Research On The Security Of Information Hiding

Information hiding, originating from the ancient Greek art "covered writing", is anemerging science of invisible communication. It aims to hide the very existence ofsecret message by embedding them into innocuously looking cover data. Informationhiding can be used for the different purposes ranging from covert communication,copyright protection, data authentication and some other special applications. Similarto cryptography, information hiding is a "mouse and cat" game. Much moreattention has been paid in the security, which means the tradeoff between theperceptual transparency, robustness and payload (capacity). This dissertationconveyed research on security of information hiding in the four aspects: thetheoretical model, the evaluation, the attack of information hiding and some newpractical novel schemes of steganography and steganalysis. The main contributions ofthis dissertation are recapitulated as follows.About the theory model of information hidingA mathematic model, an information-theoretic definition of perceptual transparencyand robustness and a game theoretic conditional analysis of the payload are presentedin this thesis, forming the theoretic basis of design of information hiding. Based onthe deep understanding the mechanism of the information hiding, the concept of thegeneralized information hiding is also suggested in this paper. The perceptualredundancy that provides accommodation for information hiding can be interpreted asthe unharmonious between the recording objective information and sensing subjectiveinformation.About how to evaluate the information hidingThe main evaluation schemes of information hiding including the objective evaluationand subjective evaluation are discussed. The limitation of PSNR evaluation method,which is most frequently applied in evaluation system, is given in the paper. A morereasonable distortion measure evaluation combined with the image complexity isproposed here. There is much influence of the image complexity on vision feeling,while less work has been done in complexity definition. A sound complexity notion isdefined according to the information entropy using run-length measure method. Inorder to give a quantificationally analysis of complexity, the run-length probabilitydistribution of random sequence is deduced. The adjacency degree between therun-length probability distribution of image plane and that of random sequence is usedto describe the complexity.About attack of the information hidingThe most typical attack mode and the practical checking method of informationhiding are outlined in the dissertation. It is pointed out that the secure embeddingscheme is based on strategy of eluding typical attack method. A secure paradigm ofinformation hiding against cover-stego-attack, which is fulfilled by simulating naturaloperation, is suggested and novel scheme to realize this secure paradigm in binaryimages using scanning operation is also proposed here. A more efficient practicalmethod is fulfilled based on morphological theory. The matrix encoding is applied toincrease the embedding capacity.Binary image steganalysisA considerable amount of attention has been lately paid to steganalytic technique ofcolor images, however few of them can be directly applied in binary images. Thispaper presents two novel steganalytic methods that can reliably detect messageshidden in binary image. The first method is able to detect as low as 1% embeddingrates in a binary image steganography using fixed partitioning embedding method.The key element of this scheme is the estimation of the original image, which is doneby filtering the stego-image with morphological operations. The second steganalyticscheme is to detect the message embedded in facsimile using run-length modificationmethod. That detection is based on modeling the run-length probability transformationbefore and after data embedding with the Markov model. Experimental resultindicates that relative modifications as small as 10% of usable run-length can bereliably detected.Finally, a summary of the research achievements on information hiding security isclassified. Some new directions of information hiding that need to be further exploredare also pointed out.