Is it completely impossible to do age verification without compromising privacy?
from sheridan@lemmy.world to nostupidquestions@lemmy.world on 26 Nov 21:54
https://lemmy.world/post/39358563
from sheridan@lemmy.world to nostupidquestions@lemmy.world on 26 Nov 21:54
https://lemmy.world/post/39358563
To be clear, I’m not advocating for online age verification. I’m very much against it in any form. I’m just curious from a technical standpoint if it’s possible somehow to construct an accurate age verification system that doesn’t compromise a user’s privacy? i.e., it doesn’t expose the person’s identity to anyone nor leaves behind a paper trail that can be traced to that person?
#nostupidquestions
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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)
But only one person needs to “hack” it on their device to publish the key, allowing everyone to use it without “hacking” their own device.
You can’t store a key on a device and keep it safe from the owner.
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 one who asked the verification service also shouldn’t know who the verification service is, imho.
I’m not sure that is feasible, because in order to trust the answer, I feel the asker must know and trust the one providing the answer. It sounds like you’re imagining a system with many different ID providers? What prevents me from creating my own provider that just answers “Yes”, even for people under 18? If the site asking does not know it is my fake ID service providing the answer, I’m not sure they can trust any answer.
But I won’t pretend to be an expert on this topic, so perhaps it is feasible somehow.
This is possible if there’s a central authority for that that everyone can agree to trust, like the government records directly. The issue is ensuring the rest of the chain remains anonymous so the only thing the authority gets is the request that an undisclosed service is verifying John Doe is 18+ and nothing else. And that’s not something many governments are going to want to allow with the increasingly alarming amount of authoritarian leadership.
Or the government sets up an age verification service that doesn’t store logs and only reports numbers in aggregate. The restricted site sends you and a unique id off to the government service, you verify there and it hands back the id & a yes/no token to the site.
The government already has nearly all the tools to make this happen. They already have id verification services to use & web front ends to copy. Just build the public API and insist restricted sites use it.
doesn’t this just raise the authentication requirements? like in the uk we got added checks for who was could work, and lots of deliveroo drivers shared the login + password of someone they knew who was verified.
I think it should be easy to identify when an account is being shared. For example if it's used from different ip addresses within a short amount of time
You could make it single-use tokens and rate limit individual users when they request too many tokens in a short time. Someone could still share their tokens with a friend, but it doesn’t scale to where thousands are verifying with some stranger’s id.
There are some pretty strong arguments that even zk proof is a flawed way of preserving privacy though, in a variety of ways. It prevents pseudonymity by enabling one-user-one-account, and it leaves users vulnerable to being coerced to reveal their full online activities by handing over cryptographic keys.
Got ready to read some bullshit,
Vitalik Buterin
nevermind. But damn, what a great read. I haven’t given much thought to on-chain ID in years and he lays it out pretty well. Still sounds like encrypted tokens are the way to go, but we all need to have multiple forms for it to protect anonymity.
If there’s one person who knows their applied zk proofs, it’s that guy.
Not monero or zcash devs?
Indeed, technologically it is absolutely possible in multiple ways.
But the tempting possibilities of doing more than that are just too great.
I worked in this field for 3 years, a lot of the core parts are written, but there are a few key pieces missing and no one has taken it to real production.
You can use a passport in pretty much any country and prove you’re over a certain age. Here is a demo: github.com/dog-18/dog18
The parts that are missing are primarily around making secure nullifiers, which prevents someone from reusing identities, but also without revealing any private information. We were pursuing research that allowed nullifier generation in MPC where none of the servers or the users knew the “salt” that their identity was hashed with, so no one could recover the original piece of unique data (like their passport number, even if a govt had a hunch about which passports signed up to a service) but it would also prevent them from signing up with multiple accounts. We got our funding cut pretty bad and management was a mess, so I left and that research I think was shut down. This really is the key part to actually make that viable in the real world though. It’s maybe a year worth of research and a year worth of production left to make that practical.
Does that mean the government sees all the sites I’ve visited?
No, that’s what I wrote as well. The identity service would not know what sites were visited or ideally not even how many sites were visited.
It’s possible but it would defeat the purpose of age verification
How?
Zero-knowledge proof. Medium has a practical example, though unfortunately the article logs user data, so beware on that.
