Ever taped a record or CD music track for a friend? It's illegal, but lots of people do it without a thought. After all, the record companies are hardly impoverished. Now you can do much more. Millions of people are exchanging music, in the form of files, over the internet.
In the face of this, the music industry is out to protect its "intellectual property" (generally, creative work ripped off from songwriters and musicians). One of its campaigns involves legal attacks on internet companies that enable the exchange of music. The other is the use of technical methods to prevent the copying of music.
One of the methods for protection is called "watermarking". Watermarks indicate if a music file has been "compressed" (reduced in size), a sign that it has been sent over the internet. There are "robust" watermarks (that survive compression) and "fragile" ones (that are destroyed if the file is compressed or otherwise changed).
By themselves, music with watermarks, either original or changed, can still be played. The other half of the scheme is that the music-playing devices will be designed with detection mechanisms that can search for watermarks, and not play the song if the watermark is damaged.
While this sounds complicated, a similar system is already built into DVD players, stopping you from buying a DVD in the US and playing it in Australia, for example.
It is possible for a technically astute music enthusiast to get around any watermarking system according to some researchers.
A team from Princeton and Rice universities and the Xerox Palo Alto Research Center in the US wrote a fascinating (highly) technical paper describing how it could be done, and concluded: "we believe no public watermark-based scheme to thwart copying will succeed."
The paper is similar in its approach and detail to a host of papers in the encryption field, a common feature of this area of academic research.
Edward Felten, who led the team, was due to give this paper to the International Information Hiding Workshop in Pittsburgh on April 25. Here the issue becomes interesting (and political).
The organisation which promotes watermarking technology is a consortium of music industry companies, the Secure Music Digital Initiative. Felten and his team examined the technologies in response to a public "HackSMDI" competition organised by SMDI.
Two weeks before the presentation of their findings Felten received a letter from the SMDI Foundation threatening that "any disclosure of information gained from participating in the Public Challenge would be outside the scope of activities permitted by the Agreement and could subject you and your research team to actions under the Digital Millennium Copyright Act (DMCA)".
The DMCA is a notorious piece of US legislation that makes it illegal to attempt to overcome this sort of anti-copying technology, no matter how weak. It is now being used to persecute any academic examination of the technical issues involved.
In a statement to workshop participants, Felton wrote, "We look forward to the day when we can present the results of our research to you".
Fortunately, someone has published a leaked draft of the paper, at <www.cryptome.org/sdmi-attack.htm>. The case has also become the subject of a widely-supported free speech campaign.
BY GREG HARRIS (gregharris_greenleft@hotmail.com)