aural cryptography

[David Honig]

At 11:50 AM 4/8/03 -0400, John Kelsey wrote:
>Guys,
>
>I was re-reading the original visual cryptography paper last night, and had 
>an odd thought: Why couldn't we do something similar with sounds?  The 
>human ear/brain is pretty good at pulling patterns out of noise; would it 
>be possible to randomly embed half of a low-quality voice channel in each 
>of two sound channels, so that they didn't sound obviously bad apart, but 
>when played at the same time, would allow the listener to hear a spoken 
>message pretty clearly?
>
>It seems like you could even do some pretty weird things with this, like 
>embedding the signal in four or five sound channels, or embedding them in 
>such a way that the speakers on the different channels had to be a certain 
>distance apart for the embedding to work.
>
>So my questions are:
>
>a.  Is this really possible?  Or am I missing something?
>
>b.  Has this been done in the open literature?  (It seems like the sort of 
>thing that would have been really useful for, say, radio broadcasts that 
>were intended to be received by spies.)
>

You could put nominally subthreshold speech in each of two
aural channels and let the brain sum them.  But in practice,
no.  First, individual thresholds vary.  Second, voice
is not a constant-amplitude signal.  

Also of course, as with visual perception, 
a machine can do this.  Indeed, for audio, 
spurious nonlinear artifacts might do it
unintentionally.





---------------------------------------------------------------------
The Cryptography Mailing List
Unsubscribe by sending "unsubscribe cryptography" to majordomo at wasabisystems.com