. The use of voice and visualmaterial as an addition to textual data has become more widespread.Multimedia content, the core of which is the digital image, has becomean earth-shaking element in prospective information transmission. Thismeans that multimedia contents such as audio, video and images haveto be transmitted over communication channels securely using newencryption techniques.Chaos theory is a widely studied topic in non-linear dynamics becauseof features like periodicity, sensitivity to initial conditions and controlparameters. The lower dimensional discrete chaotic functions are simpleand efficient to generate a pseudo-random sequence for encryption.However, DNA cryptography is an additional weapon in thecryptographer’s armoury. Characteristics such as of vast parallelism andlarge storage capacity make it a very promising field. The algorithmsbased on DNA and discrete chaotic functions use the advantages of bothfields to provide image protection in an effective way.Traditional digital cryptosystems like DES, AES and RSA are designedprimarily for textual data, which does not fit the multimedia streambecause of the essential structures of image data such as large size, solidpixel correlation and high redundancy, which incurs significantoverhead. Also, in conventional cryptographic techniques, thedecrypted data is exactly the same as plaintext data.To solve this problem, symmetric encryption aims to provide sufficientsecurity with an important gain in computational complexity anddelays, thereby making the cipher suitable for real time applications.This study uses an encryption approach by adding adjacent rows andcolumns of plain text after converting into DNA bases in order to reducethe encryption overhead. To improve the use of DNA complementary rules in a better and moredynamic way, and to incorporate DNA diffusion prior to the encryptionalgorithm, a complete set of DNA complementary rules is employed inthe encryption and decryption process. The selection of DNA rules foreach block is made depending on the chaotic sequence. The initialconditions and control parameters of the chaotic maps are madedepending on the 256-bits hash value which is generated from a plainimage to avoid chosen plaintext attacks.
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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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Yip, Shu Kei. "Digital watermarking and data hiding /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?ECED%202006%20YIP.
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Li, Richard Yuk Ming. "Digital watermarking and data hiding /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?ECED%202007%20LIR.
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Zhang, Bo. "XOR based optical encryption with noise performance modeling and application to image transmission over wireless IP lan." Thesis, Peninsula Technikon, 2004. http://hdl.handle.net/20.500.11838/1376.
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Thesis (MTech (Information Technology))--Peninsula Technikon, 2004Encryption was used whenever someone wanted to send a secret message to someone. The quality of the algorithm and key combination were the factors that ensured the strength of the system. However, until there were some automation one could not use complex methods for encryption because it simply took too long to encrypt and decrypt messages (even worse for images), manually. Optical technologies have recently been employed in encryption. Compared with traditional computer and electrical systems, optical technologies offer primarily two types of benefits, namely optical systems have an inherent capability for parallel processing, that is, rapid transmission of information, and information can be hidden in any of several dimensions, such as phase or spatial frequency. Optical systems therefore have an excellent capability for encoding information. In this project an image encryption technique was developed using exclusive-OR (XOR) operations in the optical domain before the captured image entered a digital computer network for further processing. A gray-level image of the object to be encrypted was converted a binary format and a pixel by pixel exclusive OR operation was performed on it with a random key-bit by making use of polarization encoding in LCD technology, before the encrypted binary image was detected by a CCD. The image may also be used as an input to a computer for comparison with a database. However, noise alters the encrypted bit and the value of the noisy encrypted bit is no longer binary. In this research the encryption techniques was evaluated and tested for applicability to encrypt and decrypt successfully. The noise performance was tested and compared. The technique was applied for image transmission over a wireless IP broadband link. Images (optical and thermal) captured from telemedicine application was transmitted and decrypted with reasonable success in this application.
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Fu, Ming Sun. "Data hiding watermarking for halftone images /." View abstract or full-text, 2003. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202003%20FU.
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Leung, Wing Pan. "Visual cryptography for color images : formal security analysis and new construction /." access full-text access abstract and table of contents, 2009. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?mphil-cs-b23759100f.pdf.
