Image Information Hiding And The Application Research In Military Concealment Communication

In recent years, with the rapid developments of the computers networks multimedia and digital signal processing technologies, the research of information hiding has become a hotspot again in technological fields. Information hiding technique has very wide applications. One of the applications of information hiding is concealed communication. Concealed communication has many advantages, for example, the concealment and safeties, compared with traditional communications. It, therefore, becomes important particularly in national security and military section. In this thesis is presented some studies of arithmetic for image information hiding based on discrete cosine transform and the applications of image information hiding in military concealed communication system.The main contents of this thesis are as the follows. The fundamental techniques and technologies of information hiding are introduced. Digital watermark, one of the important branches of information hiding, is also introduced. The arithmetic of image information hiding using discrete cosine transform (DCT) is analyzed. It is found that the information hidden by the arithmetic is not large enough, nor safe, nor satisfactory to military concealed communications. For this reason, a betterment to increase the amount of information data hidden is proposed. In the betterment, first, the decimal part of DCT coefficients are modified dynamically to embed binary information. Secondly, the embedding bits are selected according to the sign and boundary of the DCT coefficients, the first bit of the binary information, and the last bit of the last embedded information. Thirdly, bitmaptemplet matching technique is improved to embed information. The arithmetic is suitable for concealed communication and characterized by larger amount of information hidden, robustness, visibility and security. The security is first decomposed into 24 bitmap to obtain the components of blue, green and red. Then the components of green and red are decomposed to obtain 16 bicentric image. 8 x 8 DCT of the component of blue is carried out. Next, secret information is taken to match with the 16 bicentric image. The matched part completely becomes the code for decoding the secret information. The mismatched part is embedded in the DCT coefficients through amending the decimal part of DCT coefficients. The result and data are given finally. Design of a military concealment communication system using information hiding technique is presented. The principle of design and frame constitution, main functions, tools for exploitation and running environments are put forward.The innovations in this thesis include:1 A way is proposed to embed the hiding information by amending dynamically the part of decimal fraction of DCT coefficients. Secret information is embedded dynamically into the decimal fraction or the first bit of the decimal fraction of the DCT components based on the integer of the DCT coefficients. The amount of hidden information is increased compared with other methods.2 A way is proposed to choose the embedding bit according to the value of the polarity and boundary of DCT coefficients, the first bit of the bicentric hiding information sequence and the last embedded bit. The amount of hidden information is increased by the choices of embedded 2 or 3 bits in one DCT coefficients.3 Matching technique is proposed in the arithmetic of information hiding. The arithmetic is based on bitmap templet matching and amends the decimal fraction of the DCT coefficients dynamically and randomly. Before embedding the secret information in the carrier image, the templet and the image are preprocessed, then some secret information are chosen as a template to match with the carrier image. The matched part becomes the code for decoding the hidden information, themismatched part is embedded into the blue component of the image.