How to explain zero-knowledge protocols to your children (1998) [pdf]
pages.cs.wisc.edu
pages.cs.wisc.edu
Most importantly, I really liked the characters (just like I did in Snow Crash). It's interesting in that there doesn't seem to be an antagonist, really -- it's more about the journey of the young lady. It's a neat fairy tale.
Having said that, one of the messages I took from the story is that AI cannot replicate human to human contact.
He wanted, in fact, to show that it is possible to convince without revealing, and so without unveiling his secret.
Or from wikipedia [1]:
In cryptography, a zero-knowledge proof or zero-knowledge protocol is a method by which one party (the prover) can prove to another party (the verifier) that a given statement is true, without conveying any information apart from the fact that the statement is indeed true.
[1] http://en.wikipedia.org/wiki/Direct_Anonymous_Attestation