The Application Of Digital Watermarking In Electronic Credential

Abstract: This article has realized two kind of different electronic credential forgery-proof methods: space domain based fragile signature forgery-proof watermark method and transform domain based half fraigile signature forgery-proof watermark method. The key point of the method is how to detect the malicious modification and the watermark copy attack.These two kinds of methods first need to produce one kind of fingerprint used for distinguish, and the fingerprint is obtained from 128 bit disperse row value with the private key signature, which reflects the facial expression characteristic information and the documents information of the pass keeper. After carrying on 8×8 the piecemeal to the credential photograph face region and carrying on DCT on every block, the low frequency part of DCT value reflects the pass keeper facial expression characteristic information. Embedding the fingerprint and the pass keeper's documents information into the carrier image, it can obtain the forgery-proof watermark image. Making any revision to the pass keeper's photograph or documents information, it all can cause "the fingerprint" to have the remarkable change, which reflects the malicious interpolation. Because "the fingerprint" has reflected the connection of photograph and status documents, it could effectively prevent the aggressor withdrawing the information from the legitimate credential duplicating the information to the illegal photograph, which creates the copy attack..The two kinds of methods differ from the embedding method of the watermark. The former inserts directly the watermark into the RGB image least bit, which forms the airspace territory frail watermark image;But the latter inserts the watermark to the high frequency or the intermediate frequency strip of the image DCT block, which obtains the transformation territory half frail watermark after the DCT inverse transformation. Because the method of embedding is different, the two kinds of watermark characteristics are also different. The former is high sensitive to the attack, and cannot withstand any reasonable distortion (for example compression). The latter has reduces the sensitivity, but still could examine the evil intention attack, could withstand some reasonable distortions, might adjust its robustness through change in the quantification matrix of the DCT transformation.The experiment proves that it is one kind of effective credential forgery-proof technology, and can achieve the very good forgery-proof goal.