Edward Felten - The SDMI Challenge

The SDMI Challenge

As part of a contest in 2000, SDMI (Secure Digital Music Initiative) invited researchers and others to try to break the digital audio watermark technologies that they had devised. In a series of individual challenges, the participants were given a sample audio piece, with one of the watermarks embedded. If the participants sent back the sample with the watermark removed (and with less than an acceptable amount of signal loss, though this condition was not stated by SDMI), they would win that particular challenge.

Felten was an initial participant of the contest. He chose to opt out of confidentiality agreements that would have made his team eligible for the cash prize. Despite being given very little or no information about the watermarking technologies other than the audio samples and having only three weeks to work with them, Felten and his team managed to modify the files sufficiently that SDMI's automated judging system declared the watermark removed.

SDMI did not accept that Felten had successfully broken the watermark according to the rules of the contest, noting that there was a requirement for files to lose no sound quality. SDMI claimed that the automated judging result was inconclusive, as a submission which simply wiped all the sounds off the file would have successfully removed the watermark but would not meet the quality requirement.