Most convincing argument against DRM

I've been against DRM for the reasons that many people probably are, mainly that it's not futureproof and I don't want to choose a closed format (for example all my music is in Vorbis format). But this article from Cory Doctorow (author of one of the best blogs I read regularly: Boing Boing) is an utterly convincing argument that it doesn't matter whether you're pro or anti DRM, it isn't a viable proposition in any case.

I've always held that anything you can play, you can copy. The author underscores this by pointing out that DRM has an intrinsic conceptual flaw: it hinges on encryption, which in order to work requires you to keep secret one or more of the following: (1) the encrypted content itself, (2) the encryption algorithm or (3) the encryption key. But in DRM systems like iTunes FairPlay the publisher must give you all 3: the encrypted music, algorithm and the key.

Most, if not all, of the DRM cracks I've seen (Hymn for iTunes, DeCSS for DVD) involve simply working out what the secret key must be, since it has to be in the system that's playing it (based on the computer's hardware signature for Hymn, embedded in the software of a DVD player for DeCSS).

There are a number of even better, non-technical, arguments against DRM in this well-written essay. Well worth a read.