Theory And Algorithms For Information Hiding In Digital Image

In the most of modern communication systems, the security of the traffic primarily depends on the cryptography, but this has rarely been adequate in practice by merely concealing the content of a message using encryption because the encryption may attract the attacker's attention, and then invokes attack. Information hiding techniques have recently become important in a number of application areas. In contrast to cryptography, it seeks to conceal the sender, the receiver or the very existence of a message, rather than merely concealing its content.The most concerned aspects of information hiding are, as to say, the ability to endure detecting or imperceptibility, the embedding capacity and the robustness, In general, these three aspects of information hiding are inconsistent to each other and can't get perfect performance independently. In practice, the imperceptibility and capacity are more important when you want to embed average information such as a picture, while you want to hide important information such as military applications, the robustness is more important. In this dissertation, we study the technologies and application of these two situations, our attentions focused on image scramble, image hiding, hiding analysis and attack.The contributions of this dissertation in theory include:(1) The integer version of data processing is studied systematically.A method to construct an integer version of the linear transforms is presented so that the integers of input data can be mapped to integers. Based on the introduction of three kinds of basic integer reversible transform, it is proposed by means of matrix decomposition the sufficient and essential condition that a linear transform can be rebuilt into integer version and the corresponding construction method. The transform is reversible, so it is suitable for the lossless data processing such as the lossless digital audio or image compressions.(2) The construction of module affine transformation.The concept of Generalized Fibonacci Queue is presented, based on which, the construction of module affine transformation is resolved.The contributions of this thesis in application include:(1) Digital image scrambling techniquesAs a kind of encryption method, the importance of image scrambling technique in information hiding is explored. The definitions of image scrambling, image scramblingdegree and periods of image scrambling are proposed. Three novel image-scrambling algorithms are proposed, and their performances of scrambling image are analyzed.The quasi-anti-order scrambling and quasi-dither scrambling have ideal scramble performance, and can enhance the anti-analysis performance of an information hiding system.Quasi-Affine Transformation Over Limited Integer Grids (QATLIG) is present, based on the idea of building reversible linear transform that mapping integers to integers. QATLIG has a larger periods and leads to a better result, so it is superior to Arnold transformation, Fibonacci transformation and other geometric transformations.(2) Information hiding technique in digital imageThe classification and the basic algorithms of information hiding are introduced. We focused on two kinds of applications, hiding algorithms for image embedding and algorithms for general important information embedding. In general, the first one request high-embedding capacity but the second demands robustness.In practice, the 'blind extraction' is another demand for image embedding, which ensure the simplicity of the communication procedure. We propose a new algorithm, which enhance the blind performance greatly.As above 95% of images are compressed for storage and transfer, data compression techniques are combined with information hiding algorithms. A general information-hiding model based on data compression is proposed, we researched the key problems in this model, change the statistic properties of embedded data under the restriction of no data inflation and enhance the ability of anti-detection.