Intercepting Microsoft wireless keyboard communications

[Steven M. Bellovin]

On Mon, 10 Dec 2007 08:20:44 +0800
"Ian Farquhar (ifarquha)" <ifarquha at cisco.com> wrote:

> Exactly what makes this problem so difficult eludes me, although one
> suspects that the savage profit margins on consumables like keyboards
> and mice might have something to do with it.
> 
It's moderately complex if you're trying to conserve bandwidth (which
translates to power) and preserve a datagram model.  The latter
constraint generally rules out stream ciphers; the former rules out
things like encrypting the keystroke plus seven random bytes with a
64-bit block cipher.  Power is also an issue if your cipher uses very
much CPU time or custom hardware.

I"m sure most readers of this list can propose *some* solution.  It's
instructive, though, to consider everything that needs to go into a
full system solution, including the ability to resynchronize cipher
states and the need to avoid confusing naive users if the cat happened
to fall asleep on the space bar while the CPU was turned off.

		--Steve Bellovin, http://www.cs.columbia.edu/~smb

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