The Research Of Information Hiding And Information Detection Based On Digital Image

The technique of information hiding and information detection which has developed since mid to late 1990s is one of the new cross subjects in information security field. In this thesis,the main contents are techniques of information hiding and information detection,in which the digital images are applied as carriers.The basic concepts and theories of image information hiding are analyzed and summarized in this thesis. On the basis of the current information hiding algorithms, an LSB algorithm for hiding large capacity of information based on blocks is presented. Taking full advantage of all kinds of masking characteristics of human visual system,the method embeds secret information self-adaptively. With the method,good invisibility can be achieved,and the hiding capacity of information is large. In order to protect the copyright of the image in the condition of the unchanged image quality and in light of the masking characteristics of human vision system,a DCT algorithm for good robustness is presented. This method shows that good invisibility can be achieved and the robustness is good.Information hiding and information detection are two opposite aspects. Therefore,the basic idea and theories of image information detection are analyzed and studied in this thesis. On the basis of the current steganalysis algorithms,an image steganalysis which is an effecient universal detection methold with high accuracy is presented. The statistical features of high frequency wavelet sub-band coefficients of natural images and stego-images are analyzed, and the feature vectors are extracted from the texture statistical moment, the DCT coefficients' histogram moment and correlativity between blocks, and then the stego-images are classified by the SVM method. The proposed steganalysis algorithm extracts multiple features from different types and perpectives, thus solving the insufficiency of feature extraction in current universal steganalysis methods. The proposed steganalysis algorithm can detect illegal images on internet.The results of the study and experiments in this thesis show that the performance indicators of the hidding capacity,invisibility and robustness are relative,so the better performance of one indicator may cause the worse performance of the others.In different applications,the technique of information hiding requires different performance indicators. And which indicator should be strengthened depends on the actual situation.