How the hack SDMI challenge was run

Automated procedure detected failed attempts, so the survivors are..?

All of the responses to the Hack SDMI challenge still being considered are likely to have entirely removed the watermark, according to inside information received by The Register. That doesn't mean that all - or indeed any - of them succeeded in producing an unprotected music file of tolerable audio quality, but it confirms the two-stage nature of the judging process.

The challenge was mounted by the Secure Digital Music Initiative as a means of testing proposed SDMI technologies, and the results have been a matter of dispute since Salon claimed they had all been cracked, and SDMI responded with angry denials.

Our sources confirm the two stage nature of testing, and suggest that the first stage was to all intents and purposes over as soon as the challenge closed. Incoming mail messages for the challenge were checked for the presence of a binary media file, and if present this was run through automated watermark detectors. If traces of a watermark were detected, the file was thrown away and an automatic 'you've failed' message was sent to the entrant.

These messages seem to have contained a standard "watermark was not completely removed" verdict, and a numeric value that probably indicates percentage removed.

Entries where no watermark was detected were then passed on to testing stations where the hack attempts would be checked.

The final verdict on whether the hack was successful or not will lie with the "golden ears," who'll be listening to the hacked tracks to assess whether or not audio quality is acceptable. This however cuts both ways, apparently. According to an eye-wtiness account in Stereophile, SDMI testers are also listening to watermarked tracks in an attempt to hear the watermarks. One of the four candidate technologies has already been eliminated because it was too easy to detect, the site reveals.

It also reveals that the golden ears are having trouble figuring out whether they can hear watermarks or not - inevitably, if watermarking goes ahead, this is something that'll keep hi fi buffs in arguments for years... ®

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