Statement Regarding the SDMI Challenge

The Secure Digital Music Initiative (SDMI) is developing a comprehensive system to prevent music piracy. Central to this system is watermarking, in which an inaudible message is hidden in music to provide copyright information to devices like MP3 players and recorders. Devices may then refuse to make copies of pieces of music, depending on the meaning of the watermark contained therein.

In September 2000, SDMI issued a public challenge to help them choose among four proposed watermarking technologies. During the three-week challenge, researchers could download samples of watermarked music, and were invited to attempt to remove the secret copyright watermarks.

During the challenge period, our team of researchers, from Princeton University and Rice University, successfully defeated all four of the watermarking challenges, by rendering the watermarks undetectable without significantly degrading the audio quality of the samples. Our success on these challenges was confirmed by SDMI's email server.

Our paper describing our findings regarding the four watermarking challenges has been accepted for publication in the Proceedings of the Fourth International Information Hiding Workshop. The Workshop will be held in Pittsburgh, April 25-27, 2001.

This statement, a Frequently Asked Questions document, our full paper (when it is released), and other related information can be found on the Web at

For more information, please contact Edward Felten at (609) 258-5906 or

Scott Craver, Patrick McGregor, Min Wu, Bede Liu
Dept. of Electrical Engineering, Princeton University

Adam Stubblefield, Ben Swartzlander, Dan S. Wallach
Dept. of Computer Science, Rice University

Edward W. Felten
Dept. of Computer Science, Princeton University