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Thesis (M.Phil.)--City University of Hong Kong, 2009."Submitted to Department of Computer Science in partial fulfillment of the requirements for the degree of Master of Philosophy." Includes bibliographical references (leaves 103-108)
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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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Chaparala, Suman Krishna. "Secure Encryption and Decryption by Aperture Variations of a Photodetector in an Acousto-Optic Bragg Cell." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1468527741.
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Woo, Tim. "A Scalable, Secure, and Energy-Efficient Image Representation for Wireless Systems." Thesis, University of Waterloo, 2004. http://hdl.handle.net/10012/940.
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The recent growth in wireless communications presents a new challenge to multimedia communications. Digital image transmission is a very common form of multimedia communication. Due to limited bandwidth and broadcast nature of the wireless medium, it is necessary to compress and encrypt images before they are sent. On the other hand, it is important to efficiently utilize the limited energy in wireless devices. In a wireless device, two major sources of energy consumption are energy used for computation and energy used for transmission. Computation energy can be reduced by minimizing the time spent on compression and encryption. Transmission energy can be reduced by sending a smaller image file that is obtained by compressing the original highest quality image. Image quality is often sacrificed in the compression process. Therefore, users should have the flexibility to control the image quality to determine whether such a tradeoff is acceptable. It is also desirable for users to have control over image quality in different areas of the image so that less important areas can be compressed more, while retaining the details in important areas. To reduce computations for encryption, a partial encryption scheme can be employed to encrypt only the critical parts of an image file, without sacrificing security. This thesis proposes a scalable and secure image representation scheme that allows users to select different image quality and security levels. The binary space partitioning (BSP) tree presentation is selected because this representation allows convenient compression and scalable encryption. The Advanced Encryption Standard (AES) is chosen as the encryption algorithm because it is fast and secure. Our experimental result shows that our new tree construction method and our pruning formula reduces execution time, hence computation energy, by about 90%. Our image quality prediction model accurately predicts image quality to within 2-3dB of the actual image PSNR.
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Kailasanathan, Chandrapal. "Securing digital images." Access electronically, 2003. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20041026.150935/index.html.
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Noura, Mohamad. "Solutions cryptographiques efficaces et sécurisées pour les données médicales." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCD037.
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Dans cette thèse, des schémas cryptographiques efficaces et robustes ont été proposés pour surmonter les problèmes actuels de sécurité et de confidentialité des systèmes et applications médicaux récents. La principale contribution de cette thèse est d'atteindre un haut niveau de sécurité avec un minimum de surcoût de calcul contrairement à de nombreuses autres solutions existantes. Par conséquent, deux schémas de chiffrement et une approche de disponibilité des données ont été proposés pour les données médicales afin de garantir les services de sécurité suivants : confidentialité, intégrité et disponibilité des données ainsi que l'authentification de la source. Les solutions cryptographiques proposées sont basées sur les structures de chiffrement cryptographiques dynamiques pour assurer une meilleure résistance aux attaques existantes et modernes. De plus, ces solutions ont été conçues pour être légères et ne nécessitent qu'un petit nombre d'itérations. La fonction de chiffrement proposée n'est répétée qu'une seule fois et utilise une permutation de bloc dépendante de la clé.Elle satisfait également les propriétés de confusion et de diffusion requises, assurant ainsi les propriétés cryptographiques souhaitables. Les résultats de simulation et d'expérimentation ont démontré l'efficacité et la robustesse des solutions cryptographiques proposées. De plus, l'utilisation des schémas cryptographiques proposés ouvre la porte à des algorithmes cryptographiques dynamiques qui peuvent conduire à un gain de performance et de sécurité significatif par rapport à l'état de l'artIn this thesis, effective and robust cryptographic schemes were proposed to overcome the current security and privacy issues of recent medical systems and applications. The main contribution of this thesis is to reach a high level of security with minimum possible overhead contrary to many other existing solutions. Therefore, two cipher schemes and a data availability approach were proposed for medical data to ensure the following security services: data confidentiality, integrity and availability as well as source authentication. The proposed cryptographic solutions are based on the dynamic cryptographic cipher structures to ensure a better resistance against existing and modern attacks. Moreover, these solutions were designed to be lightweight and they require a small number of iterations. The proposed ciphers round function is iterated only once and uses a key dependent block permutation. It also satisfies the required confusion and diffusion properties, consequently ensuring the desirable cryptographic properties. Simulation and experimental results demonstrated the efficiency and the robustness of the proposed cryptographic solutions. Furthermore, employing the proposed cryptographic schemes open the door to a dynamic cryptographic algorithms that can lead to a significant performance and security gain compared with other recent related state-of-art
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Mohamed, Ali. "Investigation of Anisoplanatic Chaos-based Signal and Image Transmission and Retrieval Through Atmospheric Phase Turbulence." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1583406088398142.
