On Information Hiding Technology And Application

With the rapid development of Internet and the modern telecommunication technology, Digital information security has increasingly been cared. Since 1990', information hiding has become a hot field in the Society of information science and technology. The aim of information hiding is to hide the secret data into multimedia such as digital image, sound, video and etc. Information hiding can mainly be divided two branches: digital watermark and digital stenography. The aim of digital watermark is to protect the copyright of Digital works, it can be used to prove whether the secret data has been removed or changed. While the aim of digital stenography is that the secret information is hid into the data carrier and transferred through public channels for avoiding seen by the third party. Technologies for digital image hiding have recently been studied by many people and they are different from the traditional encrypting. The way of using delusion of digital image for data hiding can stand many hostile attacks. In this area, though many works have been down, a perfect one is still hardly to find. Commercial software packages which greatly depends on man-machine interaction sometimes yields undesired results. This thesis presents some effective and robust algorithms for Digital Image Hiding Technology on the base of the predecessors' work. The major works involved are as follows:1. By using of chaotic sequence and symmetric block cipher scheme (named ZF-02), a new scheme of scrambling is provided. In this scheme the chaotic sequence is used to give original cipher, which can control both complex transposition permutations of input and of output. Advantages of the cipher algorithm of ZF-02 are that it can resist several attacks and is easy realized by both software and hardware.2. By using of the idea of digital image's information sharing, a new blendingapproach based on RB curve is presented. The approach makes use of a n-degree 3rational Bezier curve or a k-OTder-[n/n] RB curve or a [?/?] RB curve with weights to hide information of one image into information of n images. These blending schemes have more blending parameters to act as the private keys, which can enhance the security and robustness of the hiding image more. Furthermore, the schemes can be combined with the scrambling technology, which is usually used as pre-process and post-process of digital image information hiding. Examples show that these schemes can be realized expediently and have some degree of robustness. These blending schemes can also be used in the field of digital watermarking and other digital application.3. Considering the block effects of image-hiding in DCT domain and the characteristics of human vision system, a new scheme of image hiding is provided using of chaotic sequence and the characteristics of human vision system. In this scheme the chaotic sequence is used as blending parameters. According to the frequency response of human vision system, one image is classified into many different blocks. Because different blocks is blended with different parameter, image quality can be guaranteed. Results of analytic experiments show that not only this scheme of digital image information hiding can be easily realized and is effective, but also the algorithm is robust and can resist many attacks such as cropping.4. Blending between DCT coefficients of the secret image and DWT coefficients of the public image can cause the new image with the secret image' profile, and due to the block effect and mosquito noise of DCT, so we can Jiide DCT coefficients of the secret image into DWT field of the public image. Examples show that the scheme can be effective .The algorithm has some degree of robustness and it can resist many attacks.