Note that this is an implementation of eIDAS:
The point of this is that you can use the credentials on your phone to prove that you are an adult to a website using zero-knowledge proofs to avoid disclosing your identity to anybody.
If somebody who has access to your unlocked phone can access the data in the app, then this is something that should be tightened up but it’s a substantial privacy improvement over the far more commonplace option of uploading your ID to every website that wants to know if you are an adult.
It’s an attempt to avoid things like this:
> Discord says 70k users may have had their government IDs leaked in breach (Oct 2025, 435 comments) - https://news.ycombinator.com/item?id=45521738
> The point of this is that you can use the credentials on your phone to prove that you are an adult to a website using zero-knowledge proofs to avoid disclosing your identity to anybody.
It is my understanding that this is not possible. I would be happy to be shown to be wrong, but to me it seems like you can either prevent people from lending out their credentials, or you can preserve the anonymity of the user, but not both.
You can use 0KP to prove you have a signed certificate issued by your government that says you are an adult, but then anyone with such a certificate can use it to masquerade as however many sock puppets they like and act as a proxy for people who aren't adults. You can have the issuing government in the loop signing one-time tokens to stop Adults-Georg from creating 10k 18+ attestations per day, but then the issuing government and the service providers have a timing side-channel they can use to correlate identities to service users. Is there some other scheme I'm missing that solves this dilemma?
> It is my understanding that this is not possible. I would be happy to be shown to be wrong, but to me it seems like you can either prevent people from lending out their credentials, or you can preserve the anonymity of the user, but not both.
This is not designed to prevent adults from coöperating with minors; that makes no sense as a design goal because any technical measure can always be bypassed with “download this for me and give me the file”. This is designed to prevent minors from being able to access systems without an adult.
Nothing prevents an adult from buying alcohol on behalf of minors; that doesn’t mean laws that prevent minors from directly buying alcohol are useless.
> You can use 0KP to prove you have a signed certificate issued by your government that says you are an adult, but then anyone with such a certificate can use it to masquerade as however many sock puppets they like and act as a proxy for people who aren't adults
The certificates in question can use a few mitigations: short lived, hardware stored (in a TPM, making distribution harder), be single use, have a random id which the service being accessed can check how many times has been used.
> but then the issuing government and the service providers have a timing side-channel they can use to correlate identities
That's not reallya concern, IMO. That would always exist as a risk - most people would probably have a flow of trying to do something, having to prove ID/age, doing that step, continuing with the something, which means you'd probably be able to time correlate the two sides quite often. The solution here is legal with strong barriers, not technical.
Can attestations be rate-limited or is that the timing side-channel you are talking about?
> The point of this is that you can use the credentials on your phone to prove that you are an adult to a website using zero-knowledge proofs to avoid disclosing your identity to anybody.
That's the theory. How is it in practice?
In my opinion, it just means there is a single government database to hack to get copies of all IDs...
By the way have the "security experts" checking this app evaluated that part? Or they're just worried about the app users cheating?
> In my opinion, it just means there is a single government database to hack to get copies of all IDs...
That doesn't make sense, all IDs are already in a single government database. Kind of by definition in fact, for IDs to be useful they need to be emitted by a central authority with associated security and revokability guarantees.
The implementations I've seen rely on an app reading your physical ID and its NFC chip, comparing that with a selfie to ensure it's the same person, and being able to provide anonymous proof you are of age based on that, or proof that you are indeed who you say you are.
> That doesn't make sense, all IDs are already in a single government database. Kind of by definition in fact, for IDs to be useful they need to be emitted by a central authority with associated security and revokability guarantees.
Yes and those databases are decently protected. However for an "app" someone will do a web 4.0 or 6.0 bridge to access these databases. Maybe even vibe code it. That's what I'm worried about.
Hence the second paragraph in my comment. The app is client side and reads the physical ID.
Hmm how is it zero knowledge when you can be tracked to a single installation of an app? I thought zero knowledge means they ask a "trusted" 3rd party, i.e. the government. And that says yes/no, without passing any ID details on.
You are mixing things up, and EU abbreviations do not help.
Many countries in EU already have electronic identity documents and delegate authentication to mobile apps one way or another.
eID or mobile identity application operating over QR codes and used to log into websites and apps is a commodity here.
This has nothing to do with age verification.
I’m not sure what you are saying I am mixing up.
The article links to the source code repository here:
https://github.com/eu-digital-identity-wallet/av-app-android...
That links to the tech spec:
> The solution leverages the existing eIDAS infrastructure, including eIDAS nodes and the trust framework for trusted services, to ensure a high level of security and reliability. By aligning with the technical architecture of the EU Digital Identity Wallet ARF, the solution delivers secure, reusable, and interoperable proofs of age.
> The solution enables users to present their Proof of Age attestation to Relying Parties, primarily for online use cases. The system is optimised for secure and privacy-preserving online presentation, allowing users to prove their eligibility without disclosing unnecessary personal information.
— https://github.com/eu-digital-identity-wallet/av-doc-technic...
Annex A includes details on the ZKP:
> AVI SHOULD support the generation of Zero-Knowledge Proofs using the solution detailed in: "Matteo Frigo and abhi shelat, Anonymous credentials from ECDSA, Cryptology ePrint Archive, Paper 2024/2010, 2024, available at https://eprint.iacr.org/2024/2010".
— https://github.com/eu-digital-identity-wallet/av-doc-technic...
And the linked paper:
> Anonymous digital credentials allow a user to prove possession of an attribute that has been asserted by an identity issuer without revealing any extra information about themselves. For example, a user who has received a digital passport credential can prove their “age is ” without revealing any other attributes such as their name or date of birth.
— https://eprint.iacr.org/2024/2010
> The point of this is that you can use the credentials on your phone to prove that you are an adult to a website using zero-knowledge proofs to avoid disclosing your identity to anybody.
No it isn't.
Literally that is not the scope document, and such a solution would not be permitted by the EU as compliant with the legislation.
The app isn't zero knowledge. A prototype workflow has been designed for a one way transfer to sites that is zero knowledge, but it doesn't actually deliver zero knowledge because it you have to verify your age with an external provider to get the credential (which is not zero knowledge), the app has to be secured with either Apple or Google's attestation services (which are not zero knowledge), and the site has to be able to check with the original external provider that the credential hasn't been revoked (which is in no way zero knowledge).
Zero knowledge proofs are when the prover can prove the statement is true to the verifier without disclosing more information beyond the statement. It doesn’t mean the prover cannot talk to other systems to produce the statement.
The alternative would be to just not do anything and to remove liability from Meta et al. In the world we live in, where competing interests already spent tens of billions to bribe/lobby the EU, we have to be realistic about it.
This open source and transparent ZKP-based approach is extremely surprising to see, publishing a draft in advance and inviting the public to break it so it can be improved? Are you kidding me? What about the billions of private investment in all the companies that offer centralized ID checks like Persona, Socure, ID.me and more? Thats a growing billion dollar industry. They all counted on this as a future market opportunity that the EU just seem to have destroyed at least in the EU?
People fighting against this age id app might be paradoxically useful idiots for billion dollar investments and lobbying efforts. The demos is once again dragged into the trenches to fight a war they don't understand.