| 摘要 |
Techniques are detailed for steganographically embedding auxiliary data (103 0) within electronic content (e.g., audio, video, still imagery, etc.) (1020) i n manners that are computationally simple, yet highly inconspicuous (1010). Th e embedded data can convey copyright or other ownership information, or may be used for device control purposes (e.g., preventing unauthorized reproduction ). A number of countermeasures against removal of the auxiliary data are contemplated, including keying use of the content to the presence of such data. The embedded data may be made dependent on the media encoded, e.g., by modifying the embedded data in accordance with characteristics from the medi a. Encryption can also advantageously be employed (1040). Playback devices may be equipped to track IDs from previously-accessed content, and enforce usage rules. Some embodiments employ multiple watermarks to advantage, e.g., a robust watermark is encoded prior to distribution and indicates the content is protected, and a second watermark is encoded by the playback device and serv es to uniquely link that content to that device. Some applications benefit from scrambling of content, in a manner that leaves certain information (e.g., fr om a header) unscrambled and freely accessible.
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