Digital Watermarking

Abstract

There is one aspect of copy control that digital rights management technologies based on encryption do not address. It is the case when the high value content leaves the “digital world”, namely when it is converted to waveforms that can be heard or seen by people. To solve this problem, there has been a growing “interest” on digital watermarking, mainly created by pressure from the content industry on the consumer electronics and the high technologies industries to find ways to better protect copyrights. Watermarks are imperceptible marks hidden in multimedia object, including audio visual signals. In a typical content screening system, the client’s media player searches the content for such hidden information. If the secret mark is found, the player then verifies whether a valid license is present. By default, unmarked content is considered as unprotected and is played without any barriers. To be effective, the watermarking technology should be such that breaking a single player or a subset of players does not compromise the security of the entire system.