> Lately, I've been leaving it on, but with an alternative OS
> (another Linux) whose sole purpose is to know if somebody's been mucking
> around.  My actual useful drive, data, passwords, go with me.

My keyboard also goes with me, which is the main inconvenience currently.

I think most common keyloggers require someone to pick up the payload in
person while you're out (with some magical password combination that gets
the keyboard to spew what it's been seeing).  If the keyboard's with me,
they will never get the chance.

Unless that sucker is broadcasting...  Which, ummm, I guess they all kind
of are in a SIGINT kind of way:

I'm sure there are fake/trojan keyboards that actively broadcast on
wifi/bluetooth without your knowledge.  RF detection/quieting can help
with that risk.

One of my current side-projects is a strongly encrypted keyboard.  Just
uses a PS/2 connector, but encrypts the channel with xxtea to a small
driver/xinput stub/decoder on the Linux side.  So even SIGINT style
monitoring wouldn't pick up anything useful.

(The sound/vibration methods of decoding typing can be mitigated a bit
with damping feet/neoprene base, and some other quieting techniques.)

A shorter-term personal project is to hack the existing keyboard's
controller to be socketed or on a daughter board.  Taking that with me
would be easier than the entire keyboard, and just leave some useless (and
stateless) contact switches and wire behind.  :)  Plus a clear (or
missing) top case to spot any other unauthorized changes.

I'm curious to some mentions-in-passing about Andrew's hate for USB
keyboards.  USB-anything isn't good for security, but what in particular
so much worse about USB?  Both USB and PS/2 can keylog, or play predefined
scripts to try and exploit the system.  One of the dangers of rogue USB
devices is that they can suddenly pretend to be a keyboard (which Linux
will accept without confirmation, something I'm not thrilled about).

But a keyboard is already a keyboard, it doesn't need to pretend.  :)

Is it that USB devices can spy on the whole bus?  (Is that true?  I think
I read it somewhere.)

(I do personally prefer PS/2, as it's simpler, less hackable, and
something I can more easily interface with for my own encrypted keyboard

Related, I don't think mouse tracking can be turned into anything useful
nor exploitable, as long as the mouse stays a mouse and doesn't go rogue
and suddenly show up as a keyboard and start typing an exploit.

And I'll digress one step further: it might be worth "hardening" the xfce4
GUI so that no dom0 window or menu can be fired up (by default) from the
keyboard.  That way, if a keyboard did go rogue in the GUI, and I don't
keep existing dom0 windows about, it can't open a dom0 window.

(I know, I know; if the keyboard/GUI is compromised, you can probably say
good-bye to dom0 and your computer overall, regardless.  Some a bit of
extra protection wouldn't hurt.)

Enough rambling.


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