[epall]

But, then you've got to keep track of this "private key" thing that's completely intangible to users. What happens when they switch machines? What about when they accidentally format their hard drive? I think having a physical USB dongle would really be the way to go. Plug it in wherever you are, swipe your finger to unlock it. You've got two-factor right there in a simple, easy package. Now all we need is an operating system and environment that would support such a device...