Steganography Algorithms Based On Image Difference And The Tool For The Detection Of S-tools

Information hiding is a new information security technology, which is based on the improvement of computer theory, information processing and network communication. It combines many subjects together, carries secure secret communication and has got fast improvement since 1980's.At present, steganography and digital watermarking are the problems which are investigated more widely and ardently in this field.The fast progress of steganalysis has aroused the advancement of steganography, especially the algorithms based on the difference of statistical properties , which has challenged the security of steganography system. Now the research emphases of image data hiding is the steganalysis-resisting algorithm. It can be proceeded with two ways: the first , improving the steganographic algorithm aiming at the weakness of steganalysis ones; the second, trying to preserve the coherence of statistical properties before and after embedding data.This thesis is focused on improving the steganographic algorithm aiming at the weakness of steganalysis ones which can avoid detection, mainly including the following three facets:1 A new spatial steganographic algorithm based on image difference are proposed. Through analyzing the statistical distribution of image difference, basing on its symmetry of positive/negative and odd/even properties ,we build a data mapping method. According this, we can embed secret message into image difference data, then renew the image pixel value. The experiment results proves that this method can preserve the first-order statistical properties of the image , those steganalysis techniques against LSB-based algorithm cannot detect the existence of hidden data ,and the stego-image has very good visual effect.2 Through matrix coding , we embedded the message into the LSB of gray image .this way can mend the security of steganography system .For example, the high efficiency coding way reduces the changed bit number of the LSB plane ,so the stego-image has good visual quality ;on the other hand ,if one want to pick-up the message ,he needs to know the coding method ,this predicates another safeguard for the secret data .Both the theory and the experiment results has proved its high embedding efficiency.3 The S-tools is taken part and its data embedding principle has been explained .The images which have data to embedded in are analyzed .we find some statistical properties changed after embedding .The change becomes the base for the further work.We also introduce and contrast some steganographic and steganalysis methods which are in common use .At last, we summarize our work and discuss the further research topics anddirections in the future.