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.
IMO this is the hardest part to ensure in a transparent manner.
The token needs to be time and device sensitive. Should be possible via a hash
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.
Nah you can totally trust me, I’m too lazy to do anything nefarious
Great! … the solution to our problems … let’s all trust edgemaster72
Oh, oh shit, this has backfired massively, I didn’t think anyone would go along with it, that’s way too much responsibility
<img alt="" src="https://media1.tenor.com/m/HR52ABHbawwAAAAC/dsad.gif">
This is precisely what the chosen one would say!
Wait until you have that power and you’re made offers that are hard to resist.
You definitely can do this with cryptography, it’s a really hard problem, but I worked in this space for a number of years, it’s possible.
Like I implied, the problem isn’t the HOW to do it.
The problem is in giving any one person, government, corporation or company this amount of power and control.
And because it’s so powerful, no one who had it would want to give up control by making it anonymous or in objectively protecting privacy for the user.
Right, I understand that perspective, but there is a way to do this with multi-party computation and some other cryptography where no one would have the actual power/be able to see the data/have control. The main issue is it’s expensive to run and no one would be incentivized to run it.
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.
The process can do with some streamlining, but should work in practice?
Ya you could definitely do this way too. There is a standard that google came up with called private state tokens that would allow you to do this in a pretty clean way, if you were cool with using your governments portal.
Essentially you would login to the govt portal, they would issue you some limited set of tokens (let’s say 5) that would expire after 30 days. You would go to an age restricted website and sign up and that would “burn” a token.
You could use ZK on top of this to make sure that the same email address or some other “nullifier” piece of information was used, to prevent an 18 yo kid from selling their tokens to 17 yos.
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:
quarkid.org
github.com/ssi-quarkid
It’s only possible as long as you trust the people you’re giving your information to. So…no.
Not true, there are ways to do this privately with cryptography
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.
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.
Internet access is like $1 in most countries (Sim card data).
I don’t know about you, but the tooth fairy gave me enough money to pay for internet access before my skull was old enough to finish growing adult teeth…
And you had the capacity to pay for internet access?
You fucking walk 20 meters from your doorstep to buy a soda and a gig of data, yeah
Sounds like you’re mature enough for porn then.
the 11 year old walks back to the store to buy an orange juice, a bottle of lotion, and 10 more gigs…after discovering 4k video
No, It should be a browser setting. If parental controls are enabled, access should be denied to the site.
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.
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.
This requires you to trust gov that they will not trace where the secret message is pasted.
How about
Middleman anonimizer, pornhub sends the message to a middleman, the middleman puts its own token on the request, sends that to the gov, the gov responds yes/no to the middleman on the authenticity of the message, the middleman forwards the response to pornhub. The gov doesn’t see pornhub, pornhub only gets the yes/no response, the middleman only sees the message with no ID and the response as well as the site.
Requires a separate middleman maintained by who the fuck knows. Pornhub keeps your IP, the gov keeps your name, the middleman only knows the number of visitors on pornhub.
If they can trace it, why would they need the code to do it? They know who you are already
Hey benign and honorable govt!
Please tell the website “kill-your-govt .net” that I am old enough to join the revolution!!!
Kthxbai
edit: if this was pasted in both directions AND we trust that there is no identifying information in either ‘secret’ message, might work. Normies will not like the ctrl-c/ctrl-v workflow though.
That still creates a chain that can be followed. If the site you’re trying to enter is ever compromised, there will be record of your government code and whatever tracking is used to verify that you have entered your code.
I would be happy if the government was not involved in my online activities at all but I guess that ship is about to sail.
See also: timing attacks
In my ideal world, it’s not an issue because parents don’t let kids under a certain age or demonstrated maturity level have computers in their room alone, and even better, they teach their kids how to not have problems with predators, porn, and the deluge of online weirdness and have open, honest talks about how some things are dangerous because they prey on you, some things are dangerous because they get you hooked on certain feelings, and some things are dangerous because they give you false impressions of the world and relationships.
We’re about as close to that world as interstellar exploration, I know. Imagine having parents who you don’t feel afraid to talk to about mature topics and personal matters.
