On Tuesdays the USPTO issues new patents. Both of today's Spotlight Patents address various aspects of digital watermarking. Assigned to digimarc, the first patent concerns layered security in digital watermarking. Assigned to Apple, the second patent concerns the use of watermarking in copy protection.
A media object authentication system uses layers of security features based on digital watermarks embedded in media objects. The system generates a first digital watermark with a message payload carrying data about the object, such as a hash of text data printed on the object. The first digital watermark is combined with a content signature derived from features of the media object, such as frequency domain attributes, edge attributes, or other filtered version of the media signal (e.g., image photo on a secure document) on the media object. This combination forms a new digital watermark signal that is embedded in the host media object. To verify the object, the digital watermark payload is extracted and compared with the data about the object. The combined digital watermark and content signature is also evaluated to authenticate the media signal on the media object.
7,519,180 "Method and apparatus for copy protection," assigned to Apple.
Copy protection techniques that utilize a watermark and a permission key are disclosed. The copy protection techniques can provide single-copy copy protection in addition to different levels of copy protection. The permission key and the watermark can also permit the invention to yield variable levels of copy protection. In one embodiment, content including a watermark is transmitted to a recipient. The recipient is allowed to read the content but not record the content unless the recipient possesses a permission key.