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He, Kun. "Content privacy and access control in image-sharing platforms." Thesis, CentraleSupélec, 2017. http://www.theses.fr/2017CSUP0007.
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Au cours de ces dernières années, de plus en plus d’utilisateurs choisissent de diffuser leurs photos sur des plateformes de partage d’images. Ces plateformes permettent aux utilisateurs de restreindre l’accès aux images à un groupe de personnes, afin de donner un sentiment de confiance aux utilisateurs vis-à-vis de la confidentialité de ces images. Malheureusement, la confidentialité ne peut être garantie sachant que le fournisseur de la plateforme a accès aux contenus de n’importe quelle image publiée sur sa plateforme. En revanche, si les images sont mises en ligne chiffrées, seules les personnes ayant la possibilité de déchiffrer les images, auront accès aux images. Ainsi, la confidentialité peut être assurée. Trois principales spécificités sont à prendre en compte lors du chiffrement d’une image : le schéma de chiffrement doit être effectué en respectant le format de l’image (e.g. format JPEG), garantir l’indistinguabilité (l’adversaire ne doit obtenir de l’information sur le contenu de l’image à partir de l’image chiffrée), et doit être compatible avec les traitements des images spécifiques à la plateforme de partage d’images. L’objectif principal de cette thèse a été de proposer un tel schéma de chiffrement pour les images JPEG. Nous avons d’abord proposé et implémenté un schéma de chiffrement garantissant la conservation de l’image et l’indistinguabilité. Malheureusement, nous avons montré que sur Facebook, Instagram, Weibo et Wechat, notre solution ne permettait de maintenir une qualité d’images suffisante après déchiffrement. Par conséquent, des codes correcteurs ont été ajoutés à notre schéma de chiffrement, afin de maintenir la qualité des imagesIn recent years, more and more users prefer to share their photos through image-sharing platforms. Most of platforms allow users to specify who can access to the images, it may result a feeling of safety and privacy. However, the privacy is not guaranteed, since at least the provider of platforms can clearly know the contents of any published images. According to some existing researches, encrypting images before publishing them, and only the authorised users who can decrypt the encrypted image. In this way, user’s privacy can be protected.There are three challenges when proposing an encryption algorithm for the images published on image-sharing platforms: the algorithm has to preserve image format (e.g. JPEG image) after encryption, the algorithm should be secure (i.e. the adversary cannot get any information of plaintext image from the encrypted image), and the algorithm has to be compatible with basic image processing in each platform. In this thesis, our main goal is to propose an encryption algorithm to protect JPEG image privacy on different image-sharing platforms and overcome the three challenges. We first propose an encryption algorithm which can meet the requirements of the first two points. We then implement this algorithm on several widely-used image-sharing platforms. However, the results show that it cannot recover the plaintext image with a high quality after downloading the image from Facebook, Instagram, Weibo and Wechat. Therefore, we add the correcting mechanism to improve this algorithm, which reduces the losses of image information during uploading the encrypted image on each platform and reconstruct the downloaded images with a high quality
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Suresh, V. "Image Structures For Steganalysis And Encryption." Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/2273.
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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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Yen, Jun-Zhong, and 顏君仲. "Online/Offline Image Encryption Mechanism." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/47224732554143659596.
