chaos cryptography

[Sherry Mayo <scmayo@rschp2.anu.edu.au>]

Hi all - saw this in New Scientist and thought you might be interested
(I guess it's more stenography than cryptography):

==========
"Secret signals hidden in chaos

...John Hogan of the Engineering Mathematics department at Bristol
showed the BA how such unpredictable systems can be used to protect
sensitive information. His team mixed the information with chaotic
electrical signals, transmitted the result, and then extracted the
hidden message.

Hogan and his team modified simple electrical circuits to generate
unpredictable signals and hid within them a recording of "Land of 
Hope and Glory". When the two identical circuits are connected, said
Hogan, the outputs instantly synchronise so that anything added to 
the transmission stands out. "It's like magic." he said.

If anyone intercepted the signal and fed it through a loudspeaker
all they would hear is a loud hiss. This makes the system suitable for
hiding confidential information - once, that is, the system is perfected.
At present, a decoded message sounds like a scratchy 78 recording
although it is still recognisable, said Hogan.

So far the researchers have succeeded only when the two circuits are
connected by wire a few cm long. They are now trying to replicate
the results in circuits that are seperated by long distances and
connected by a radio link. They also want to see if it can be modified
for use with digital equipment."
============

Sherry

ps I wonder how close to real noise the "hiss" is.