On Fri, 12 Jan 2001, John Young wrote:
>Wright also describes the use of supersensitive microphones
>to pick up the daily setting of rotors on cryptomachines of the
>time, in particular the Hagelins made by CryptoAG.
Hmmm. That sounds like a trick that could be brought up to
date. If you get two sensitive microphones in a room, you
should be able to do interferometry to get the exact locations
on a keyboard of keystrokes from the sound of someone typing.
I guess three would be better, but with some reasonable
assumptions about keys being coplanar or on a surface of known
curvature, two would do it. Interesting possibilities.
Bear
[A quick contemplation of the wavelength of the sounds in question
would put an end to that speculation I suspect. --Perry]
