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How to prove you know a secret without giving it away

quantamagazine.org

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141–150 of 171 posts

Re: How to prove you know a secret without giving it away

#141

Post by xrd »

There was a recent podcast by ZK Knowledge about homomorphic encryption and how this is different and complementary to ZK proofs. The founder of Zama had some surprising things to say (from my perspective) about how ZK is not something that can be used to guarantee privacy when used with blockchain tech. I'm sure that will be exciting news to everyone on HN. :)

https://zeroknowledge.fm/248-2/

Transcript, look for the timestamp with 28:55 to see that discussion:

https://assets.fireside.fm/file/fireside-images/podcasts/tra...

Re: How to prove you know a secret without giving it away

#142

Post by JanisErdmanis »

marcodiego wrote: post #140

Isn't it enough no show a hash?

It would be a random string for the verifier as he does not know the secret. It’s much like one can sign a document without revealing a secret key. In fact signatures are proofs of g^sk=pk where the document hash is a verifier challenge.

Re: How to prove you know a secret without giving it away

#143

Post by Tangurena2 »

vestrigi wrote: post #132
moffkalast wrote: post #107

According to school professors, the only way to prove that a person knows something is to lock them in a room for an hour or two and have them write down the entire thing on a piece of paper while being watched intently.

Well, most of the time I attempted a zero-knowledge proof in school I couldn’t convince the teacher ;) I think the difference is that the teacher already has the full knowledge and learning isn’t as easy as telling a secret once and then the learner can quickly parse it and keep it forever. Despite that, I’d also prefer to proof I know a topic by writing an essay at home rather than under pressure within an hour unde…

I was usually successful in proving to teachers that I had zero knowledge. :)

These were not the proofs they were looking for.

Re: How to prove you know a secret without giving it away

#144

Post by TheAceOfHearts »

alanbernstein wrote: post #60
yazzku wrote: post #8

Side topic, but why does something relatively respectable like Quanta Magazine need a reading progress bar? These odd decisions truly amaze me sometimes.

I’m glad it’s there. For decades, every long page had a progress bar. Then, nonsense design fads dictated that the scroll bar should become invisible on some browsers.

At least on macOS you can enable a setting to always show the scroll bar. And on Android Firefox it displays the scroll bar while actively scrolling so you know your relative position in the page.

Adding a progress bar seems redundant to me.

Re: How to prove you know a secret without giving it away

#145

Post by ozarker »

rcxdude wrote: post #129
DreamFlasher wrote: post #96

Earlier quoted context omitted.

Can you elaborate? Where can we find more about this game?

Sounds like a regular game of mafia or werewolves, which basically just requires someone to run it and some means of communication, whether it be in-person, IRC, forum, or some other chat application (there are more 'formal' versions of it in the form of board games or video games, like town of salem, as well).

Picked up Town of Salem recently. Quite a fun game. Have been pleasantly surprised with a good experience even with random other people most of the time

Re: How to prove you know a secret without giving it away

#146

Post by Double_a_92 »

ajsnigrutin wrote: post #110
moffkalast wrote: post #105

Earlier quoted context omitted.

That's just giving Waldo's coordinates with extra steps

If you don't know the books position under the foil, and the hole is just big enougn to show it's waldo, you cannot get the coordinates, but you know that the person who covered the book with a punctured foil knows where waldo is. People use the similar concept in geocaching when they forget to bring a pen... take a photo of a geocache against a neutral background (asphalt, grass,...) thus proving they found it, but…

But if you don't know the position of the foil, what does it prove? The other person could just move the foil around arbitrarily until it randomly fits.

Re: How to prove you know a secret without giving it away

#147

Post by Double_a_92 »

amenghra wrote: post #112
moffkalast wrote: post #109

Earlier quoted context omitted.

Well whoever's doing the verifying would need to have a way to align that piece of foil in a way that shows the position, and unless both people know that process it's useless anyway. If there's infinite possible alignments then you've given no data, but a piece of foil with a random hole in it. Like giving you two random numbers and you coming up with a function that maps them to waldo's position.

You might not have understood how this works. The prover shows the fact that they know Waldo's position by showing the page covered in foil to the verifier in person (or by taking a picture). The verifier does not manipulate anything. Obviously, there's no way to verify that the page under the foil is the page you think it is. This is more of an analogy / tool to explain things vs an actual secure protocol.

But then what is the point of the foil? Just take a very zoomed in photo of Waldo?

Re: How to prove you know a secret without giving it away

#148

Post by Double_a_92 »

bockchain wrote: post #38

> How to prove you know a secret without giving it away This is the best use case for blockchain. Put the secret on the blockchain and show others that transaction. Since it's on blockchain, no one can deny your claim about knowing the secret. This is why blockchain was invented. Before blockchain, I was miserable. There was no way for me to prove to my girlfriends that I knew a secret, without telling the secret. No…

Not sure if you are trolling? If the secret is on the blockchain, it literally becomes public by definition. And if it's encrypted somehow, what is the point of the blockchain?

You could just send an encrypted document to all the relevant people, and later on give them the key. At best the blockchain would prove that you actually send it to them (or everyone in that case), but nothing else.

Re: How to prove you know a secret without giving it away

#149

Post by Double_a_92 »

marcodiego wrote: post #140

Isn't it enough no show a hash?

A hash of what exactly though?

This would only work as a timestamp, if you ever plan to publicly release your secret.

But it wouldn't work if you e.g. want to find other people that also know what you know, without ever telling anyone. (Because they wouldn't have your exact text or document to hash...)

Re: How to prove you know a secret without giving it away

#150

Post by tptacek »

unnouinceput wrote: post #69
tptacek wrote: post #36

Earlier quoted context omitted.

It's pretty bad on the concepts, too. There are good books on the concepts that won't blow your head off; two of them are JP Aumasson's "Serious Cryptography" and David Wong's "Real World Cryptography".

Can you give an example of such a bad concept explained in Applied Cryptography vs Serious Cryptography? Because, out of curiosity, I just downloaded both books, skimmed on both of them (having read in the past Applied Cryptography it took me less time for it of course) through first chapters (classic crypto, randomness and RSA chapters) and found that they are very similar. So, again, do you have a proof of your sta…

https://sockpuppet.org/blog/2013/07/22/applied-practical-cry...

Even Schneier himself wouldn't make the claim you just did.

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