A system for creating non-repudiation (undeniable) watermarks, wherein a content provider uses outside distribution entities to distribute media content supplied by the content provider. Content watermarked by a distribution entity using this system is undeniably recognizable by the content provider as originating with that particular distribution entity. In other words, given N distribution entities, the content provider is able to tell which particular distribution entity watermarked the media content. The system does not allow any distribution entity to watermark media content so that would appear to have been watermarked by another distribution entity and the system does also not allow the content provider to watermark media content so that would appear to have been watermarked by a particular distribution entity. Consequently, this allows the content provider to place a high degree of trust in the identification of the distribution entity by means of the watermark.