Ambiguity attacks on the Ganic-Eskicioglu robust DWT-SVD image watermarking scheme

We consider the security of a DWT-SVD robust watermarking scheme for images due to Ganic and Eskicioglu. We show that although the scheme has been proven to be robust, it falls to ambiguity attacks, namely that both the image owner and an attacker can extract their watermarks from what appear to be originally watermarked images, causing an unresolveable dispute on the ownership claims of the image. The underlying problem is that the designers concentrated solely on robustness but overlooked the equally important issue of rightful ownership first defined by Graver et al. Without providing rightful ownership, a watermarking scheme cannot be used for proofs of ownership applications. To the best of our knowledge, these are first known attacks on this scheme