The presently claimed invention relates generally to digital watermarking and steganographic encoding. One claim recites a method of encoding a watermark in a digital signal. The method includes generating varying key bits; and encoding the varying watermark key bits in the digital signal as a watermark...http://www.google.ca/patents/US7945781?utm_source=gb-gplus-sharePatent US7945781 - Method and systems for inserting watermarks in digital signals
