I don't understand how a technical audience like HN wouldn't be interested in stuff like this. Sure, maybe it's all exotic solutions to fake problems. They're s

I don't understand how a technical audience like HN wouldn't be interested in stuff like this. Sure, maybe it's all exotic solutions to fake problems. They're still pretty cool solutions! ZK-tech allows you to prove that you evaluated `f(x)` and got `y`. Normally someone would have to evaluate `f(x)` themselves to verify that `y` is the output, but if you encode `f` as a ZK circuit, in addition to getting the output you also get a succinct proof that you evaluated `f` correctly, In other words, you get `f' : x → (y, proof)`. The proof can then be verified in constant time for SNARKs, or log-poly time for STARKs. And depending on how you construct the proof circuit, you don't even necessarily need to know `x` to verify the proof! How crazy is that? To me, this seems like cryptography from the future. It's not even something that would obviously be possible. It wasn't invented by cryptocurrency developers, but it's impossible to deny that cryptocurrencies have advanced the field dramatically. (Reducing the overhead of creating the proof, for example.) There are tons of applications for this, too. Imagine you wanted to have a registry of "known-humans", a list of public keys where each private key belonged to a unique person. Now, a user wants to log into your website, and you want to verify that they're on this list. It's not obvious how to do this in a privacy-preserving way, that is, how does the user prove they control a private key associated with a public key on the list, without revealing which one? With ZK-tech, it's easy. The user downloads the list, encrypts something with their public key, then decrypts it, and does this all in a ZK circuit that produces a cryptographic proof that the process was done properly with a key that's on the list. Then they send the proof to the website, which is able to verify it without knowing the secret inputs (the private key, or the which public key was selected). There are other ways of accomplishing this that don't use ZK-tech, this was just a simple example.