And all that aside, why is it such a big deal that kids not see boobs but they can see violence and gore? Why is it magically okay for Timmy Neckbeard to watch strangle-fetish porn night and day as soon as he turns 18? Why do we scream about how porn is ruining kids minds but we’re not taking down the grifting “masculinity influencers” with as much zeal as we’re going after pornhub and other sites that are mostly just consenting adults doing fun biological acts together? Why do we say porn companies are evil and not do anything to make it less evil like better regulations and resources since we know people are going to find ways to make and view it anyway? (These aren’t questions for Lemmy but I would sure love to see communities start asking these questions to their elected representatives.)
Our species’ obsession with clear lines and labels is making us ignore where the actual problems are, we build fences around the outcomes not the sources. We create solutions to problems we don’t even want to look at directly. It’s like the government handing out umbrellas to combat the issue with the massive water main leak flooding the street.
That’s because their bunch of hypocrites. The only thing they’re fuelled by is misinformation and greed. Emotional manipulation is their go to weapon because their macharvellistic ego only lives by that.
Don’t get me started on discrimination which comes with this type of situation. Teens/adolescents being infantilised, and indoctrinated that they know fuck all then being lumped right in with children.
But why should they explore their sexuality if they can read the bible instead - to remain pure. Of course, touching your Coochie will land you strait to the devil himself.
At that point, the quote never have sex until you have married makes more and more sense. It is control from the first moment you become a teenager to the point where marriage becomes a thing. All because of this perceived purity (Even if the bible isn’t in its entirety pure).
If anyone is doing actual work trying to solve this please DM me, I’m interested in helping.
Yes. Look up “zero knowledge proofs”
I mean “no, look up zero knowledge proofs”
Yesn’t
Yes, but your government doesn’t want that.
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 figured you were wrong so I asked an AI and it confirmed what the people below you were saying, you really do seem to be talking straight out of your ass
Yes, it is technically possible to build an accurate, high-confidence age-verification system that does not compromise privacy in the traditional sense (i.e., no central database of IDs, no name/address/DOB stored by the site, no paper trail that can be subpoenaed or leaked). The core tool that makes this feasible is zero-knowledge proofs (ZKPs), specifically age-based ZK proofs.
How a privacy-preserving age check actually works in 2025
“I have a valid credential signed by [Trusted Issuer] that confirms I am 18+ (or 21+).”
Real-world implementations that already exist or are in late-stage pilots (November 2025):
Remaining practical hurdles (why it’s not universal yet)
Bottom line
Technically: Yes, 100% possible today with zero-knowledge age proofs.
Practically: It exists, works, and is slowly rolling out, but the porn industry and most social platforms still prefer cheap/frictionless (but privacy-invasive) methods or just do nothing.
So the top reply in your screenshot (“you always need a middle man with too much information”) is outdated — cryptography has already solved the “middle man” problem. The real blocker now is deployment inertia, not theory.
Read back what you wrote. Your first line was about a trusted credential provider. Thats a middle man. Then you talk about creating a proof. Guess what, that phone and browser are known to spy on you excessively. That’s another middle man. And odds are that same phone or browser it what you will use to access something that needs the verification. So the same phone or browser has all parts of the information.
And of course it’s pointless because anyone could steal an ID and get themselves a key. Or steal your phone… so it wouldn’t even prove anything.
I’ll address the second objection first regarding the phone or browser. You’re always going to rely on some technology for the solutions that use cryptography, you just can’t do those calculations long-hand realistically. That said, look up frameworks like CTAP that allow a potentially untrusted user terminal, like a browser, to interact with a trusted hardware token. Those hardware tokens can be made fairly tamper-proof, see FIPS authorized Yubikeys, such that the phone is pretty much removed from the attestation process. Yes these can still be stolen, but they make hardware keys that are fingerprint authenticated and the biometric stays on the device. Doesn’t get much more self-sovereign than that.
The existence of a trusted credential provider is a challenge. Fully self-sovereign credentials need to either be trust on first use or validated against a larger system everyone participates in. Even if we had some system of birth certificates tied to a distributed ledger, we would have to trust the third party recording that certificate in the first place, be it a hospital, doctor, or state entity. These trust and proof systems don’t create the trust, they just allow us to extend that trust from one claimant to a verifier. Whether you place that trust in the state, an individual, or an independent third party is up to you.
