> They become a traceable identity token

Not if you use a challenge-response protocol where the client returns a zero-knowledge proof of age, where the proof incorporates a random string sent by the website.

The traceable stuff is private information that the website never sees. If a minor is caught with it, then law enforcement has local access to the minor's hardware and can probably view the private data.

At that point, the private key can be put on a public revocation list. The zero-knowledge proof can include a proof that you're not on the revocation list. Once you've been revoked, you have to go through the hassle of setting this all up again, which might be enough incentive to keep it reasonably secure.

I know! What puzzles me is responses every such article gets even on HN - let's build some cool tech that 95% of the general population and 100% of politicians won't even understand not to mention agree to.

Yes, government want to end anonymity and that's clear to some. But governments enjoy on a pretty broad support for this and many people supporting this believe it's a real problem. Suggesting to leave it unsolved or solve it in a way they can't trust or understand is only going to alienate them, making the government job easier.

I think suggesting a simple, cheap and effective solution to this problem that has no impact on privacy is a way better way to counter that. I think local parental controls fits the bill.

That's why they are still appealing to sentiment rather than established research (which actively refutes the arguments they are making).

Precisely. The people in power would love nothing more than to stop “disinformation” (facts that cause social unrest).

> The parents job is to keep their kids out of trouble. Learning how to keep track of what their kids access shouldn't be difficult

Unfortunately it is, but we could fix that with only minimally invasive legislation. Right now you either whitelist which breaks half the internet on a recurring basis (things are constantly changing) or you blacklist which is swiss cheese. Either way you're relying on third parties.

I think it would be much better to legally mandate a certain minimum level of self classification for website operators along with a simple and extensible scheme for communicating such. It might also be useful to mandate that devices ship from the OEM with parental control software supporting that standard but honestly I doubt that's necessary - if their were a standardized and above all reliable signal available I think browsers and operating systems would rapidly adopt support for it.

The problem with this idea is that it assumes responsible parents, which are not a given. I agree with you completely - I don't want any kind of controls on the Internet - but we live in a world where we cannot actually rely on parents to fulfill what you would consider to be basic and reasonable expectations of parental duties.

> It's anonymous. The clerk or his POS system knows your name and age, but doesn't know your number. The vendor providing the tape doesn't know your number or your name.

Where does this 3rd party identity token provider come from?

For government-issued identity tokens, there are not separate parties. It's just the government, and they can choose to link whatever they want in their internal system if they decide it's in the interests of national security.

You're also forgetting that lottery tickets are tracked. This is how they can announce which store sold the winning ticket before anyone steps forward with it. It would be trivial to match a buyer to the ticket if they wanted to inspect the records. In the case of a government identity token service, there isn't even a separation of parties providing the records. They do it all and can have all the data.

> It's anonymous. The clerk or his POS system knows your name and age, but doesn't know your number.

What prevents a commercial "AI" security camera analysis firm from doing a decent job of linking footage of a store's customers to a likely subset of tokens, based on the knowledge of which tokens are sent to which store and how many tokens have been pulled off of the roll so far? Remember that you can design the token roll packaging so the easiest thing for a clerk to do is to pull off the rolls in the order in which they were shipped. Or -hell- you can design the token dispenser so that it phones home to the oracle that sent the roll to the store with the range of tokens in the roll when the roll is loaded into the dispenser (for "security purposes").

> It's the exact same process by which you buy lottery tickets in a world where they don't need to verify your identity when you redeem them.

I've seen many people buy lotto tickets. I've never seen anyone asked for ID. Perhaps the merchant is supposed to check for ID, but they don't. Relatedly:

> The clerk pulls a scratch-off ticket from the front of a ticket tape. The ticket contains a token identifier.

What prevents rolls of those tickets from falling off of a truck and either being handed out for free or at a substantial markup, no questions asked? [0]

In the real world, the system you propose absolutely will not function to the standards required by the people agitating for these systems. You can't "protect the children" if "children" can easily get their hands on anonymous access-granting tokens.

