The paper discusses the challenges and vulnerabilities of copyright marking systems in digital media, particularly in audio and video. It highlights the need for robustness in these systems to withstand various attacks that could render the embedded marks unusable or removable. The authors describe several simple hiding methods and present attacks that can defeat them, such as jitter attacks and the mosaic attack. They also introduce StirMark, a tool designed to test the robustness of image marking algorithms by simulating common distortions like resampling and geometric transformations. The paper concludes by emphasizing the importance of recognizing marks after they have been embedded and subjected to distortion, suggesting that progress in this area may come from developing better recognition techniques.The paper discusses the challenges and vulnerabilities of copyright marking systems in digital media, particularly in audio and video. It highlights the need for robustness in these systems to withstand various attacks that could render the embedded marks unusable or removable. The authors describe several simple hiding methods and present attacks that can defeat them, such as jitter attacks and the mosaic attack. They also introduce StirMark, a tool designed to test the robustness of image marking algorithms by simulating common distortions like resampling and geometric transformations. The paper concludes by emphasizing the importance of recognizing marks after they have been embedded and subjected to distortion, suggesting that progress in this area may come from developing better recognition techniques.