> I'm envisioning a USB fob, attached to a bracelet, that triggers logout when it's disconnected, so by raising your hands, you've logged out. This exists, it

> I'm envisioning a USB fob, attached to a bracelet, that triggers logout when it's disconnected, so by raising your hands, you've logged out. This exists, it is called pamusb[1] and it allows you to automatically log in and log out using a usb stick. It would be simple to add password as well. The problem is, if your machine is still powered on, they can patch into the PCI bus and dump your RAM using DMA[2]. Most disk encryption stores the master key in RAM, so if they can dump your RAM they can decrypt your harddrive. GAME OVER! You really want something that cuts power to your laptop so all state is lost. It's not hard to build such a thing: 1. Setup your laptop to use full disk encryption, 2. remove the battery from your laptop, 3. pull the power cord to "instantly log out". One could even attach a string from the power cord to the door so that the laptop loses power if the door is opened. Cold-boot attacks[3], where they remove your RAM before it loses state, could be a concern, but they would have to disassemble your laptop very very quickly (within 30 seconds, perhaps longer if they just threw the laptop into a tub of liquid nitrogen). A counter measure would be to epoxy your laptop together to prevent quick disassembly (or use a macbook air those things are impossible to take apart quickly and the RAM is soldered in place). It should be standard operating procedure to randomly overwrite all non-OS data stored RAM when a user logs out. Maybe someone with most experience in disk encryption can tell me which products do this. [1]: http://pamusb.org/ http://pamusb.org/ [2]: http://en.wikipedia.org/wiki/DMA_attack http://en.wikipedia.org/wiki/DMA_attack [3]: http://en.wikipedia.org/wiki/Cold_boot_attack http://en.wikipedia.org/wiki/Cold_boot_attack