Using digital watermarks with image signatures to mitigate the threat of the copy attack

In some applications, the utility of an image watermarking system is greatly reduced if an attacker is able to extract a watermark from a marked image and re-embed it into an unmarked image. This threat is known as the copy attack. In this paper, we develop an image signature scheme to be used with digital watermarks to create an image watermarking system that is more resistant to this attack. We describe the image signature algorithm in detail, and how it may be fused with a digital watermark. We then present preliminary results of our system using an image test set of highly correlated images.