The title of the Information Week column by Alexander Wolfe is both provocative and misleading. Microsoft has patented (U.S. Patent 7,266,697) “Stealthy audio watermarking”, which Mr Wolfe suggests could lead to “Uncrackable DRM“.
However even reading the patent’s abstract (“The watermark identifies the content producer, providing a signature that is embedded in the audio signal and cannot be removed. The watermark is designed to survive all typical kinds of processing and malicious attacks.”) that it would able that it might be, a best, difficult to remove the watermark. And it is significant that watermark survives audio re-recording (i.e. the analog hole). But that’s a far cry from “Uncrackable Watermarking”.
Mr Wolfe assumes a DRM (Digital rights management) system where the “playback system (i.e., the MP3 player or online music store) requires the presence of the watermark before it’ll let you listen to your file”. He seems to be thinking less of Watermarking than of Steganography.
(Leaving aside the questions why I would buy such a system, what happens to all the music I legally bought which is not watermarked, and not playable on such as system, and if he believes that the watermarks are irremovable why not allow the system to play files without any watermarks?)
That suggests that even if you cannot remove the watermark, you could still defeat the DRM by apply a applying a valid watermark to the file I was trying to get it to play, or getting the DRM system to accept a fake watermark signature as valid.
And that reduces, at best, to an issue of keys that need to be unencrypted before being used.
So it now looks a lot less theoretically uncrackable in the case of perfect implementation, let alone what might happen in the real world. Mr Wolfe recently admitted (Aug 1st 2007) that “When you look at the technology, there’s no getting around the fact that DRM is an abject failure“. He would like to suggest that you can now give Microsoft a “win” on this one. He might want to wait till the 16 year olds give it a crack.
That’s not to say the irremovable watermarking might not have real value, say in inserting each copy with the purchaser’s information. If the purchaser makes illegitimate copies, these will contain his name. Having my name, credit card number, email, telephone, and address will make me less likely to share my purchases (but what if someone stole my credit card and used it to by the latest Britney Spears single? The Horror, The shame!) That approach would only require a on line music store (iTunes?) to personally watermark the files when I buy them. That may not yet be practical, but is much more practical then anything else I’ve heard suggested. (patent pending).