This might have been suggested before, but I think it's novel enough to repeat:<p>You should be able to create two passwords for all devices. One, your password, would allow you to use the device normally, the other, your lastword, would start a silent erasure of the device. The device could even present a fake successful authentication, like dumping you to some fake desktop, while it erases your data.<p>While in this case it would not really benefit someone in situations like US border crossings who have almost no rights, I think it would be very effective at discouraging attempts to force people to divulge their passwords, as the person entering the lastword would effectively be informing the device that it was under attack. With something like this I would think that questioning people for their passwords would be pointless.