4 ms·

The network demonstration of knowledge of the secret passage by 40 coin flips appears unnecessarily complicated. Why not simply send Mick down the left path an

by tromp 4y ago

The network demonstration of knowledge of the secret passage by 40 coin flips appears unnecessarily complicated. Why not simply send Mick down the left path and show him returning from the right? That directly demonstrates Mick knows a passage from left to right (at least to all observers at the fork. home viewers still worry about video editing).

Khoth 4y ago
To be a proper zero knowledge proof, it mustn't prove to bystanders that Mick knows the secret. With your simple proposal, everyone watching is convinced. In the more complicated version, only the person calling left/right knows for sure. As far as everyone else knows, Mick doesn't actually know the secret and the reporter colluded with Mick to pre-arrange a sequence of left/right calls.
- true_repairman 4y ago
  Why should bystanders not know? It seems like Micks proof is an attempt at fame, so he would want everybody to know.
  - Khoth 4y ago
    Because it's an imperfect real-world analogy for something used in cryptography
    - SamBam 4y ago
      Yeah, I understand why the author wants to turn it into a probabilistic argument, but it doesn't quite work with the circular cave analogy. You need something where the entry and the exits are different, and Mick Ali were able to use his secret to affect the outcome at the exit. What if Mick Ali were going down one of those twisty waterslide tubes, and could say his secret phrase to shunt himself off to a different fork, so he could come out at a different tube exit at the bottom?
- tromp 4y ago
  > To be a proper zero knowledge proof, it mustn't prove to bystanders that Mick knows the secret. Citation needed.
  - vintermann 4y ago
    Try any cryptography textbook! This is the whole point of zero knowledge proofs: that you can convince someone, yet they have no evidence (i.e, "zero knowledge") that they can take to another person and expect to convince them.
    - tromp 4y ago
      No, the zero knowledge part is that they only learn that you know a secret, but they don't learn anything about the secret. It's not about convincing others.
      - vintermann 4y ago
        If you get some piece of evidence that you can take to others, then you do in fact learn something about the secret.
  - daveloyall 4y ago
    This is the second time I've read this Ali Baba paper and I'm pretty sure I got hung up on this, too. And I don't see what that property is good for (though I am aware that other people do). Maybe the paper should have a preface. It might work for entertaining someone who already knows all about zero knowledge proofs, but it doesn't seem to do much to educate those who do not.
ianmiers 4y ago
if you just sent Mick down the left path and he came out the right, then a video would conclusively show he knew the password. And this is why "How to explain zero-knowledge protocols to your children" is probably the worst way to explain zero-knowledge protocols to anyone. Its not explaining what a zero-knowledge proof is or how it works. It's explaining what a simulator is when proving a protocol is zero-knowledge . Oh, and the explanation only works for interactive protocols.

by tromp 4y ago

Khoth 4y ago

To be a proper zero knowledge proof, it mustn't prove to bystanders that Mick knows the secret. With your simple proposal, everyone watching is convinced. In the more complicated version, only the person calling left/right knows for sure. As far as everyone else knows, Mick doesn't actually know the secret and the reporter colluded with Mick to pre-arrange a sequence of left/right calls.

true_repairman 4y ago
Why should bystanders not know? It seems like Micks proof is an attempt at fame, so he would want everybody to know.
- Khoth 4y ago
  Because it's an imperfect real-world analogy for something used in cryptography
  - SamBam 4y ago
    Yeah, I understand why the author wants to turn it into a probabilistic argument, but it doesn't quite work with the circular cave analogy. You need something where the entry and the exits are different, and Mick Ali were able to use his secret to affect the outcome at the exit. What if Mick Ali were going down one of those twisty waterslide tubes, and could say his secret phrase to shunt himself off to a different fork, so he could come out at a different tube exit at the bottom?
tromp 4y ago
> To be a proper zero knowledge proof, it mustn't prove to bystanders that Mick knows the secret. Citation needed.
- vintermann 4y ago
  Try any cryptography textbook! This is the whole point of zero knowledge proofs: that you can convince someone, yet they have no evidence (i.e, "zero knowledge") that they can take to another person and expect to convince them.
  - tromp 4y ago
    No, the zero knowledge part is that they only learn that you know a secret, but they don't learn anything about the secret. It's not about convincing others.
    - vintermann 4y ago
      If you get some piece of evidence that you can take to others, then you do in fact learn something about the secret.
- daveloyall 4y ago
  This is the second time I've read this Ali Baba paper and I'm pretty sure I got hung up on this, too. And I don't see what that property is good for (though I am aware that other people do). Maybe the paper should have a preface. It might work for entertaining someone who already knows all about zero knowledge proofs, but it doesn't seem to do much to educate those who do not.

ianmiers 4y ago

if you just sent Mick down the left path and he came out the right, then a video would conclusively show he knew the password. And this is why "How to explain zero-knowledge protocols to your children" is probably the worst way to explain zero-knowledge protocols to anyone. Its not explaining what a zero-knowledge proof is or how it works. It's explaining what a simulator is when proving a protocol is zero-knowledge . Oh, and the explanation only works for interactive protocols.