This thesis focuses on video watermarking robust against geometric attacks and video compressions. In addition to the requirements for an image watermarking algorithm, a digital video watermarking algorithm has to be robust against advanced video compressions, frame loss, frame swapping, aspect ratio change, frame rate change, intra- and inter-frame filtering, etc. Video compression, especially, the most efficient compression standard, H.264, and geometric attacks, such as rotation and cropping, frame aspect ratio change, and translation, are considered the most challenging attacks for video watermarking algorithms. In this thesis, we first review typical watermarking algorithms robust against geometric attacks and video compressions, and point out their advantages and disadvantages. Then, we propose our robust video watermarking algorithms against Rotation, Scaling and Translation (RST) attacks and MPEG-2 compression based on the logpolar mapping and the phase-only filtering method. Rotation or scaling transformation in the spatial domain results in vertical or horizontal shift in the log-polar mapping (LPM) of the magnitude of the Fourier spectrum of the target frame. Translation has no effect in this domain. This method is very robust to RST attacks and MPEG-2 compression. We also demonstrate that this method can be used as a RST parameters detector to work with other watermarking algorithms to improve their robustness to RST attacks. Furthermore, we propose a new video watermarking algorithm based on the 1D DFT (one-dimensional Discrete Fourier Transform) and 1D projection. This algorithm enhances the robustness to video compression and is able to resist the most advanced video compression, H.264. The 1D DFT for a video sequence along the temporal domain generates an ideal domain, in which the spatial information is still kept and the temporal information is obtained. With detailed analysis and calculation, we choose the frames with highest temporal frequencies to embed the fence-shaped watermark pattern in the Radon transform domain of the selected frames. The performance of the proposed algorithm is evaluated by video compression standards MPEG-2 and H.264; geometric attacks such as rotation, translation, and aspect-ratio changes; and other video processing. The most important advantages of this video watermarking algorithm are its simplicity, practicality and robustness.

Este trabajo presenta tanto el estado del arte como el análisis de las principales propuestas de protección de agentes móviles frente a los ataques de la plataforma de ejecución. La comprensión del problema de los hosts maliciosos y la dificultad que presenta su resolución es importante para entender que todavía no exista una propuesta que dé solución global a dicho problema. Esto sin duda está limitando el uso de los agentes móviles en sistemas abiertos como Internet.Esta carencia en el ámbito de la seguridad nos ha motivado a desarrollar nuevas propuestas de protección de agentes. Dado que consideramos que las propuestas que tratan de evitar los ataques son demasiado costosas computacionalmente o imposibles de implementar en un sistema real, centraremos nuestros esfuerzos en propuestas que traten de detectar ataques. En ese sentido, se introducen tres nuevas aportaciones que pretenden contribuir a solucionar el problema de los hosts maliciosos. Como primera contribución de la Tesis se introduce un Protocolo de Detección de Sospechosos (SDP) para mejorar algunos aspectos de la propuesta de detección de ataques más conocida, la de las trazas criptográficas de Vigna. No sólo se ha realizado el estudio teórico de SDP, sino que se dispone de una implementación con la cual se han podido realizar pruebas del coste que supone, con resultados positivos. Sin embargo, consideramos que el anterior mecanismo conjunto todavía es demasiado costoso computacionalmente. Por esa razón y como segunda contribución se presenta un mecanismo propio de detección de ataques alternativo al anterior y más ligero computacionalmente. Dicho mecanismo está basado en el empotrado de marcas de agua en el agente, esto es, Watermarking de Agentes Móviles (MAW). Dado que los mecanismos de detección son poco útiles si no hay posibilidad de castigar a los hosts maliciosos, como tercera contribución se presenta una nueva entidad sancionadora, la Autoridad de Revocación de Hosts (HoRA).La implementación de la HoRA está todavía en desarrollo, con lo cual no se han podido realizar las pruebas de evaluación del rendimiento.

The objective of this thesis is to present a robust watermarking algorithm for H.264 and to address challenges in compressed-domain video watermarking. To embed a perceptually invisible watermark in highly compressed H.264 video, we use a human visual model. We extend Watson's human visual model developed for 8x8 DCT block to the 4x4 block used in H.264. In addition, we use P-frames to increase the watermark payload. The challenge in embedding the watermark in P-frames is that the video bit rate can increase significantly. By using the structure of the encoder, we significantly reduce the increase in video bit rate due to watermarking. Our method also exploits both temporal and texture masking. We build a theoretical framework for watermark detection using a likelihood ratio test. This framework is used to develop two different video watermark detection algorithms; one detects the watermark only from watermarked coefficients and one detects the watermark from all the ac coefficients in the video. These algorithms can be used in different video watermark detection applications where the detector knows and does not know the precise location of watermarked coefficients. Both watermark detection schemes obtain video watermark detection with controllable detection performance. Furthermore, control of the detector's performance lies completely with the detector and does not place any burden on the watermark embedding system. Therefore, if the video has been attacked, the detector can maintain the same detection performance by using more frames to obtain its detection response. This is not the case with images, since there is a limited number of coefficients that can be watermarked in each image before the watermark is visible.

