Thursday, June 05, 2008

Digital Watermarking Questions

Ars Technica brought the interesting issue of digital watermarks to our attention via their news desk report on 30th May. Watermarks are increasingly being seen as an alternative to DRM and can be used to track copyrighted content purchased from legal download services. The US think tank, the Center for Democracy and Technology, has published a report making recommendations for the protection of privacy when using digital watermarks.

The report identifies two different types of watermarks; "generic" watermarks are the same to all versions of a particular file and "individualised" watermarks are embedded within copyrighted content to individual infringement and abuse. The use of individual watermarks is being used to track legal purchases of copyrighted movie and music files and enable copyright holders to trace the copies back to particular users or distributors, and potentially to launch legal action. The report recommends that individual watermarks use unintelligent numbers that can be match via a secure database to an individual and that no personal information is held within the watermark.

The article rightly points out that although it may reduce infringement watermarks would not protect the content from illicit file sharing. They go on to state that ‘even if a watermark is found on a peer-to-peer network and can be proven to be genuine, that isn't sufficient to prove that the person identified by the watermark is guilty of copyright infringement.’ There main issue is the use of individual watermarks and the potential loopholes and privacy issues.

The question of whether the individual can themselves secure the file from abuse is an interesting one and raises the question of whether legitimate purchasers should be exposed.

We have long looked to watermarking as the way forward but this article raises issues that we would now think hard about as it is one thing to tag a file with a generic watermark that can be tracked and another to place a hidden personal trace on a file that a legitimate user may not be able to secure themselves.

1 comment:

Peter Cox said...

Great points. Watermarking may well be the “acceptable” face of DRM and is already used in other digital products – it barely adds to the unit cost to personalize each file – and it could be compared to the 21st century equivalent of a library plate. The key issue is – if you’re not going to use individually-identifiable data (e.g. DNA, social security no) then it loses much of its punch. Clearly, there are many privacy issues arising. Also, like DRM before it, it *will* be an inevitable target for hackers…

Incidentally, your podcast with us ( is one of the most listened-to we’ve yet done – hope you’ll return soon!