When the Secure Digital Music Initiative conducted its much-publicized SDMI Challenge — which offered a cash reward for anyone who could crack its protection — a group of Princeton researchers claimed they had found away around SDMI copy protection but refused to enter their solutions in the challenge because they preferred to publish them academically instead.
Now the SDMI is suing, and for now the researchers are backing down, to prevent the researchers from presenting their findings. Of course it’s a bit late since the paper that SDMI doesn’t want presented was already published on numerous web sites.
The interesting thing about SDMI is that, based on what the Princeton researchers found, the SDMI system was even less sophisticated than even its biggest critics had thought. SDMI utilize a watermarking scheme and the researchers used relatively straightforward methods to remove the watermarks without seriously degrading the quality of the sound (as they put it, the sound does degrade, but no worse than the degradation caused by the presence of the watermark itself).
In fact the methods the Princeton researchers are so obvious that quite a few Slashdot posters on the topic seem to think that the SDMI intentionally included techniques that it doesn’t plan to use and knows would be broken (though it is difficult to fathom why they would do this given that music companies were already a bit nervous about whether or not SDMI would actually provide copy protection that was reasonably difficult to circumvent).
As the Princeton researchers sum it up, all such copy protection schemes are likely doomed,
Do we believe we can defeat any audio protection scheme? Certainly, the technical details of any scheme will become known publicly through reverse engineering. Using the techniques we have presented here, we believe no public watermark-based scheme intended to thwart copying will succeed. Other techniques may or may not be strong against attacks. For example, the encryption used to protect consumer DVDs was easily defeated. Ultimately, if it is possible for a consumer to hear or see protected content, then it will be technically possible for the consumer to copy that content.