General Framework of Reversible Watermarking Based on Asymmetric Histogram Shifting of Prediction Error

This paper presents a general framework for the reversible watermarking based on asymmetric histogram shifting of prediction error, which is inspired by reversible watermarking of prediction error. Different from the conventional algorithms using single-prediction scheme to create symmetric histogram, the proposed method employs a multi-prediction scheme, which calculates multiple prediction values for the pixels. Then, the suitable value would be selected by two dual asymmetric selection functions to construct two asymmetric error histograms. Finally, the watermark is embedded in the two error histograms separately utilizing a complementary embedding strategy. The proposed framework provides a new perspective for the research of reversible watermarking, which brings about many benefits for the information security

FRAGMENT-VISIBLE MOSAIC IMAGES BY COLOR TRANSFORMATIONS

The variety image, which looks much like a randomly selected target image and can be utilized like a camouflage from the secret image, is produced by dividing the key image into fragments and changing their color qualities to become individuals from the corresponding blocks from the target image. Existing data hiding techniques mainly make use of the techniques of LSB substitution, histogram shifting, difference expansion, conjecture-error expansion, recursive histogram modification, and discrete cosine/wavelet changes. A brand new secure image transmission strategy is suggested, which transforms instantly confirmed large-volume secret image right into a so-known as secret-fragment-visible variety image of the identical size. Skilled techniques are made to conduct the color transformation process so the secret image might be retrieved nearly lossless. A plan of handling the overflows/underflows within the converted pixels’ color values by recording the color variations within the untransformed color space can also be suggested. The data needed for recuperating the key image is embedded in to the produced variety image with a lossless data hiding plan utilizing a key. Good experimental results show the practicality from the suggested method. Within the first phase, a variety image is produced; featuring it’s the fragments of the input secret image with color corrections based on a similarity qualifying criterion according to color versions

fast estimation of optimal marked-signal distribution for reversible data hiding

Recently, code construction approaching the rate-distortion bound of reversible data hiding has been proposed by Lin , in which the coding/decoding process needs the optimal probability distribution of marked-signals as parameters. Therefore, the efficiency and accuracy of estimating the optimal marked-signal distribution will greatly influence the speeds of encoding and decoding. In this paper, we propose a fast algorithm to solve the optimal marked-signal distribution. Furthermore, we modify the method to achieve the optimal distribution directly according to a given distortion constraint or an expected embedding rate, which makes it more practical for applications. © 2005-2012 IEEE.Recently, code construction approaching the rate-distortion bound of reversible data hiding has been proposed by Lin , in which the coding/decoding process needs the optimal probability distribution of marked-signals as parameters. Therefore, the efficiency and accuracy of estimating the optimal marked-signal distribution will greatly influence the speeds of encoding and decoding. In this paper, we propose a fast algorithm to solve the optimal marked-signal distribution. Furthermore, we modify the method to achieve the optimal distribution directly according to a given distortion constraint or an expected embedding rate, which makes it more practical for applications. © 2005-2012 IEEE

Şifreli ve şifresiz videolar için yinelemeli histogram değiştirme tabanlı tersinir video damgalama