Full textAbstract:
碩士國立臺灣海洋大學
資訊工程學系
101
In this paper, an online/offline image encryption scheme based on chaotic system to provide a high speed image encryption is proposed. Our scheme uses index value of chaotic system to rearrange for position of image pixel and accommodates the concept of online/offline to decrease the time of image encryption. The value of index and chaotic sequence are calculated before getting image that we called the offline stage. In the online stage, image encryption can be quickly carried out. Experiment results show that our proposed scheme outperforms previously proposed one.
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Hsiao, Hung-Yi, and 蕭弘益. "A Study of Chaotic Image Encryption." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/r7p54c.
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碩士中原大學
電機工程研究所
93
In this thesis, the chaotic image encryption is studied by using properties of chaos including deterministic dynamics, unpredictable behavior and non-linear transform. By these chaotic properties, the positions and values of the pixels of original image are randomly rearranged with the user key. As a result, the cipher image is able to reach a good properties of diffusion and confusion. Our proposed new scheme of chaotic image encryption can be briefly described as follows. At first, we utilize the one-dimensional logistic map to generate the encryption key, scrambling image table and noise image. Then, the source image (i.e., plaintext) is scrambled with scrambling image table and performed exclusive OR operation with the encryption key. Furthermore, several transformed images according above procedures are embedded into a noise image by watermarking techniques to form a pre-encryption image. Finally, scrambling processes and exclusive OR operations with key length of 256, 512 and 1024 bits are executed to obtain the encryption image. Our contribution of the proposed new chaotic image encryption scheme is that, by MATLAB simulation, the cipher images have 6 good characteristics as follows. (1)The correlation between source image and cipher image is very small, almost equal to zero. That is, the source image and cipher image are mostly independent. In addition, the correlation among the cipher images is almost zero. This represents the cipher images are mostly independent, too. (2)The histogram of cipher image pixels is uniform nearly. Namely, our cipher image holds a good confusion property on the statistics. (3)From the simulation of the two-dimensional discrete Fourier transform and shift zero-frequency component of discrete Fourier transform to center of spectrum, we can discovery the energy at the spectrum is consistent, i.e., our cipher image possesses good diffusion property on the statistics. (4)The size of the noise image is able to be adjusted (the size of noise image must equal to or bigger than the size of source image) to protect the source image (plain image). Via the noise image, it lets us to get excellent confusion and diffusion properties of cipher images according to the MATLAB simulations. That is to say, our encryption method derives a good security on communication. (5)Our encryption algorithm is easy to implement on the IC chip. (6)The encryption performance is nice. To sum up, for our proposed new scheme of the chaotic image encryption, the noise image plays a important role. The cipher image characteristic of statistics on confusion and diffusion become excellent due to join the noise image. That is, our new chaotic image encryption method can acquire very fine ciphertext and communication safety.
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Wu, Chang-Sian, and 巫昌憲. "A Study of Batch Image Encryption." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/93711550800291119496.
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碩士國立嘉義大學
資訊工程學系研究所
95
As the network bandwidth has gained much more growth, it’s nowadays popular to share a large number of still images via the Internet by means batch transmission. This trend carries out people’s desire for enjoying online multimedia services. In order to keep the confidentiality of traveling images, traditional encryption techniques seem to be well designed to meet this requirement. However, it’s well-known that the size of image is generally much larger than that of text. Furthermore, partial distortion of images is allowed by human visual systems. Hence, traditional cryptographic encryption algorithms are sometimes not suitable for being used directly to encrypt a batch of images. On the other hand, most of the existing schemes aimed at encrypting a single image so that the schemes can potentially be improved to encrypt a batch of images at once in an efficient way. In this thesis, four novel batch image encryption algorithms based on either Visual Cryptography (VC) or Vector Quantization (VQ) are presented to benefit from their computational efficiency and low transmission bandwidth without damaging the original compression rate. The experimental results show the performance in terms of compression rate and extra encryption computational cost.
