DRM vs. watermarking

You know, I've read and talked with people about digital watermarking before, but I haven't really thought about it as a means to deter piracy. But as I do so now, it's actually not such a bad idea. I don't know that we've come up with a mechanism resilient to fairly simple attacks, but if we did hae an ideal watermarking scheme, it might be a nice compromise for digital rights. The problem, as Butler Lampson has now famously stated, is not so much security (preventing people from copying) as it is accountability (knowing who copied what). If you can track down exactly who gave a copy of a movie to everyone, that's a big reason for them not to do it in the first place.

So, with watermarking, you would still be able to hold people accountable for illegal copying, but at the same time, you wouldn't need all the draconian, infuriating constraints that prevent people from doing obvious, perfectly legal things like copying a piece of music from one device to another.