So, you have fully backed my response. OP didn’t ask if it was possible with some caveats. I understand a (at a high level) the technical options that can get close to what OP asked for, but it fundamentally just isn’t possible without caveats.
Just for your edification anything you say after “so I asked an AI” is going to be ignored by most people. It just tells me everything that comes next is not going to be worthwhile. Might as well tell me your palm reader told you something.
Ok
The big flaw in this strategy is that once you have set up a signed anonymous key from the government and you can make zero knowledge proofs with it, there’s nothing stopping you from distributing that key to every kid who wants it. If it’s in the browser or an app, etc. you can publish that signed key for anyone who wants to be over 18.
PKI only works if the owner of the private key wants it to be private. It’s effective for things like voting or authenticating because the owner of the key doesn’t want anyone else to be able to impersonate them. But if it’s only for age…
At that point, it might as well just be a file that says “I pinky promise that I’m over 18” that the government has signed and given to you.
Could tie it to something like a biometric. That and storing it on a write-only device would keep it from being shared too wide. The trickiss to tie it to a true multi-factor and not just something you have (if unencrypted) or something you know (if ASCII armored).
Then it adds barrier to entry. If it costs money it will be a problem for the more vulnerable population. If it is free and you can have as many as you want it is gonna be abused, if there is a limit it again starts to be a problem.
Pot, you are black! Signed, kettle
We could just make the middle man somebody who already needs that information, e.g. the IRS.
You could, but that wouldn’t address OPs question. The IRS is known for giving info to other parts of the government to aid in prosecution. And the gov has shown they are terrible at cyber security, so you might as well just post your browser history on the web.
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.
The users confirm others at random.
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.
Here’s my idea: Bob gives Alice a token, assigning her an unique random number n. Alice goes to Grace and tells her, “Somebody assigned me number n, can you verify that I’m allowed?” Grace then writes: “User n is allowed, signed Grace”. Alice then takes this letter and shows it to Bob. Bob now knows that Alice is allowed, but nothing else. Grace only knows that somebody wanted to know that Alice is allowed, not who that somebody is.
Of note here: This system does nothing to protect against an allowed user helping a not allowed user to gain access, but I don’t think it’s possible to protect against traitorous users.
There is no system in the world that can fully prevent an authorized user to grant access to an unauthorized user. Even with an all time on camera and screensharing I can still find ways to have someone else control my computer while I “authorize” the connection with my face in the camera
Yeah a small false-positive rate will have to be accepted. This is the same like you can’t fully prevent minors from getting access to alcohol. Consider that their older sibling can buy it for them (at an increased price, ofc).
What matters is to keep the rate of false positives reasonably small, i’d say.
This is called a nonce.
Which as a Brit is a really bad name for anything used to access porn.
We could change it to being called a Mountbatten-Windsor but that’s a much lengthier way to say the same thing.
That could very well work, yes; but I think that would require Bob verifying Grace’s signature, and that would require trusting that Grace didn’t make a unique signature that she only used for Alice, and making a note of who verified it.
There might be a way to verify those signatures with public keys in a way that didn’t require Bob to tell Grace that he was verifying the signature, which is still rattling around in my brain.
Bob would have to know and trust Grace beforehand. Grace could be the IRS, for example. The idea here being to have somebody who already knows your age vouch for your age.
That’s not about Bob trusting Grace specifically (that’s a premise of the entire operation), it’s about trusting that the letter Alice handed Bob was actually signed by Grace.
Well, if Grace is already well known, then her public key should be available.
That…seems so obvious, now that you say it.
The problem is that it leaves a paper trail.
Grace also knows what number n got verified, and the identity of the user n. Later, the website can ask the age-verifying service who user n actually was. It requires that the age-verifying service cooperates with the website, though, but this could be mandated by law, which would create a single point of (privacy) failure.
PS: i love your writing style. It’s so simple and clear :)
Cryptography is a really complicated subject. You managed to express it very easily understandable.
Yeah, that is a problem.
And thanks for the compliment.
See my comment in this thread involving drawing a piece of paper from a box in real life. Since nobody knows which piece of paper you draw from a box, if many people do this at the same time, it’s impossible to establish an one-to-one mapping between age-verifying tokens and people’s identities.
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.
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.