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Bu tezde şifresiz ve şifreli videolar için tersinir video damgalama yöntemleri geliştirilmiştir. Her iki durumda da, video çerçeveleri arasındaki zamansal ilinti, hareket dengelemeli çerçeve aradeğerlemesi kullanılarak değerlendirilmiş ve damgalamada görüntüler için geliştirilmiş yinelemeli histogram değiştirime yönteminden faydalanılmıştır. Her bir çerçeve için tersinirliğin garanti edilmesi ve toplam kapasitenin çerçevelere eşit bir biçimde dağıtılması problemlerinden dolayı yinelemeli histogram değiştirme yöntemi tersinir şifresiz video damgalamada doğrudan kullanılamaz. Bu tezde, bu iki problemin çözümünde özgün fikirler önerilmiştir. Önerilen yöntem, literatürde sıklıkla kullanılan video dizilerinde test edilmiş ve yöntemin mevcut tersinir şifresiz video damgalama yöntemlerinden kapasite ve bozunum performansı bakımından daha iyi sonuçlar verdiği bilgisayar benzetimleri ile gösterilmiştir. Şifreli videolar için geliştirilen yöntemde, damgalama için çerçevede gerekli olan boşluk şifreleme öncesi oluşturulmaktadır. Boşluk oluşturma işlemi, orijinal çerçevedeki belirli piksellerin en düşük anlamlı bitlerinin ilgili çerçevenin hareket dengelenmiş aradeğerleme hatalarına yinelemeli histogram değiştirme yöntemi ile saklanması ile gerçekleştirilir. Damganın boşluk oluşturulmuş şifreli çerçevedeki piksellerin en düşük anlamlı bitleri ile yer değiştirilmesi ile damgalama işlemi tamamlanır. Orijinal video bir şifreleme anahtarı ile şifrelenir ve şifrelenmiş video bir damgalama anahtarı ile damgalanır. Damganın çıkartılması ve şifrenin çözülmesi işlemleri birbirinden bağımsız bir biçimde gerçekleştirilebilir. Her iki anahtarın bilinmesi durumunda damga ve orijinal video kayıpsız geri elde edilebilmektedir. Sadece damgalama anahtarının bilinmesi durumunda damgalanmış şifreli videodan damga çıkartılabilmekte fakat videonun içeriğine erişilememektedir. Sadece şifreleme anahtarı bilindiğinde ise damgaya erişilmeksizin orijinal videonun bozunumlu bir versiyonu elde edilebilmektedir. Bilgisayar benzetimleri önerilen yöntemin tersinir şifreli video damgalama uygulamalarındaki kullanılabilirliğini kanıtlamaktadır.In this thesis, reversible video watermarking methods are developed for plain and encrypted video. In both cases, temporal correlation among frames in the video are exploited by using motion compensated frame interpolation and recursive histogram modification algorithm developed for images are used in watermarking. The recursive histogram modification can not be used directly for reversible plain video watermarking because of the important problems of ensuring reversibility for each frame and distribution of total capacity among frames. In this thesis, novel ideas are proposed to solve these two problems. The proposed method is tested on the video sequences commonly used in the literature. It is shown to give better performance than the existing reversible plain video watermarking algorithms in terms of capacity and distortion by means of computer simulations. In the method developed for encrypted video, room required for the watermark is created before encryption. The room creating process is achieved by embedding the original least significant bits of some pixels of the frame into the corresponding motion compensated interpolation errors through recursive histogram modification. Watermarking is carried out by replacing the least significant bits of the pixels in the room reserved encrypted frame by the watermark bits. The original video is encrypted with an encryption key and the encrypted video is watermarked with a data hiding key. Watermark decoding and video decryption operations can be performed independently. The original video can be restored and the watermark can be decoded without error from the watermarked encrypted video if both keys are known. The watermark can be decoded from the the watermarked encrypted video but video content can not be accessed when only the data hiding key is known. A video signal close to the original one can be obtained without having access to the watermark when only the encryption key is available. Computer simulations prove applicability of the method in encrypted domain reversible video watermarking applications