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Ou-Yang, Yen, and 歐陽諺. "Fast Image Encryption Based on Lifting Wavelet Transform and Advanced Encryption Standard." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/89200471963606880129.
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碩士大葉大學
資訊工程學系碩士班
99
In this thesis, We simulate wavelet hierarchical features, combined with the the look-up table of Advanced Encryption Standard, and the mix column’s finite fields GF(28) multiplication and addition, and propose a low-volume image encryption algorithm, which considers digital image as a big block and encryption of the big block. The selection and generation of subkey depends on the user’s key, make the encryption, decryption and key generation system use the same algorithm. The results (effects) of encryption and decryption can be achieved by only changing look-up table for encryption and decryption. The simulation results show the proposal can effectively resists various attacks when the encryption rounds are at least more than two rounds (ex. statistical analysis, differential attack ....). Our proposal uses the hierarchical concept of wavelet transformation as the concept of the rapid diffusion and confusion, with great avalanche effect.
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劉江龍. "An Image Encryption Schme with Compression Effect." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/28801436180557353851.
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碩士國防管理學院
資源管理研究所
83
A private key encryption scheme for a two-dimensional image data is proposed in this work. This scheme is designed on the basis of lossless data compression principle. The proposed scheme is developed to have both data encryption and compression performed simultaneously. For the lossless data compression effect, the quadtree data structure is used to represent the image; for the encryption purpose, various scanning sequences of image data are provided. The scanning sequences comprise of a private key for encryption. 24 possible combinations of scanning sequences are defined for accessing four quadrants, thereby making available 24n×4n(n-1)/2 possibilities to encode an image of resolution 2n×2n, The security of the proposed encryption scheme therefore relies on the computational infeasibility of an exhaustive search approach. Also, a differential quadtree encryption scheme for gray-level and color image is proposed to enhence the compression effect. Ten images of 512×512 pixels are used to verify the feasibility of the proposed scheme. Two of them are binary image. Five of them are gray images. and the rest three are color images. The results of testing and analysis demonstrate the characteristics of the proposed scheme. This scheme can be applied for problems of data storage or transmission in a public network.
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Hsu, Y. H., and 許怡樺. "Image Hybrid Encryption Based on Chaotic Systems." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/92878874310440753110.
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碩士國立彰化師範大學
工業教育與技術學系
99
Since the dynamic trajectory of chaos system has the high sensitivity to the initial value and the variation of parameter, the application of chaos system to encryption of images can improve the security of image transmission. This thesis proposes a chaos system based hybrid color-image technique with Arnold Cat Map (ACM), Baker Map (BM) and Line Map (LM). The proposed system can completely scatter the outline of images and disarray the distribution feature of color levels. Besides, it has an extreme key space. Eventually, an encryption software program which can demonstrates the dynamic trajectory of chaos system, the effect of encryption of images, and some statistic data of security is developed in the study. Security tests of the program include information entropy, relation coefficient, MSE, NPCR, and UACI. The experimental results prove the high effect and encryption security of the proposed technique. Keyword: Chaos System, Image encryption, Bit-Chaotic-Shuffle, Statistic data of security, Hybrid encryption.
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Hsu, Po-Yu, and 許柏昱. "Secret Sharing with Image Encryption Access Control Mechanisms for Digital Images." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/dk5e2e.
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碩士亞洲大學
資訊多媒體應用學系
103
Privacy is the import issue in recent years. To protect the image privacy, access control is the general way to authorize different groups with different abilities to see authorized contents. Visual cryptography is a technique to encode the secret image into several meaningless shares; Later, the secret image can be reconstructed by stacking shares without any computations. In visual cryptography, three main problems are discussed: pixel expansion, contrast and share management. Pixel expansion is the problem that the reconstructed image is bigger than the original one. Contrast is a measure to judge whether the reconstructed image is easy to recognize. Share management is the problem for administrator on difficult to manage and dispatch the shares to participants because the contents of shares are meaningless. The other techniques are image encryption and image authentication. Image encryption helps owners encrypt the image to prevent from secret leakage. Image authentication is used to authenticate whether the image is not a fake one. In this paper, two methods are provided. First, based on visual cryptography, a hybrid secret sharing with access control is proposed. The tag image is hidden into the shares. Next, the tag images can be obtained by self-stacking the shares for administrator to resolve the share management problem. Also, the experiments show no pixel expansion problem. The second method encrypts the whole or parts of secret image according to the authorization. The authentication codes are embedded back to the encrypted image. The authentication codes are extracted to judge whether the decrypted image is authentic. The experiments prove its feasibility and effective.
