Research On Theory And Application Of Steganogralhy Based On Error-Correcting Code

Information hiding is a developed technique in the field of information security including covert communication and copyright rotection of digital meidia, and has received significant attention from both industry and academia. Error-correction code is one kind of encoding data with strict mathematical structure, in which the redundant data is added to improve the reliability of communication. By applying the error map within the error-correcting-capability to information hiding, and using shared key to achieve a perfect secure information hiding system, the encoding redundancy has become a new resource for carrying secret message. Digital media decompose data in company with the shared key data compose the error-correcting encoding data. Digital media decomposing data and the checked data of the codeword composed the part of the error-correcting codeword to carry secret messages with its error map. Without shared key the embedded secret message could not be recovered.This thesis focused on stanganography theory based on error-correcting code and its applications. It closely keeps up with international research progress on steganographic techniques.The main contributions of this thesis are summarized as follows:(1) The technique of error-correcting encoding and image steganography is combined to form a new perfect secure steganography system. A novel theoretical model for information hiding based on the encoding redundancy of error-correcting code is proposed.(2) By the research of the encoding mechanism and performance of error-correcting code, the information hiding theory based on completely error-correcting codeword and part of the error-correcting codeword are proposed. A mapping code between secret message and codeword error map is built. By modifying the whole or part of the error-correcting codeword according to the error map the secret messages can be embedded. Some new steganographic methods based on error-correcting code such as Hamming code, Golay code and RS code are given. Those new approaches are applicable for both spatial and transform domain embedding.(3) According to the steganography theory based on error-correcting code, the calculation algorithm of embedding capacity for the proposed methods is given. By studying the security of error-correcting code based information hiding method, a perfect secure steganography system is proposed. Without shared key anyone could not extract the embedded secret message. Analytic results show the superiority of shared key steganography method based on error-correcting code over than steganography method based on error-correcting code.(4) A new semi-fragile watermarking scheme is proposed and realized using the RS error-correcting code and wavelet decomposition. While the encoding data of RS code are composed of an authentication key and selected wavelet data of an image, the checked data of RS code carry the watermark and are embedded into different sub-bands in the wavelet domain of the cover image, achieving semi-fragility. Theoretical analysis indicates that the proposed scheme is capable of identifying the authenticator with the authentication key data.There are a lot of error-correcting codes. Selecting an appropriate error-correcting code and its parameter according to the demand of covert communication is a good outset for the research of information hiding based on error-correcting code. By applying the error-correcting code based information hiding technique to the field of digital authentication with the shared authentication key, a new research direction is achieved. And the technique can also be applied to the other communication field, which will bring a bright future to this technique.