They are useful from a mathematical point of view. (And explore the relationship between P and NP, for example.) Not sure if that counts as a 'real use' to you. See also https://en.wikipedia.org/wiki/PCP_theorem
At the moment, producing a zero knowledge proof has roughly a million-fold overhead compared to running a program directly. So there aren't many applications where that's acceptable. So I am very grateful that the blockchain people are more than happy to throw money at the math here. Very generous of them.
In principle, you can use ZKP for privacy preserving compliance work in real (ie traditional) finance.
> Eg Goldman Sachs could encode all their compliance rules in a program, and publish a proof that their books pass the check by that program, without revealing anything about their accounting.
> In a banking context, you could in theory also run your know-your-customer (KYC) rules against customer provided data, store the proof, and delete the original data. That way, you still have proof that your customers don't have ties to North Korea or Russia, but you can't be compelled by anyone to reveal the data later (nor accidentally leak that data, etc).
> Of course, for that latter application, you need a sharp lawyer to make sure that storing the proof instead of the original data is enough for your KYC obligations.
> If you want to go further, you could have your customers run the KYC rules locally, so that their data never leaves their premises.
> (For all these applications, you still have to have a mechanism that connects the real world to the inputs of the programs whose execution you are proving.
> So eg Goldman Sachs would still need an auditor that checks that the assets and obligations they have in their balance sheet actually exist, but the auditor does not otherwise need to make judgement calls or apply any rules.)
ZKPs have only become cheap and easy enough to do in the last few years, so of course Goldman Sachs doesn't use them yet. They'll be using them in a decade, for now look at startups. https://github.com/zk-passport/openpassport is one that is working today, worldcoin ID verification is another.
I carefully gave examples of where ZKP can be useful outside of blockchains.
> Like they don't use blockcrap for interbank settlements, asset tracking, notary, etc.
Yes. So far the only way to track real world assets on a blockchain is to have a trusted third party (or third parties) that connect whatever your blockchain says to the real world.
But if you have that trusted third party, you might as well have them run the database that keeps track of who owns what. No need for a blockchain.
ZKP is different in the sense that it's one of only a few things to come out of the 'crypto' world that has at least a _chance_ of being useful in the real world. One day. Perhaps.
(Cryptography in general is enormously useful. Have a look at HTTPS for one example. When I just say 'crypto' I mean specifically everything to do with the blockchain ecosystem. So far the only real applications of crypto / blockchains that I've seen are gambling (generously called 'speculation' or 'investment') and ransomware payments. Cryptocurrencies aren't even good for buying drugs on the black market so far.)
In any case, ZKP is still very immature. But we are very fortunate that the crypto-people are generously funding this area of essentially pure mathematics research.
This must be a mistake or misunderstanding, because "blockcrap" is hardly mentioned in contrast with examples like confirming someone is of age, meets certain insurance requirements or has certain financial status without revealing anything about them. No blockchain is needed in any of these examples.
Part of growing up means realizing that cryptocrap is cryptocrap.
> examples like confirming someone is of age
When where are the companies that do that? Can I replace my Washington driving license with a ZKP that I can show to police officers or to enter a pub?
There are really no practical examples of the actual usages. Just hand-waving. And moreover, all the examples you provided make no sense. They are far better achieved using classic asymmetric systems.
On the contrary, your sentiment reads less like wisdom and more like hardheadedness. I am glad there are plenty of others here who do not share such a narrow-minded sentiment.
The venn-diagram between cryptocurrency and ZKPs is not a circle, or really even close. They're a mathematical concept first and foremost, and thanks to crypto dumping tons of money into the scaling problem, now much more easily worked with in code across any application. So much for all cryptocrap being, well, cryptocrap!
Your example is terribly contrived. No, you won't replace your drivers license with a ZKP. But a service might validate that you're of age, or meet some other criteria, without you(or they) revealing actual information about yourself.
All of the examples I gave(none of which are my own, but from other commenters who are I'm sure happy to discuss further) require the context of established trust. "Classic asymmetric systems" have problems with this.
I think you both 1) didn't read the article 2) went into the comments assuming it's about cryptocurrency and brought your baggage on that subject with you. The article mentions them in an offhand way, ZKPs are independent of anything cryptocurrency related.
The general takeaway is that you can prove you know something without revealing what it is, or how you know!
If you can't think of the possibilities that unlocks beyond the examples others have already discussed(none of which were crypto related), that's a limitation on your end.
And you still have to do that with ZKPs. Otherwise, I can just "borrow" my buddy's license and get into a pub. Unless the ZKP will interface with a biometric authentication system and do something like facial recognition.
And even then, it hand-waves away the issues with revoked licenses. How do you do license revocation with ZKPs?
> I've created a simple demo program to illustrate the concept of a human passport, inspired by World ID. It uses a zero-knowledge virtual machine (zkVM) to verify certain properties of a password without actually seeing the password itself.
I'm not sure what you're referring to specifically.
If you're asking why we need zero-knowledge proofs (ZKP) in a human passport system:
Imagine you have 6 billion to give away, and all lives worldwide should get their fair share. How could you do this? Giving money to authorities like governments and trusting them?
In the context of 'alllivesmatter.world', I propose the DUKI system. Here's how it works:
- Each person has a human passport (they should never have more than one)
- They can directly claim this money on the blockchain using the DUKI system
- This ensures that each unique person gets their share only once at each period
To achieve this and prevent multiple claims per person without considering privacy, we could use national security IDs, but these IDs need to be genuine, assuming that every human gets and only gets one.
However, using these IDs directly would compromise privacy. So instead, we let authorities prove that using ZKP:
- A valid national ID was used in creating the passport
- Each national ID is used only once in the system
This way, we preserve privacy while still ensuring the integrity of the distribution process.
Other service that focus on real people could also utilize on this. It just like currently wallet as an entry to web3 world, with only one key difference: that wallet represents a unique human in the world.
Thank you for highlighting the complexities around multiple passports and identity. Let me clarify the vision for a "human passport" concept:
1. The "human passport" I'm envisioning differs from traditional passports. Perhaps we could reuse the name WorldID that Worldcoin is developing, which uses biometric data like iris codes to ensure uniqueness. This approach is already working to some degree. Ideally, I just wish that it became a standard, with more implementations and also keep the iris-data at the device level, leaving countries with no excuse to refuse adoption. The goal is to have a standardized, cross-verifiable iris data system, rather than relying on a single authority to guarantee against forgery.
2. The varying name spellings on your different passports wouldn't be relevant to this system. Names are too variable to be components of a unique ID for each human. Instead, I imagine using something more like a social security number, that authorities issuing passports guarantee you never used twice at the same period. The ID thing is just a quick way to locate your public passport. The uniqueness check doesn't depend on this ID. It can be derived using your own private data to access your "human passport" released in public, which is generated using zero-knowledge proofs, and preserving privacy.
Its uniqueness relies on authorities, also relies on some biometric data for example iris-data one-way features, etc., so even if you try to trick the system and create multiple IDs, you'd probably get caught.
3. This isn't just a vision - WorldID is already in use with millions of users. I just wish for wider adoption and for countries to have no excuse not to adapt it as a worldwide standard. The human passport vision isn't about pushing crypto tech; it's about considering how to make 'all lives matter worldwide' from another perspective.
Because you can enforce password policies without the password ever leaving the (untrusted) client in clear text. I.e. the server only sees the hash and still knows it's dealing with a strong PW.