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Yu-Chia, Liu, and 劉育嘉. "Acceleration of the Encryption of Digital Medical Image." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/59589941446042049381.
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碩士台北醫學院
醫學資訊研究所
89
The hospital digitalization makes all doctors got more quick and efficient work. Digital image transits for end to end to doctors for diagnosis or other purpose at 1’st step, this need time control. So big as digital image data for transits is already wasting time, now we need to maintain security issue too, so it waste more time to have security procedure as encryption, water marking, digital signature… At our encryption, we have use all now a day encryption techniques and make use of unimodular mathematical algorithm for our architecture of digital image data. Now, we announce new algorithm for faster encryption to only digital images and should makes doctors have their information at most first time.
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Chuang, Ming-Chuan, and 莊銘權. "Suitable for JPEG 2000 Image Encryption/Decryption Scheme." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/85047454584863342890.
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碩士國防大學中正理工學院
電子工程研究所
96
Image encryption is a very important part for image security. Image compression technologies change with each passing day. They not only improve compression efficiency, but also provide a rich set of features for a variety of applications. Therefore, an efficient image encryption method should be developed according to the characteristics of the compression technique itself. JPEG 2000 is an emerging standard for still image compression. JPEG 2000 provides various functionalities to solve the problems for different image applications and possibly become a most popular image format. Therefore, JPEG 2000 image encryption has become a hot topic for image security. One of the important properties of JPEG 2000 codestream is that the two consecutive bytes in the packet body should be in the interval [0x0000, 0xFF8F] so that a standard JPEG 2000 decoder can exactly decode the JPEG 2000 compressed codestream. This is so called the compatibility of JPEG 2000 and should be followed by an effective JPEG 2000 encryption method. This thesis proposes a cryptography-based JPEG 2000 image encryption technique which uses the stream cipher to encrypt the JPEG 2000 codestream. To be compatible with the syntax of JPEG 2000, the proposed technique replaces the syntax non-compliant bytes with syntax compliant bytes and records the positions of these bytes as the deciphering information. The deciphering information is then embedded in the header of the JPEG 2000 codestream making use of the characteristics of the syntax of the JPEG 2000 to facilitate the decryption in the decoding side. Experimental results show that the proposed JPEG 2000 image encryption scheme not only can be compliant with the syntax of JPEG 2000, but also can encrypt the entire packets of the JPEG 2000 codestream. That is, the proposed technique has good compatibility and security. Moreover, because the extra deciphering information generated in the encryption process is very small, the proposed technique is also compression equivalent. According to the good properties mentioned above, the proposed JPEG 2000 image encryption technique can provide effective protection of JPEG 2000 images in various applications.
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Barakat, Mohamed L. "Hardware Realization of Chaos Based Symmetric Image Encryption." Thesis, 2012. http://hdl.handle.net/10754/234953.
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This thesis presents a novel work on hardware realization of symmetric image encryption utilizing chaos based continuous systems as pseudo random number generators. Digital implementation of chaotic systems results in serious degradations in the dynamics of the system. Such defects are illuminated through a new technique of generalized post proceeding with very low hardware cost. The thesis further discusses two encryption algorithms designed and implemented as a block cipher and a stream cipher. The security of both systems is thoroughly analyzed and the performance is compared with other reported systems showing a superior results. Both systems are realized on Xilinx Vetrix-4 FPGA with a hardware and throughput performance surpassing known encryption systems.
