| 摘要 |
To overcome a watermark security system (160) that is based on a limited set of possible watermark values, a collection (110) of authentic watermarked material is created, and a substitution system (100) provides material from this collection in lieu of the content material that the watermark verification system is intended to verify. In security systems that are designed to verify the existence of authentic watermarked material, without regard to the actual content of the material, this substitution scheme will be successful. In security systems that are designed to verify the existence of an entirety of a data set in order to authorize the presentation of select material from the data set, the substitution of authentic watermarked material for the non-selected material will also be successful. A dictionary (120) of expected watermarks for the data set is provided. When the security system (160) requests the watermarked segments of the selected material, the selected material is presented; when the security system requests watermarked segments of the non-selected material, the dictionary of expected watermarks is accessed, and the appropriate authentic watermarked material is presented from the stored collection.
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