Security analyses of the watermarking scheme based on redundant discrete wavelet transform and singular value decomposition

This study analyzes the recent image watermarking schemes based on redundant discrete wavelet transform (RDWT) and singular value decomposition (SVD), and shows that in fact they are insecure and cannot be used for protecting the rightful ownership. The RDWT-SVD watermarking directly embeds a grayscale watermark image of the same size with the host image into the singular value matrix of the RDWT-transformed host image, then produces the left and right orthogonal matrices as side information which is later used in the watermark extraction stage. The RDWT-SVD approach enjoys the advantage of the RDWT redundancy to achieve a high embedding capacity, and preserves the watermark imperceptibility by exploiting the SVD stability properties. It is claimed that RDWT-SVD watermarking is robust against several common image processing and geometrical attacks, yet a fundamental flaw in the RDWT-SVD scheme is found, which leads to severe the false positive issue. Three vulnerable attacks should be considered in the RDWT-SVD scheme: (1) An attacker can easily claim the owner watermarked image; (2) the owner has the ambiguity because of the wrong side information usage, and (3) the owner can extract the correct watermark from arbitrary image. Thus, it is important to highlight these attacks when implementing the RDWT-SVD watermarking scheme.