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Comment by doginasuit | Hacker News Reader

Zero-knowledge seems to be a bit of an oversell here. It is more like you break the knowledge up and only share the relevant parts with each party. And the facilitator (Google) arguably has access to the most information out of any of the parties involved.

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zero-knowledge proofs are a well-known tool in cryptography [1]. All Google is sharing is the library to implement it. Google would not have access to the information any more than they have access to the bank info of people who use Android or Gmail.

[1] https://en.wikipedia.org/wiki/Zero-knowledge_proof

It's my understanding that they are sharing the library but they will also be involved as a facilitator, at least to the extent that people use their identity wallet service. It also seems like they will have access to who you are sharing information with, which seems like the most valuable information for a company in their position, with nothing but a pinky promise that it will not be tracked. Let me know if any of that is inaccurate.

I don't know the technical details of this ZKP library, but there is no technical reason that I'm aware of that the ID provider would need to know who you are sharing with. Not to say Google didn't build it this way for business reasons.

Here is a good explainer of an ideal implementation of this (maybe). If its this, you would be incorrect.

https://blog.vrypan.net/2026/06/29/260629-whats-wrong-with-e...

You also can't know if Google has broken any of the ZKP promises, or in terms of the field, if Google is cheating and uncovered the secret bits you shared.

> any more than they have access to the bank info of people who use Android or Gmail.

...but they do? Google pay gives them your credit card and transaction details; any time your bank sends a statement to your gmail account, Google has that, too.

Am I missing your sarcasm?

Google has pioneered a few technologies where they are the trusted dealer. For example, Private State Tokens.

I have written a paper on how to do age verification in a completely privacy-preserving way, and it doesn’t even need zero-knowledge proofs:

https://magarshak.com/papers/Personal.pdf

How about not needing to do age verification?

Then I guess you'll be violating laws.

I'm talking about complying with laws, in a privacy-preserving way. It's possible.

Here, I posted it on HN: https://news.ycombinator.com/item?id=48760492

There are true ZKP setups where no one learns anything but the absolute minimum (e.g. is this person over 16, not what is their dob). This is hard to prove though and I don't know if I trust Google to do it

Ideally the government would be the issuer and the facilitator but the US lacks the state capacity to do this. Maybe it will work that way in Estonia.

The US is in the weird position of having a class of people (undocumented immigrants) who are often provisionally allowed to live there, known to their state in some capacity, and yet unable to receive some government documents that a permanent resident or citizen would be entitled to.

Europe doesn't really have that status. Either you're known to the government and can receive documents from it, or you're a criminal in hiding, avoiding any and all government offices.

No it's not like that in "europe". Plenty of people have been in the limbo state for years in portugal for example until the new government started expediting processes. I had several refugee friends which were in this situation and had local jobs and some forms of id but not others. Like having social security and a tax number but no official ID

I think that's been kind of solved by some states issuing IDs that don't make any claims about citizenship or immigration status. Then you could use that same ID online to prove age in our new dystopian future.

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