In this paper, a fragile watermarking scheme proposed for authentication of biomedical images in the Z-transform domain is analysed. The studied scheme takes advantage of the zero locations in the Z-domain which are sensitive to any tampering made on a watermarked host image. However, we are able to refute the designers' claims by carrying out at least two attacks on the scheme. Our attacks are based on the ability to determine the embedded check-bits in the watermarked image and thereafter, exploit the locations of the check-bits to alter the watermarked image while still resulting in successful authentication in the end.
Proceedings of the 1st International Conference on Forensic Applications and Techniques in Telecommunications, Information, and Multimedia and Workshop (E-Forensics 2008), Adelaide, Australia, 21-23 January 2008