In principle it should be possible to do a zero-knowledge proof.

This means that the website asking for age verification asks a yes/no question like "Is this user 18+?" and the age verification service (like a digital ID provided by the government or whatever) answers "yes" or "no" accordingly, but without telling anything else about the user. Also, the verification service should ideally not know who asked for the age verification.

So the site you want to visit only knows the thing they need to know: Whether you are 18+ or not. Nothing else. And the age verification service only knows somebody asked for age verification and provided the answer, but do not know which site you visited.

This is all possible, but I don't have high hopes this is the intended implementation of any government seeking age verification, so don't get your hopes up.

The problem is not the system or the idea of age verification

The problem is that no one on earth can be trusted with that level of monitoring, control and power.

It can. Zero knowledge proofs have been around a while and are ideal for this.

They'll try not to have that because data gathering is what they're after, not keeping little Timmy from seeing some tits.

Even if it works, it’s a solution without a problem. If I can afford internet access, I am mature enough to see anything on the internet, and I am mature enough to decide which users can access my internet-connected network and whether they can have access to the whole internet. That’s all the age verification needed ever.

The request for age verification by each website is purely about unnecessary control and censorship.

No, It should be a browser setting. If parental controls are enabled, access should be denied to the site.

It is possible, but the real goal is about removing anonymity altogether

Yes. Look up "zero knowledge proofs"

It's possible with certificates and 2fa issued by a government, which already have all your data, that would only verify that you are over 18.

We already have that in Spain, sort of. We have a government app where you have a digital id stored and you can make it create a verify qr that only shows if the user is over 18 or under 18, no more data. The qr only last 5 minutes active.

It is necessary? Not for internet access. That's a duty of the one paying for internet in the household, not the government. If they have underage kids under their responsibility it's their duty to make sure that they get good education about what to see and what not and restrict access if needed. Having the government to universally interfere everyone it's just plain bad.

Its possible.

Open source front-interfacing app + a secure element thing in the backgound.

You download an app. You verify your identity, then the app sets up a OTP thing with the shared secret seed lasting for 30 days. But every 30 seconds the OTP changes. Everyone doing a verification in these 30 days gets the same exact secret seed.

The seed hides in the secure element of your device. (it won't be impossible to extract, but the average kid is not gonna be able hack a secure element) Every 30 seconds, it releases the new OTP to the Open source app. The app doesn't connect to the internet once the OTP has already been set up. So nobody knows if you actually view the OTP code.

So the government only knows you have the verification OTP set up not which websites you visited, the website only knows you have a valid OTP from the government, but you could be any of the people in the past 30 days (which the company don't even have access to).

Even if the company and government cooperates, they could only pin down the time of website registration and that you are one of the millions of people that did the verification and requested a OTP Seed.

(Idk the exact terminology for these things, but hopefully I make sense)

The government knows who you are. They know your age, your address and know you exist (probably).

You go to a site that requires ages verification. You say:please verify me with the government portal. You go to that portal to get a temporary id code to give to the site. The website says to the gov portal give me the name and age of the user with this temp ID. You approve that access. Portal sends age (or an is over 16/18/21 etc flag) to the site.

• Gov portal doesn't need to know who the site is.
• You don't provide a unique ID to the website, just a temporary one.
• as if codes are temporary, you must have access to the id/login now, not just at some point
• Site only gets the data you approve/it requested,.not everything.

The process can do with some streamlining, but should work in practice?

I'm inclined to say no. Reducing the problem down to its most basic parts: Alice is authorized to talk to Bob, but Bob doesn't know that. How can Alice prove it?

Bob has to assume that anyone asking to talk to him could be Mallory, who isn't authorized to talk to him but will always answer "yes" if asked whether she is. So the authorization he gets has to be from a trusted third party; it can't come from Alice.

Grace is a trusted third party. If Alice doesn't care about privacy, and is okay with Grace knowing that Alice talked to Bob and with Bob knowing Alice's identity, Alice can just tell Bob, "here's proof that I'm Alice. Show this to Grace and she'll confirm that I can be here." This is SSO, essentially.

If Alice doesn't want Bob to know who she is, but is ok with Grace knowing that Alice talked to Bob, she can ask Grace to give her a secret code, and give that code to Bob, who can check with Grace to know whether or not that code corresponds to someone who is authorized.

If Alice doesn't want Grace to know that she's talking to Bob, though, she runs into a problem. Because there's no way for Grace to send Bob a message without knowing who Bob is, he can't ask anonymously, and because there's no way for Grace to confirm that Alice is authorized without knowing who she is, Grace will always know that Alice has asked for authentication to talk to Bob.

Adding Dave in as a trusted fourth party could solve the problem—Alice asks Dave to check with Grace, and lock his answer in a bag with a unique key that only Dave has. Then Grace could give the bag to Bob, who doesn't need to know who Grace is to pass the bag to Dave and ask him to unlock it. But Alice would be trusting that Dave won't keep records on which bag corresponds to which person.

