The Secure Digital Music Initiative (SDMI) has threatened to sue a group of researchers who successfully cracked the copy-protection routines that may be used on DVDs, if they publish their methodologies.
The SDMI is the US group responsible for testing digital watermark techniques, the likes of which are used on DVDs to protect against copying.
On Friday a copy of the SDMI's "refrain from any public disclosure" request, on Recording Industry Association of America (RIAA) headed notepaper, appeared on Cryptome.org, a site notorious for publishing documents that are "prohibited by governments worldwide, in particular material on cryptology, dual-use technologies, national security and intelligence".
Last September, four digital watermarks were put forward by the SDMI as potential industry standards for DVD protection. But before their launch, the group held an open challenge to determine whether the watermarks would be vulnerable to attack, thereby making them pointless.
A $10,000 prize was up for grabs to anyone who broke any of the four watermark systems on trial. Part of the competition agreement was that the methodology for breaking the watermark would not be published should anyone be successful.
One group headed up by a computer science professor, Edward Felten, managed to break all four watermarking techniques, but was not acknowledged by the SDMI because the group did not sign the competition agreements which would have restricted it from publishing the cracking techniques.
The lawyer's letter posted on Cryptome challenges Felten's intention to publish "information concerning the technologies that were included in that challenge and certain methods you and your colleagues developed as part of your participation in the challenge".
As a result, the SDMI urged Felten "to reconsider" his intentions and to refrain from any public disclosure of confidential information derived from the challenge. Instead, the SDMI asked Felten to take part in a constructive dialogue on how "the academic aspects of his research can be shared without jeopardising the commercial interests of the owners of the various technologies".
One of the main reasons the SDMI has to get hot under the collar about this situation is that one of the watermarks tested and broken by Felten, the Verance watermark, is already in commercial use for DVD audio, a next generation of music recording on DVD.
Should the technique for breaking DVD audio watermarking become widely available, people would be able to copy DVDs just as easily as they copy CDs today.
The SDMI's letter can be read in full here.
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