[0] The fact that this doesn't happen with lotto tickets often enough to be newsworthy is not a compelling counterexample. Stores make a decent amount of money selling those, and wouldn't want to get cut off from that revenue source by regularly "losing" shipments of tickets. What you propose doesn't make stores any money, so either you have to spend a bunch of money to induce them to carry the tokens [1], or you have to have harsh penalties for "losing" shipments of tokens. If you risk harsh penalties for choosing to sell the tokens, why even bother? Stores put up with the risk of selling booze because it's quite profitable... selling 5c or 0c tokens absolutely is not.

[1] Where does that money come from? From you and me, of course!

> It's the exact same process by which you buy lottery tickets in a world where they don't need to verify your identity when you redeem them.

I’ve sold lottery tickets, and you have to be legal age to both buy and redeem them, so I’m not sure that this analogy or hypothetical solution is comparable to lottery tickets, nor is it likely to be the panacea you think it is.

I don’t think that the nascent online age verification schemes are good for society in general, either, but that’s not really the point you were making in your comment, so I don’t assume that you believe they’re good or bad, but simply advocating for a more privacy-preserving implementation. Which is kind of the whole point of the argument against bad implementations, but those who mandate and implement the systems likely view uniquely identifying people as a boon, whereas you and I probably don’t, which is why I am not hopeful that your ticket system will be used, because it will be higher friction for more people than uploading scans of their IDs and/or their face.

The ticket system, if implemented, would be used by so few people that the folks who do could likely be re-identified by Bluetooth tracking beacons and facial recognition in the same stores which they bought the ID tickets you suggest, and so I think the number of people who would escape tracking by any such means to be so few as to be a rounding error.

Those folks who do pursue this privacy hobby/fetish are statistically likely to ultimately mess up on their opsec eventually on a long enough timeline, so it’s hard to even imagine a scenario in which it matters either way what individual privacy activists do or don’t do from the point of view of the panopticon designers or implementers. Those not identified to a desired confidence interval by the mass surveillance system will just be retargeted for more sophisticated surveillance measures.

Despite how we rage, we’re still just rats in a cage.

More and more, the privacy debate feels like a quixotic struggle against giants, when everyone already knows that those giants are actually windmills; the majority of society now lives on reclaimed lands which rely on those windmills’ continued existence, and so no one cares about privacy in the way that you or I might care, because they are incapable of perceiving windmills as giants, nor do they have the intellectual or philosophical or political beliefs which would allow them to even entertain such perceptions even for the purposes of discussion. The privacy debate is beyond their ken.

No, I'm meant me, using my 18+ ID to generate a bunch of tokens that can't be linked back to me, and then giving it to random < 18 year olds for the lulz.

There's two strong incentives - deanonymization for law enforcement is pretty useful so that's one. You want to make it easier to subpoena information about posters for various reasons, access to stores on different dates etc. Lots of reasons for that.

And you want to satisfy voters who are worried about children online or have heard scary things about anonymous criminals. You want to be seen to do something about those.

A distant third is that you want the system to be cheap and built up fast and relatively easy so voters don't complain about it.

All together this leads you to something like "any time a site needs to verify your age (based on this broad list of requirements) put in your government ID number / picture". The infrastructure already exists for that, banks need it, social media needs it, and the current president has agitated for it a few times now. If you're really aiming high you set up some digital ID attached to it that's easier for the users.

For who?

Okay - so you verify age and what else?

What combination of details can you validate on that is meaningfully privacy-preserving and couldn't result in wide-spread re-use of tokens?

Additionally - what would prevent some kids from getting a homeless man in the city to hand them his ID, get a facial scan, and everything else you can think of to generate a token and then pass that token around?

ZKP are a cryptography-nerd's joy but are are categorically unsuitable for the purpose of age verification. I stand by this without the slightest reservation.

Every government has been working on ways to identify and target individuals online since as long as the internet has existed. Governments are incentivized to continuously increase control. Why would you assume this is not yet another escalation towards their goal of being able to track and silence anyone who pushes back?