In recent years, digital watermarking technique has become the most useful method for protecting the ownership of a user's digital content, and it can be used to verify ownership by embedding a user's digital watermark into that digital content. By showing the watermark, someone can prove legal ownership of the intelligent property on the digital content. Because of the maturity of e-commerce on the Internet, users can purchase digital content through buyer-seller watermarking protocols, and these protocols can help users to embed their watermarks into their digital content. After the transaction is terminated, users can also obtain their own digital content with the desired watermark embedded. However, when users attempt to exchange their digital content with each other over a network, it is important that a secure and efficient method be used. If users directly execute one of the above buyer-seller watermarking protocols, they will find that it cannot achieve significant transfers of digital content. On the other hand, they cannot be guaranteed that the transaction will be fair and efficient. Besides, when users are located on different networks, it is important to understand how they can obtain a protocol that is fair and efficient. To address these problems, we propose efficient and fair digital content exchange protocols for different networks such as Ethernets, P2P networks and cloud networks. Our proposed protocols can achieve identity authentication before performing the digital content exchange protocol, and can also maintain fair transactions between users. Finally, we also provide the formal security proofs for the proposed protocols and properties comparisons with other related schemes. Moreover, our protocols also offer solutions that are suitable for users who are located on different networks, and guarantee that digital content exchange transactions will be performed fairly and efficiently.

The major topic of this dissertation is how to improve the image quality and application of digital watermarking techniques. Most traditional digital watermarking techniques focus on the development and improvement of embedding algorithm. But fewer people really care about the degradation of the image quality of digital watermarking techniques. Meanwhile, the application of digital watermarking technique seems to be limited in the copyright protection. Therefore, the techniques used to improve the image quality and to expand the application of digital watermarking technique are proposed in this dissertation. The concept of the proposed technique used to improve the image quality of digital watermarking technique is different from the concept of traditional watermarking techniques which directly modify the features of image to embed digital watermark. Dissimilarly, the proposed technique uses the relation between the features to embed the digital watermark. In this way, the probability of modifying the feature can be efficiently reduced. Therefore, the image quality of watermarked image can be improved. Besides, the proposed technique works like a pre-process. The proposed technique can be easily applied to present traditional digital watermarking techniques without changing the original embedding and extracting process. The expansion of digital watermarking techniques application consists of two techniques. The first one uses the digital watermarking technique to provide the ¡§Image Refining¡¨ function for digital images. In the proposed technique, the RS (Reed-Solomon) codes of original image are used as a watermark and are embedded in the original image. The watermarking information can provide the error correction capability while the original image is distorted (refining function). If there is some alterations made to the watermarked image and they are within the error correction capability of the RS parities, the alterations will be corrected by the RS decoding to restore the original image. The second one applies the digital watermarking techniques on the Pay-TV system. Conventional key distribution methods used in Pay-TV system emphasize on the method¡¦s refinement in order to reduce the frequency of the keys distributed over network. The proposed method uses the digital watermarking technique to hide the cryptographic keys into routine encrypted video program without any increasing of video program size for the economy of network bandwidth and degradation in perceptual quality. The purpose of this thesis is to improve the practicability of digital watermarking techniques. The proposed techniques could supplement the incompleteness of the traditional digital watermarking techniques with additional functions and applications. In this way, traditional digital watermarking techniques can not only be used for copyright protection but also be the new choice of resolving problem in the future digital environment.

Thèse doctorat : Informatique : Villeurbanne, INSA : 2007. / Thèse rédigée en anglais. Titre provenant de l'écran-titre. Bibliogr. p. 139-147. Publications de l'auteur p. 133-134. Index auteurs.

Thesis (M.S.)--Mississippi State University. Department of Electrical & Computer Engineering. / Title from title screen. Includes bibliographical references.

