The Research And Application Of Secure Digital Steganographic Algorithm

Military and government departments, enterprises and individuals are very concerned about the security of the classified information during transmission and storage. To ensure the security of the classified information during transmission on networks and other channels is very important in the time which communication is becoming more and more developed. Because the encryption technology can not hide the existence of secret information, easily arouse suspicion, attacks, sabotage and even the secret information may be cracked. Fortunately, Information Hiding can make up the deficiencies of the encryption technology, so it has an urgent need and a broad prospect in the security covert communications.First and foremost, this thesis outlines the current status of Information Hiding in covert communication, analyses the existing problems of the steganography in digital medium, and emphasizes the importance of the security steganography and its faced challenges. Then it introduces the basic principles, methods and protocols of Information Hiding, and deeply studies the security theory and the safety evaluation of steganographic algorithms, specially the major evaluation indicators and evaluation methods for the perception of the hidden information. After the study, a strategy about how to improve the ability to resist detection is provided. What is more, the thesis investigates the present status of steganography and steganographic analysis in wavelets domain of pictures, in order to enhance its security, it provides a new algorithm in which data are embedded in middle frequency DWT coefficients between theθand (?), what is more, the statistical properties of the picture's histogram are nearly kept. This method can not only resist spectrum analysis and energy difference analysis, but also resist compressing code. Compared with other methods in wavelets domain of pictures, the security of this algorithm is obviously improved. Finally, based on the security research of algorithm, a safer and flexible steganography system is designed and carried out according to the need of security covert communication applications. At last, this thesis makes a conclusion, and some new directions that need to be further explored are also pointed out.