[110728] in cryptography@c2.net mail archive
Re: Intercepting Microsoft wireless keyboard communications
daemon@ATHENA.MIT.EDU (Peter Gutmann)
Fri Dec 14 11:02:31 2007
From: pgut001@cs.auckland.ac.nz (Peter Gutmann)
To: jamesd@echeque.com, smb@cs.columbia.edu
Cc: cryptography@metzdowd.com, ifarquha@cisco.com,
leichter_jerrold@emc.com
In-Reply-To: <475F2517.20605@echeque.com>
Date: Fri, 14 Dec 2007 18:52:11 +1300
"James A. Donald" <jamesd@echeque.com> writes:
>At every block boundary, keyboard transmits a special signal in the clear
>that signifies block boundary. Any time that no key has been pressed for a
>while, then when a key is finally pressed, keyboard transmits a bunch of no-
>ops sufficient to ensure that the recipient has recently received an entire
>block, followed by a complete description of current keyboard state, so that
... the battery runs down in a fraction of the time that it does for any other
keyboard on the market.
Would it be possible to use load modulation (e.g. ISO 14443, for which
transponders are readily available) to get around this, where the power for
the communication is supplied by the PC? That way you could have a protocol
that's as chatty as you like without your keyboard ending up as an advertising
device to make your competitors' products look good.
Peter.
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