Complementing DRM with digital watermarking: mark, search, retrieve

The purpose of this paper is to show how digital watermarking can be applied to assist and improve cryptography‐based digital rights management (DRM) systems by allowing the protection of content beyond the domain protected by the DRM system.

Digital watermarking is a passive technology, not allowing the active prevention of copyright violations. But it allows the irreversible linking of information with multimedia data, ensuring that an embedded watermark can be retrieved even after analogue copies. Therefore watermarking can be used where DRM fails: whenever content needs to be moved out of the protected DRM domain, e.g. when playing back content via analogue output channels it can mark the content with information that would help to identify its origin if it is used for copyright violations. The remaining challenge now is to find the marked content within the channels regularly used for copyright violations. The paper therefore introduces a concept for scanning file sharing networks for marked content.

The vast number of files present in the file sharing networks prohibits every approach based on completely scanning and analysing each file. Therefore concepts for filtered search queries where only potentially watermarked files are downloaded are discussed.

The paper shows how watermarking can be applied as a technology to allow active content protection beyond the limitations of current DRM systems.