Tersinir video damgalama

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Bu tezde, sayısal bir videoda arka arkaya gelen çerçeveler arasındaki zamansal ilintiden faydalanan tersinir iki video damgalama algoritması geliştirilmiştir. İlk algoritma, hareket dengelenmiş zamansal aradeğerleme hatalarının genişletilmesine dayalıdır. Yöntemde, damaga çıkartma ve orijinal videoyu geri elde etmek için gereken yan bilgi miktarı oldukça azdır. İkinci algoritma, hareket dengelenmiş öngörü hatalarının genişletilmesine dayalı uyarlanır bir yöntemdir. Öngörü hatalarının aldığı değerlerden bağımsız olarak, hareket dengelenmiş öngörü çerçevelerindeki tüm bloklara aynı damgalama algoritmasını uygulayan mevcut tersinir video damgalama yöntemlerinin aksine, ikinci algoritma öngörü hatalarının aldığı değerlere göre blokları farklı iki şekilde damgalamaktadır. Bu amaçla, bloklar düzgün ve düzgün olmayan şekilde iki sınıfa ayrılmıştır. Düzgün blokların belirli piksellerine 2-bit damgalama, düzgün olmayan blokların belirli piksellerine ise 1-bit damgalama uygulanarak damgalama kapasite arttırılmıştır. Ayrıca, yüksek bozunuma sebep olan pikseller belirlenip bu pikseller damgalamada kullanılmayarak damgalama sonucu orijinal videoda oluşan bozunum azaltılmıştır. Geliştirilen yöntemlerin, litaratürdeki mevcut yöntemlere göre kapasite ve orijinal videoda oluşan bozunum bakımlarından üstün olduğu bilgisayar benzetimleriyle gösterilmiştir. Geliştirilen algoritmalar birbirleriyle de karşılaştırılıp üstün ve zayıf olduğu yönler belirlenmiştir.In this dissertation, two reversible video watermarking algorithms exploiting temporal correlation existing among consecutive frames in digital videos were developed. The first algorithm is based on motion-compensated temporal interpolation error expansion. The algorithm has a low amount of side information required for watermark decoding and video restoration. The second algorithm is an adaptive method based on motion-compensated prediction error expansion. Unlike the current reversible video watermarking algorithms that apply the same watermarking method to all blocks in the motion-compensated prediction frames, the second algorithm watermarks the blocks with two different methods depending on their motion-compensated prediction errors. Blocks were classified as smooth and non-smooth for this purpose. Watermarking capacity was increased by applying a 2-bit watermarking strategy to some pixels of smooth blocks and a 1-bit watermarking strategy to some pixels of non-smooth blocks. Furthermore, pixels causing high distorttion were detected and they were not used during watermarkin to minimize the distortion occuring in the original video as a result of watermarking. Both algorithms were shown to be superior to the existing reversible watermarking algorithm in terms of capacity and distortion occuring in the original video by means of computer simulations. Both algorithms were also compared to each other and their strong and weak aspects were determined

Privacy-preserving information hiding and its applications

The phenomenal advances in cloud computing technology have raised concerns about data privacy. Aided by the modern cryptographic techniques such as homomorphic encryption, it has become possible to carry out computations in the encrypted domain and process data without compromising information privacy. In this thesis, we study various classes of privacy-preserving information hiding schemes and their real-world applications for cyber security, cloud computing, Internet of things, etc. Data breach is recognised as one of the most dreadful cyber security threats in which private data is copied, transmitted, viewed, stolen or used by unauthorised parties. Although encryption can obfuscate private information against unauthorised viewing, it may not stop data from illegitimate exportation. Privacy-preserving Information hiding can serve as a potential solution to this issue in such a manner that a permission code is embedded into the encrypted data and can be detected when transmissions occur. Digital watermarking is a technique that has been used for a wide range of intriguing applications such as data authentication and ownership identification. However, some of the algorithms are proprietary intellectual properties and thus the availability to the general public is rather limited. A possible solution is to outsource the task of watermarking to an authorised cloud service provider, that has legitimate right to execute the algorithms as well as high computational capacity. Privacypreserving Information hiding is well suited to this scenario since it is operated in the encrypted domain and hence prevents private data from being collected by the cloud. Internet of things is a promising technology to healthcare industry. A common framework consists of wearable equipments for monitoring the health status of an individual, a local gateway device for aggregating the data, and a cloud server for storing and analysing the data. However, there are risks that an adversary may attempt to eavesdrop the wireless communication, attack the gateway device or even access to the cloud server. Hence, it is desirable to produce and encrypt the data simultaneously and incorporate secret sharing schemes to realise access control. Privacy-preserving secret sharing is a novel research for fulfilling this function. In summary, this thesis presents novel schemes and algorithms, including: • two privacy-preserving reversible information hiding schemes based upon symmetric cryptography using arithmetic of quadratic residues and lexicographic permutations, respectively. • two privacy-preserving reversible information hiding schemes based upon asymmetric cryptography using multiplicative and additive privacy homomorphisms, respectively. • four predictive models for assisting the removal of distortions inflicted by information hiding based respectively upon projection theorem, image gradient, total variation denoising, and Bayesian inference. • three privacy-preserving secret sharing algorithms with different levels of generality