DMP is really Selective Device Jamming

Bruce Schneier looks at the innocuous-sounding "Digital Manners Policy" that Microsoft is attempting to patent:

According to its patent application, DMP-enabled devices would accept broadcast "orders" limiting capabilities. Cellphones could be remotely set to vibrate mode in restaurants and concert halls, and be turned off on airplanes and in hospitals. Cameras could be prohibited from taking pictures in locker rooms and museums, and recording equipment could be disabled in theaters. Professors finally could prevent students from texting one another during class.

The possibilities are endless, and very dangerous. Making this work involves building a nearly flawless hierarchical system of authority. That's a difficult security problem even in its simplest form. Distributing that system among a variety of different devices — computers, phones, PDAs, cameras, recorders — with different firmware and manufacturers, is even more difficult. Not to mention delegating different levels of authority to various agencies, enterprises, industries and individuals, and then enforcing the necessary safeguards.

Once we go down this path — giving one device authority over other devices — the security problems start piling up. Who has the authority to limit functionality of my devices, and how do they get that authority? What prevents them from abusing that power? Do I get the ability to override their limitations? In what circumstances, and how? Can they override my override?

It can be remarkably irritating to have some idiot's high-decibel custom ring go off at the theatre, or to be constantly interrupted by ignorami who can't turn off their Blackberries for half an hour during a meeting, but this proposed policy is overkill. Giving anyone the power to disable your cell phone would be troubling enough, and as Schneier points out in this article, the opportunities for abuse would be very tempting.

This, like over-enthusiastic copy protection schemes, should be fought as hard as possible.