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I addressed this in the post > In our example, knowledge can’t be directly revealed, because we don’t have an easy way to “serialize” and share human knowledge

I addressed this in the post > In our example, knowledge can’t be directly revealed, because we don’t have an easy way to “serialize” and share human knowledge, like having met your mother — just the loose approximations of verbal and visual language. You can't share experiential knowledge of knowing another human being. You can claim to have met someone, but human experience isn't easy to transmit like a traditional private key.

dghf 9y ago
But doesn't that render the term so broad as to be meaningless? If someone claiming to be a police officer wants to ask me some questions, and I ask to see some ID, and they provide it, by your terms that is a zero-knowledge proof, because they can't share the experiential knowledge of being a police officer.
- mhluongo 9y ago
  "Proof" and "zero-knowledge" certainly still have meaning in the situation you've described. If we actually needed to do zk proofs over concepts like that, we'd need defined ontologies and all sorts of logic to codify "the real world". My point is mostly that it can be a subjective thing between the prover and the verifier. The verifier simply needs to be convinced, without making it easier for a cheating provers or future cheating provers, and the prover needs to not help a cheating verifier.
TheNewAndy 9y ago
Consider what happens if I happen to have forgotten my mother's birthday. I meet the person who claims to know them, and I ask a 19 questions about my mother where I know the answer, but I also sneak in the question about when her birthday is. With this scheme I use the 19 questions to check that you know my mother (that is the 1-bit of information that we are trying to prove), but with the bonus question, I get to learn something new about my mother. This shows that the proof communicated more than just the 1-bit of information. A real zero knowledge proof means that a person who is listening in on the proof doesn't glean any information either - at the end of the exchange, the only thing that has been proved is the single bit of information, and it has only been proved to the verifier. If you want a realistic example of this, then the cave example given on wikipedia is good for this. Note that at the end of the proof, an outside observer wouldn't be able to repeat the proof, nor would they even know whether the prover and verifier were in cahoots and actually just acted out the proof using a pre-agreed set of "random" choices.

dghf 9y ago

But doesn't that render the term so broad as to be meaningless? If someone claiming to be a police officer wants to ask me some questions, and I ask to see some ID, and they provide it, by your terms that is a zero-knowledge proof, because they can't share the experiential knowledge of being a police officer.

mhluongo 9y ago
"Proof" and "zero-knowledge" certainly still have meaning in the situation you've described. If we actually needed to do zk proofs over concepts like that, we'd need defined ontologies and all sorts of logic to codify "the real world". My point is mostly that it can be a subjective thing between the prover and the verifier. The verifier simply needs to be convinced, without making it easier for a cheating provers or future cheating provers, and the prover needs to not help a cheating verifier.

TheNewAndy 9y ago

Consider what happens if I happen to have forgotten my mother's birthday. I meet the person who claims to know them, and I ask a 19 questions about my mother where I know the answer, but I also sneak in the question about when her birthday is. With this scheme I use the 19 questions to check that you know my mother (that is the 1-bit of information that we are trying to prove), but with the bonus question, I get to learn something new about my mother. This shows that the proof communicated more than just the 1-bit of information. A real zero knowledge proof means that a person who is listening in on the proof doesn't glean any information either - at the end of the exchange, the only thing that has been proved is the single bit of information, and it has only been proved to the verifier. If you want a realistic example of this, then the cave example given on wikipedia is good for this. Note that at the end of the proof, an outside observer wouldn't be able to repeat the proof, nor would they even know whether the prover and verifier were in cahoots and actually just acted out the proof using a pre-agreed set of "random" choices.