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Humorous, but not zero-knowledge at all. They could be on to something here though. Maybe blockchain's "killer app" will be Verifiable Romance?
Last year my wife and I suspected we might have gotten each other the same Christmas gift, but didn’t want to spoil the surprise in case we didn’t. So we compared SHA256 hashes... and sure enough they both came out cb17007d (theragun)
This explained zero knowledge so much easier than that parable about the caves, thank you.
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Yeah I'm not sure what's the best protocol that's actually zero-knowledge here, but since we both trusted each other to only want to find out whether or not our gifts were the same, and otherwise to not spoil the surprise, this did the job.
You could write a script that does the hash comparison for you and simply outputs “Yes” or “No” for whether the hashes are identical.
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Doesn't work, because you can reasonably brute-force possible gifts.
You could reveal the hash letter-by-letter and stop as soon as a letter differs so there's more possibilities.
Oops - you just exposed a timing attack side channel
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This explained zero knowledge so much easier than that parable about the caves, thank you.
But it isn't zero-knowledge. If it was zero-knowledge, you would be able to know what you had the same gift/crush, but it would be impossible to prove to someone else. Mere hashing doesn't do that. For the crush example (This site), your crush could show everyone the link and their name. For that matter, someone could enter the names of everyone you knew in turn, until you were outed.
Earlier quoted context omitted.
This explained zero knowledge so much easier than that parable about the caves, thank you.
My favorite analogy is someone has a Wheres Waldo photo. They can prove to you they know where Waldo is by getting a piece of paper (the size of the photo) with a cut out around Waldo. When they hold it up and show you Waldo through the cutout you have zero knowledge about his location.
I think for this to work, the piece of paper with the cutout must be much larger than the full waldo photo. The actual cutout would always be in the center of this mask paper. Then the waldo photo can be moved around behind this mask.
Last year my wife and I suspected we might have gotten each other the same Christmas gift, but didn’t want to spoil the surprise in case we didn’t. So we compared SHA256 hashes... and sure enough they both came out cb17007d (theragun)