The kids are just bait for the masses, the big bad wolf doesn’t care about the safety. Control is what they’re after.
Besides that the point about guardrails, is what I agree in. It would prove beneficial for kids until they become fully aware teenagers. It is also beneficial to note the lack of distinction between teens and kids within these laws. This is what truly makes this predatory - where the fully aware individuals are stripped off their rights.
If they are going to take away the rights of our children, teens & adolescents, what is stopping them from taking away our rights?
Yeah, there is a massive difference between a 9 year old and a 14 year old. Someone who is 17 is not necessarily significantly different from an 18 year old, yet we have to draw the line somewhere. I think if you own and pay for the service it should be up to you at a service level, not up to the government to demand a random third party company be accessed to verify ID and so on. That third party company stands to make money while also being a wonderful target for hackers.
That brings us to the whole concept of the internet. Decentralisation. Everyone at this point is impacted; and while age is being used as a weapon, the internet is becoming more and more centralised.
Amazon and cloudflare outages were warnings before the real storm. Decentralisation is where we should strive for - and yet the only thing this proves, is the naiveness and the lack of understanding the people that make these laws have.
It is possible, but the real goal is about removing anonymity altogether
Super easy. Technology has existed for quite some time and was already used in the encrpytion of web traffic.
Basically: you sign up with your “age verification institution” (ideally a service of your government because they have your ID anyway and no profit motive). This involves createing a private key (reaaaaaaaaaaly long password that is saved in a file on your device) and saving the public key with that institution. They also check your ID to ensure your identity and your age.
When you want to visit a 18+ website, the website sends you a nonce (loooooong random number). You take that nonce and send it to the verifier, along with a signature of your private key (and the age they want you verified against). The verifier verifies your signature using your public key. They then sign the nonce with their own private key, thereby verifying, that you, the owner of your private key (whos identity and age they have verified) are above the asked age theshould. You then send the signed nonce back to the 18+ website and they can verifiy the signature to confirm that a trusted age verifier has verified your age.
The site never has access to your identity and the verifier never knows which site you visited, only that you wanted to visit a website that wants to know if you are of a certain age.
(The corresponding technology was used for OCSP Stapling in TLS verification … and has been discontinued last year because nobody was using it …)
Technically this works EXCEPT the required third party. Either it’s the government and you have to trust them with information of knowing everything that required age verification or its separate company that can and would sell your data to data brokers. Being free and NOT the government seems mutually exclusive.
The verifier does not have the information which sites you use. That’s the point of the setup. All communication goes through you, never the site to the verifier directly. You only pass cryptographic values between them that does not include identifiable information (neither about you to the website, nor about the website to the verifier). The verifier knows who you are, the website knows that you are old enough. Nothing else.
Oh I missed that separation before. Ok my bad.
Zero-knowledge proofs still require that third party but only once, to issue it initially. Then the user can issue their own proofs locally
So it’s like generating a CA and then signing your own certs.
More like getting a TLS domain cert from a CA both sides recognize, but yeah
You can use a government issued certificate to generate your own age proofs without their involvement.
I doubt this doesn’t actually leave a paper trail.
At some point, you send that nonce to an age-verifier service. So they can keep track of it, and if the 18+ website you visited at some point later wants to know your identity, they can ask the age-verifier service who asked for that nonce to be signed.
This involves that two organizations are corrupt, however: both the 18+ website and the age-verifying service. Law could mandate that they both cooperate, however, thus creating a single point of (privacy) failure.
I still believe it is doable, however. Check my other comment involving a piece of paper that is drawn from a box. My method relies on the fact that the age-verifying service doesn’t actually know which code they gave you, just that they gave you one. For digital services, seevices can always keep track of their input/output, which is not always possible in real life.
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.
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
The verifier does not know what exactly you are proving, when you are proving it or to whom.
The service provided by the verifier is equivalent to a stamp on a piece of paper.
Bad terminology choice, I meant the cert issuer. Need to revise the language later. I was thinking of it in terms of who verifies your IRL identity. The issuer can only issue the cert after you met them and they checked your documentation, etc
In any system there has to be some source of truth to base the data on. Otherwise people can claim anything .
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 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.)
That sounds logical, but I think there would be an immediate black market for valid codes that would be sold to minors.
same for alcohol