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Digital watermarking security considerations

In this paper, we review our past experience with security of copy control audio watermarks, particularly related to SDMI. We also classify and analyze attacks published in literature and propose a number of security enhancement techniques for copy control and other digital watermarking applications. One type of security measure is based on uncoordinated selection of hiding places between embedders and extractors, with statistical analysis of expected matches. This approach reduces the repeatability of attacks and opens up the possibility of system renewal.Other security measures are introduced, based on weak watermark detections, time diversity extraction, weight accumulation, soft decision decoding, and extraction expansion or focusing. Finally, we propose a number of methods to conceal watermark presence, location and properties using random embedding, extraction and reporting, and random host signal modification techniques design to counter differential analysis or scrambling attacks.