I don't think that's a surmountable problem. I'll have to think about it some more.

Correct, as a cryptography nerd I can assure you that you MUST at minimum have a trusted verifier which met you in person at some point (such as whatever office you get your physical ID card at) and they have to have your information.

And then you're trusting both Secure Element hardware and fancy cryptography where both must be flawless in order to protect the end user's side of it, all while the end user now carries much more personal information with them than before

Yes. There are many solutions.

Maybe the absolutely easiest to implement is just a signed message from an authority (gov.). You click a button on the website that requires verification, get a new tab to a gov. site with no identifiers from the site redirecting you and get a message you copy. The copied message is then pasted in to the site requiring verification. The site can then verify the message at their servers.

Nope, you always need a middle man to do the verification. That middle man has too much information.

Also, if you could solve for the middle man, there is no way to know the user belongs to the ID. It can easily be stolen.

I'd say it's impossible. Minors will ALWAYS find a way around it, even if it involves government IDs. The actual trick is finding if a "are you 18?" box is enough or not.

It's only possible as long as you trust the people you're giving your information to. So...no.

It is doable, i think. Consider:

You go to your local library. They verify you're above the age limit (like they do at supermarkets when you try to buy alcohol: either look you in the face and recognize you're clearly old enough, or have to show them some kind of id, details vary.)

You pick a code (put your hand in a box and draw a piece of paper at random). Nobody knows what code you picked except you. If lots of people do this at the same time, it's impossible to accurately map codes to people's identity.

You scan the code (like QR code) with your social media app that you use, and it associates the code with your account. Now everybody knows you have a valid code associated to your account, but nobody knows your identity.

(The code could work something like a cryptographic signature, where you can show that you have a valid code without actually revealing the code, so others can't simply copy it. That's a technical detail that you need to leave to the programmers to accurately understand.)

Depends on how reliable you need this system to be. For example, do you need to handle the scenario where an adult verifies their age to access a website, then lets a minor use that website in their place? That would be a much harder problem to solve than if you just need to verify that an adult was present on the other end at one point in time. For the latter, device-based age verification seems to be trivial to set up from a technical standpoint while fulfilling that criterion.

Yes, it is, see quark ID as an example of decentralized open source project by the city of Buenos Aires, in Argentina, which leverages zero knowledge proofs:

https://quarkid.org/
https://github.com/ssi-quarkid

It's possible but it would defeat the purpose of age verification

Yes, but your government doesn't want that.

Zero-knowledge proof. Medium has a practical example, though unfortunately the article logs user data, so beware on that.

There are tonnes of ways but honestly, the easiest way is to do it at the ISP level. Have an internet connection you don't want used for adult material? Have an opt in service at the ISP to block XXX rated sites and maybe social media. If you are old enough to pay for your own internet you should not be required to jump through hoops to access what you want, but kids should not be thrown onto the internet without guardrails. Some kids will get around it but it would be an active choice, so most kids would not. And to be clear, this would be done at the ISP level where you already have verification of age built in to billing, so no additional privacy concern. Honestly, the fact that this is not the solution is what tells me all of this filtering is not about protecting kids, it is about centralisation and control along with pork barrelling for age verification companies.

There are no registration or registry with individuals' information if guardians use parental controls and adult sites and apps identify themselves as adult for those controls, check what their kids are doing online, and talk with them about dangerous people or content they might see to teach them how to stay safe.

We could go by width of feet... You take a foot picture, it goes to another user temporarily while they sign in. If they think that's an adult then you're in. Then they take a foot photo and the next random user sees their image and they have to judge if the image is an adult. But the image could also be a fake. If they identify a false positive they have to wait 5 minutes. And so on. If others need to login they could judge the same image already identified as adult. If they think its not an adult then that user's logins is set to wait 5 minutes while two other users are snown the image. If those two users think its an adult then the user who said it was not an adult get to wait for 15 minutes. If however those two guys agree with it not being adult then that user gets permanently banned.

1. Sign up for age verification platform and upload your government ID on the platform (let's call this platform Age Verifier).
2. Age Verifier confirms you're an adult, and lists you as an adult in their system.
3. Age Verifier purges your government ID and any PII on you. The only thing they keep is your basic account details and the fact that they've confirmed you're an adult.
4. The next time you login to an adult site, you verify yourself by logging into Age Verifier's platform. The adult site confirms with Age Verifier that you're an adult, and you're good to go.

This system probably works, but it's not without its downsides. We'll need a way to confirm that your government ID and PII is actually deleted on Age Verifier's platform. A way to deal with this might be to make sure Age Verifier is never driven by profit so they'll never need to look into selling people's data. Maybe it could be ran by a non-profit? Or perhaps it can be ran by the government? But if you don't trust the government, that could be an issue.

And I can also see an issue where one guy who keeps creating different Age Verifier accounts, verifying that the account is an adult, and then selling that account to people.