Algorithm Research On Text Information Hiding Based On Transform Domain

With the development of Internet, the transmission of information exchange becomes more and more quick and convenient than ever before. It also brings great hidden dangers into information security. It is an issue worthy of exploration how to tranfer secret text which is the most important information through network safely, imperceptibly and conveniently. The technology of information-hiding makes up the deficiencies of encryption technology that exposing senders, secret text and communication. It is the basic protectionit to secret information and not only hides information, but also the existence of information.In order to enhance the security of confidential information, the secret text is scrambling and the pseudo-random position is selected when embedded. An algorithm of pseudo-random selection and scrambling with address malposition is proposed on the basis of the independence between sequence and address. It makes up the deficiencies of the pseudo-random algorithms of selecting interval position and replacing position based on MD5. The new algorithm is proved by experiment that dimension scalability, distribution adaptability and security are all improved. It also can be embedded by full capacity.With the analysis of transform domain characteristics of audio, image and text, the algorithms are optimized. Three classical algorithms are researched: quantify coding the interval sequence of audio carrier, amending the relative amplitude of the transform domain coefficients of image carrier, encoding transform domain coefficient as keys in text vector. The optimized algorithms have been improved better then before: increasing hidden capacity; enhancing the robustness and transparency of the secret information; optimizing the process of the transform domain algorithms; improving flexibility and adaptability when used to covert communications practice.According to JPEG compression process and JND principle, it is proposed that a new blind-hiding algorithm based on the parity quantifing and amendment in transform domain. This algorithm with a special parity quantifing method has been proved strong robust and unsensible. The bit error rate which is caused by sender can also be decreased or eliminated.Finally, a model of covert communication is structured to meet application requirements on the basis of the algorithm research on text information hiding.