Digital Watermarking

Protecting digital media data

The media security group of Fraunhofer SIT with numerous technologies for protecting digital media data. Digital watermarking being the main focus of the group.

Digital Watermarking embeds arbitrary information in digital media such as audio, video, images and ebooks. This is achieved through imperceptible, systematic changes to the media data. Security and confidentiality of the embedded data are thereby guaranteed by a secret key. Watermarks can be configured in such a way that they are robust against alterations of their carrier medium. Such changes could encompass (and are not limited to) format changes, analogue-digital-conversion, scaling or cropping.

The major advantage of watermarking is that a watermark medium is still a medium o the same type and that can do everything with a watermark medium that one could do with an unwatermarked one: They are still playable and copyable. Digital watermarking thus does not restrict usage - only abuse becomes detectable and traceable.

An incentive to stay honest 

With the Internet protection of copy rights and prevention of illegal distribution becomes ever more important. The holds true for detection manipulated or forged digital media. Digital watermarking can be used for example be used to protect copyrights by embedding information about the author or copyright holder into the medium. Images can thus carry hidden information about the photographer or the photo agency. But also every single copy of the same music file can be watermarked to distinguish and trace individual users. This traceability is what protects from illegal distribution and gives users an incentive to stay honest.

Tracing manipulations 

Significant changes to a medium can destroy or damage an embedded watermarks. Integrity watermarks use this property to detect (unwanted) changes to a medium. They have been developed in such a way that they survive allowed changes (like format conversions) and still can signal manipulations of the medium's content.

Broad media security competence

Multimedia security can only be guaranteed with a holistic security concept. Therefore our security competence pairs digital watermarking with supporting IT-security-technologies like encryption, digital signatures and DRM standards.