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Wang, Chin-Yuan, and 王群元. "FPGA Implementation of Chaos Algorithm for Image Encryption." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/14013934425841318521.
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碩士國立成功大學
工程科學系碩博士班
95
A FPGA-based image capture system with chaotic encryption is developed in this thesis. The immediate image is captured via the COMS sensor, and then encrypted and decrypted by FPGA module. The Logistic map is employed as the encryption algorithm, which designed by the IEEE 754 floating point module to improve the accuracy of the result. For testing the feasibility of this system, the solutions of encryption and decryption are presented and valided on PC. It has been shown that this system can work effectively for image encryption and decryption operations.
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Yekkala, Anil Kumar. "Analysis And Design Of Image And Video Encryption Algorithms." Thesis, 2006. http://hdl.handle.net/2005/436.
Full textAbstract:
The rapid growth in multimedia based Internet systems and applications like
video telephony, video on demand, network based DVD recorders and IP
television has created a substantial need for multimedia security. One of the important requirements for multimedia security is transmission of the digital multimedia content in a secure manner using encryption for protecting it from eavesdropping. The simplest way of encrypting multimedia content is to consider the two-dimensional/three-dimensional image/video stream as an one-dimensional stream and to encrypt the entire content using standard block ciphers like AES, DES, IDEA or RC4 or using a stream cipher. The method of encrypting the entire multimedia content is considered as a naive encryption approach. Even though the naive encryption approach provides the desired security requirements, it imposes a large overhead on the multimedia codex. This is due to the size of the multimedia content, and also due to real time requirements of transmission and rendering. Hence, lightweight encryption schemes are gaining popularity for multimedia encryption. Lightweight Encryption schemes are based on the principle “Encrypt minimal and induce maximum noise". Lightweight encryption schemes are designed to take the structure of the multimedia content into consideration.
In our work we analyze some of the existing lightweight encryption schemes for digital images and video. The analysis is done based on the amount of security, scalability and effect on compression. A detailed study of some of the existing
lightweight encryption schemes is also done by designing cryptanalysis
schemes. The cryptanalysis schemes are designed using image noise clearing
algorithms and pixel prediction techniques. The designed cryptanalysis schemes reduce the amount of noise introduced by the corresponding lightweight encryption schemes considerably. Based on our analysis of existing lightweight
encryption schemes, we propose a set of more robust lightweight encryption
schemes for images and video. The proposed lightweight encryption schemes
are secure, scalable, and do not degrade the compression achieved. In our work, we also propose a few enhancements to JPEG image compression for achieving more compression, without compromising on the quality. The enhancements to the JPEG compression are extensions of the pixel prediction techniques used in the proposed cryptanalysis schemes.
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Chen, Ji-Tian, and 陳吉田. "Fast Image Encryption Technique for H.261 Video System." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/57512107312564452704.
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LIU, SHANG-SHIN, and 劉尚鑫. "Reversible Data Hiding and Image Encryption in Frequency Domain." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/z9quac.
Full textAbstract:
碩士國立屏東大學
資訊科學系碩士班
105
In recent years, the transmission of information has become more and more widespread. Open and widespread network has become a public contact pathway with each other. In the convenient and rapid times, the danger behind the network is the security issue of information transmission. Mostly, we do not know where the on-hand media files come from. The condition of knowing to use but knowing the source is growing. In this situation, it may that we have accidentally offended against the law but we do not know. Therefore, many people claim that they hold the files at first hand by illegal methods. How to protect the transmission of information and authenticate the message is an important thing obviously. In this thesis, we propose a reversible data hiding and image encrypting method in the frequency domain. We use the wavelet transform to transfer images from the spatial domain into the frequency domain, and encrypt the vision-sensitive low band using the RC4 stream cipher. Then, the secret message is reversibly embedded into the middle and high bands by the PVO approach and the middle and high bands are permutated to increase security. Finally, the processed results are compressed by the ZIP method. Experimental results show that our proposed method has nice encrypted effect in vision and can extract hidden hiding data correctly.