| 摘要 |
A visible first watermark and invisible second and third watermarks are embedded in digital media content, in order to protect the media content from piracy. The visible first watermark protects the media content during distribution and storage, while the invisible second and third watermarks are embedded in to identify an owner and displaying entity, respectively. The second and third watermark keys can be used to detect the associated watermarks for forensic purposes. The first, second and third watermark keys are symmetric keys. A distribution entity embeds the visible first watermark in the media content using the first watermark key and embeds an invisible second watermark in the media content using the second watermark key. The distribution entity transmits the media content with the embedded visible first watermark and invisible second watermark to a displaying entity, wherein the displaying entity removes the visible first watermark from the media content using the first watermark key and embeds the invisible third watermark in the media content using the third watermark key.
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