Thursday, March 03, 2005

Conveyed Messages in P2P Files

"Greetings, Pirate! This is Mitch Bainwol speaking. Your days of Long John Silvering on the music industry will soon be over. We're upon you!"

This message could come through your speakers if you are playing an "illegally" downloaded song from a p2p network. And if RIAA head Mitch Bainwol chooses to make use of technique to embed a hidden messages in files. According to New Scientist this form of steganography ("covered writing") makes uses of the pattern of harmonics in the musical composition:
By forcing a few of these harmonics to move in and out of phase with a chosen reference, they can be made to convey a digital message. These phase shifts are so small they are imperceptible to the ear. But a software decoder, which could be built into MP3 players or file-sharing applications, detects the phase shifts and turns them into speech.
The full patent, supported by the Air Force Research Laboratory, can be read here. It explains the connection of this invention with DRMs:
The present invention would allow copies of the data to be distributed as unscrambled information, but would contain the capability to identify the source of any copy. For example, a digital rights management system implementing the present invention would inform users as they download music that unauthorized copies are traceable to them and they are responsible for preventing further illegal distribution of the downloaded file.
This technique seems reminiscent of a scheme that is used in a French anti-piracy campaign. In that case, however, the messages were not hidden and included in deliberate spoofs. This seems to be aimed at genuine songs, which would make it useless for p2p applications to filter them out as spoofs (though I can imagine there is always a workaround). Troubling is that this would require consumer electronics to include decoders, so that the messages would be played if acquired through "illegal" channels. That means another mandate on technological design. On a brighter point, this may also give rise to new theories about subliminal messages: "Jack Valenti is dead. Jack Valenti is dead." No, he's not.


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