Review on attacks, problems, and weaknesses of digital watermarking and the pixel reallocation attack
Security and Watermarking of Multimedia Contents III
Watermark attacks are first categorized and explained with examples in this paper. We then propose a new image watermark attack called "Pixel Reallocation Attack". The proposed attack is a hybrid approach, which aims to decorrelate the embedded watermark with the original watermark. Since many watermarking detections are by correlating the testing image with the target watermark, it will not work once we decorrelate the embedded watermark. For example, the geometrical transformation attacks
... nchronize the correlation detector with the testing image leading to detection failure. However, by inserting a template or grid into the watermarked image can make inverse transformation possible and the watermark can be retrieved. If we apply transformations to every single pixel locally, independently and randomly, inverse transformation will not be possible and the attack will be successful since the embedded watermark is not correlated with the original watermark. Experiment shows that single technique approach needs a larger distortion to the image in order to attack the image successfully. We also tested our attack with commercial watermarking software. It cannot detect the watermark after we applied the proposed hybrid attack to the watermarked image. However, watermark designer has only limited knowledge about the predicted attacks and even less for the unforeseeable new attacks during the design. It is very difficult to ensure the watermark will survive under these unforeseeable attacks. This is especially true for those watermark applications like robust watermarking for copyrights protection or access control (e.g. SDMI), which requires highest robustness and is subjected to all kind of attacks in various conditions. In this paper, we study different types of attacks to digital watermarking, based on a generalized digital watermarking model, which fits to many common digital watermarking techniques. In Section 2, we describe the said digital watermarking model. Different types of attacks are classified in Section 3. Non-Intentional and Intentional attacks are discussed in detail in Section 4 and 5 respectively. We then propose a new watermark attack in section 6 to show that simple but efficient attack can be developed easily. Experimental results are shown in Section 7. We conclude in Section 8 and future directions are discussed.