Security Matters: I've Seen the Future, and It Has a Kill Switch

"It's comparatively easy to make this work in closed specialized systems -- OnStar, airplane avionics, military hardware -- but much more difficult in open-ended systems. If you think Microsoft's vision could possibly be securely designed, all you have to do is look at the dismal effectiveness of the various copy-protection and digital-rights-management systems we've seen over the years. That's a similar capabilities-enforcement mechanism, albeit simpler than these more general systems."