🚀 go-pugleaf

In article <6568@skye.ed.ac.uk>, richard@aiai.ed.ac.uk (Richard Tobin) writes:
> It occurs to me that random-dot stereograms could be used for
> transmitting small amounts of information securely.  The recipient
> would be provided in advance with one half of the stereogram, and the
> other half would be constructed when needed.  

As the information in a random dot stereogram is stored in the disparities
between corresponding dots in the pair of images, isn't it necessary to
have the plain text in advance of constructing *both* images? This seems
to indicate that the `key' half is not in fact independent of the information 
to be securely transmitted and could therefore not be provided `in advance'.

--
graham

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