Η προστασία των πνευματικών δικαιωμάτων και η απόδειξη γνησιότητας του κατόχου, επομένως και η πιστοποίηση της αυθεντικότητας των ψηφιακών αντικειμένων είναι ένα πολύ καυτό ζήτημα και για την επίλυσή του επιστρατεύονται μέθοδοι απόκρυψης πληροφορίας και τεχνικές υδατογράφησης. Εκτός από τη φιλοσοφική αντιμετώπιση του θέματος, προτείνονται μια μέθοδος απόκρυψης πληροφορίας και δύο τεχνικές υδατογράφησης, με σκοπό την προστασία των πνευματικών δικαιωμάτων και την πιστοποίηση της αυθεντικότητας των ψηφιακών αντικειμένων. Η μέθοδος απόκρυψης πληροφορίας δανείζεται έννοιες από την κρυπτογραφία εισάγοντας σε μεγάλες εικόνες ένα δύσκολο στιγμιότυπο, δηλαδή έναν τρία χρωματίσιμο γράφο. Ο γράφος μαζί με το χρωματισμό του αποτελεί το κλειδί. Για να μην αποκαλυφθεί όλος ο χρωματισμός του γράφου σε μια πιθανή διαμάχη, εφαρμόζεται το πρωτόκολλο των διαντιδραστικών αποδείξεων μηδενικής γνώσης (ZKIP) για δύσκολα υπολογιστικά προβλήματα. Η διαδικασία της ένθεσης γίνεται με χρήση του μετασχηματισμού wavelets, παρέχοντας καλή ποιότητα των παραγόμενων εικόνων και ανθεκτικότητα σε περιπτώσεις επιθέσεων. Οι δύο τεχνικές υδατογράφησης εφαρμόζονται στο χωρικό πεδίο και στο πεδίο συχνοτήτων, αντίστοιχα. Η τεχνική που εφαρμόστηκε στο χωρικό πεδίο εκμεταλλεύεται τυχόν ομοιότητες του υδατογραφήματος με τις αρχικές εικόνες για να επιλεγούν οι θέσεις ένθεσης. Αντίθετα στην τεχνική υδατογράφησης που εφαρμόστηκε στο πεδίο συχνοτήτων γίνεται χρήση του μετασχηματισμού wavelet. Σε όλες τις τεχνικές παρατηρήθηκαν ικανοποιητικά αποτελέσματα μετά την ένθεση της εισαγόμενης πληροφορίας έτσι ώστε να μη είναι οπτικά αντιληπτή. Επίσης εξετάστηκε και η ανθεκτικότητα της εισαγόμενης πληροφορίας στις εικόνες ύστερα από πιθανές επιθέσεις και επιβεβαιώθηκε ότι επιζεί ένα αρκετά μεγάλο ποσοστό της εισαγόμενης πληροφορίας, γεγονός που καταξιώνει τις προτεινόμενες μεθόδους. / The copyright protection and the authentication is a very hot topic and for its solution are called up data hiding methods and watermarking techniques. Αpart from the philosophical confrontation of the subject, there are proposed a data hiding method and two watermarking techniques that aim to copyright protect and the authenticate digital objects. The data hiding technique combines concepts from cryptography and it can be applied to large images by inserting a hard instance, i.e. a 3-colorable graph. The graph itself with its coloring compose the key. In order not to reveal all its coloring in a possible conflict, the Zero Knowledge Interactive Proof Protocol (ZKIP) is applied. The insertion process has been done using wavelets transformation, offering good quality of the produced images and robustness against possible attacks. The two watermarking techniques are applied in spatial domain and in frequency domain, respectively. The technique that was applied in spatial domain is exploiting any similarity between the watermark and the initial images so that to select at best the insertion positions. On the contrary, in the watermarking technique that is applied in the frequency domain, wavelets transformation has been used and the watermark was inserted in the differential coefficients of the image, in order to be imperceptible. To all the above techniques, it has been observed sufficient results after the insertion of the redundant information, so that it turned to be visible imperceptibly. Moreover, the robustness of the redundant information was each time after possible attacks examined, and it was confirmed that a rather big percentage of the redundant information is survived, making more reliable the proposed techniques.

