Cold Reboot Attacks on Disk Encryption

Naw, don't shut down.  Presumably the real solution is to every n minutes throw away crypto
keys and at the next attempt to access the encrypted data, require the passphrase be
re-entered.  (We assume that attackers can't or won't breach the case to suck things out in
less than n minutes.)  Then if you want to get fancy, you can also add accelerometers to the
list of things that trigger the crypto keys being flushed.

Nagging the user on a timer is somewhat annoying, of course, but should be practical if one
really has secret data (and if you segregate out the actually secret stuff from the everyday
stuff).  It might even be a feature to bug the user occasionally while they have secret data
open, to remind them of this fact -- sort of a modern equivalent to root's "#" prompt.