Σκοπός της συγκεκριμένης εργασίας είναι η παρουσίαση των σημαντικότερων τεχνικών υδατογράφησης (watermarking techniques) ψηφιακών εικόνων με ανθεκτικότητα σε γεωμετρικούς μετασχηματισμούς και η περιγραφή και υλοποίηση ενός τέτοιου συστήματος. Οι γεωμετρικοί μετασχηματισμοί, στους οποίους δόθηκε περισσότερη έμφαση κατά την υλοποίηση του συστήματος υδατογράφησης ψηφιακών εικόνων που θα παρουσιαστεί παρακάτω, έχουν να κάνουν με την κλιμάκωση (scaling), την περιστροφή (rotation) και τον μετασχηματισμό συντεταγμένων (translation) μιας εικόνας καθώς επίσης και με συνδυασμούς αυτών. Παρόλα αυτά όμως το σύστημα που περιγράφεται αντιμετωπίζει σε ικανοποιητικό βαθμό και άλλες γεωμετρικές επιθέσεις (όπως shearing,aspect ratio change, projective, template remove κ.α.).Η ανθεκτικότητα ενός συστήματος υδατογράφησης σε αυτούς τους μετασχηματισμούς έχει να κάνει με την διατήρηση του υδατογραφήματος και την ικανοποιητική ανίχνευση του σε εικόνες που έχουν υποστεί τέτοιου είδους μετασχηματισμούς. Στην εργασία, αρχικά γίνεται μια εκτενής αναφορά στην τεχνική της υδατογράφησης και τις εφαρμογές της και έπειτα τονίζονται τα σημαντικότερα χαρακτηριστικά των συστημάτων υδατογράφησης ψηφιακού υλικού. Στη συνέχεια, ορίζονται οι γεωμετρικές επιθέσεις σε εικόνες και παρουσιάζονται οι σημαντικότερες μέθοδοι υδατογράφησης ψηφιακών εικόνων, που υπάρχουν στην βιβλιογραφία, με ανθεκτικότητα στις επιθέσεις αυτές. Στην εργασία αυτή υλοποιήθηκε μία από αυτές τις μεθόδους και έγινε προσπάθεια για επέκταση και βελτίωση της σε ορισμένα σημεία που υστερούσε. Η αρχική και βελτιωμένη μέθοδος περιγράφονται αναλυτικά. Στο τέλος ένας αριθμός πειραματικών αποτελεσμάτων αποδεικνύουν την ανθεκτικότητα του νέου βελτιωμένου συστήματος που υλοποιήθηκε σε ένα μεγάλο πλήθος γεωμετρικών επιθέσεων. / The aim of this work is the presentation of the most important watermarking techniques for digital images with robustness to geometric transformations and the description and implementation of such a system. The geometric transformations, to which was given more emphasis at the implementation of the digital images watermarking system, that will be presented below, are the scaling, the rotation and the transformation of coordinates (translation) of an image as well as the combinations of these. Nevertheless, the system that is described faces in satisfactory degree and the other geometric attacks (as the shearing, the aspect ratio change, the projective, the template remove etc.). The robustness of a watermarking system to these transformations it is simply translated as the maintenance of the watermark and its satisfactory detection in images that have existed such type of transformations. In this work, it initially becomes a extensive report to the watermark technique and to its applications and then the more important characteristics of digital material watermarking systems are highlighted. Afterwards, the geometric attacks of digit images are determined and the most important watermarking methods of digital images with robustness to these attacks, that exist in the bibliography, are presented. In this work, one of these methods was implemented and it became some effort for its extension and its improvement in certain points that disadvantages. The initial and improved methods are analytically described. At the end, a number of experimental results are presented, that they prove the robustness of the new improved system to a large number of geometric attacks.

Būtinybė apsaugoti autorinių teisių savininkus nuo neteisėto intelektinės nuosavybės naudojimosi ir platinimo vis didėja. Tam puikiai tinka skaitmeniniai vandens ženklai, kurie ne tik apsaugo nuo neleistino intelektinės nuosavybės naudojimosi, bet pasinaudojus vandens ženklais galima susekti neteisėtą vartotoją. Šiame darbe aptarta diskrečioji kosinuso transformacija (angl. Discrete Cosine Transform (DCT)) ir išplėsto spektro (angl. Spread-Spectrum) ženklinimo vandens ženklais metodai, plačiau išnagrinėtas DCT metodas ir patikrinta keletas paprastų vaizdo atakų, kaip antai: karpymas, suspaudimas, pasukimas ir pan. Dalies vaizdo iškirpimas, pasukimas gali neatpažįstamai pakeisti vandens ženklą. Taip nutinka, nes iš pakeisto paveikslėlio ištraukiant vandens ženklą priešingu įterpimui metodu pasikeičia vaizdo taškų koordinatės, o iškirpus dalies koordinačių trūksta. Priklausomai nuo posūkio kampo ar iškirptos dalies dydžio sugadinamas ir vandens ženklas, kuris nepasikeičia keičiant spalvą ar kontrastą. / The necessity to protect copyright owners from using and sharing illegal intellectual property still grows. Digital water marks fits perfectly for this matter. They not only prevent using illegal intellectual property, but they can also detect illegal user. In this paper the discrete cosine transform (DCT) and spread-spectrum water-marking methods were discussed, and DCT method was analysed, and several image attacks were tested, such as: trimming, compression, rotation and etc. The trimming a part of an image, rotation of an image can change water mark beyond recognition. It happens because taking water mark out from changed image using inverse method of insertion image pixel coordinates change, and trimming causes a missing of part of coordinates. Depending on the angle of rotation or the size of a trimmed part a water mark is corrupted, but it does not change when a colour or a contrast is being changed.