this post was submitted on 30 Nov 2024
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Many might've seen the Australian ban of social media for <16 y.o with no idea of how to implement it. There have been mentions of "double blind age verification", but I can't find any information on it.

Out of curiosity, how would you implement this with privacy in mind if you really had to?

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[–] e0qdk@reddthat.com 43 points 10 months ago* (last edited 10 months ago)

Frankly, the only sane option is an "Are you over the age of (whatever is necessary) and willing to view potentially disturbing adult content?" style confirmation.

Anything else is going to become problematic/abusive sooner or later.

[–] letsgo@lemm.ee 32 points 10 months ago (2 children)

Not a cryptographic expert by any means but maybe something like this would work. This'd be implemented in common places people shop: supermarkets for instance. You'd go up to customer service and show your ID for visual confirmation only; no records can be created. In return the service rep would give you a list of randomised GUIDs against which the only permissible record can be "has been taken". Each time you need to prove your age you'd feed in one of those GUIDs.

[–] nutsack@lemmy.world 7 points 10 months ago (1 children)

this is an actual answer which is therefore interesting

[–] litchralee@sh.itjust.works 15 points 10 months ago* (last edited 10 months ago) (1 children)

Sadly, this type of scheme suffers from: 1) repudiation, and 2) transferability. An ideal system would be non-repudiable, meaning that when a GUID is used, it is unmistakably an action that could only be undertaken by the age-verified person. But a GUID cannot guarantee that, since it's easy enough for an adult to start selling their valid GUIDs online to the highest bidder en-masse. And being a simple string, it can easily and confidentially be transferred to the buyer, so that no one but those two would know that the transaction actually took place, or which GUID was passed along.

As a general rule, when complex questions arise which might possibly be solved by encryption, it's fairly safe to assume that expert cryptographers have already looked at the problem and that no easy or obvious solution exists. That's not to say that cryptographers must never be questioned, but that the field is complicated enough that incomplete answers abound.

IMO, the other comments have it right: there does not exist a general solution to validate age without also compromising anonymity or revealing one's identity to someone. And that alone is already a privacy compromise.

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[–] conciselyverbose@sh.itjust.works 28 points 10 months ago

You can't.

Age verification is not compatible with any remotely acceptable version of the internet. It's an obscene privacy violation in all cases by definition.

Any implementation short of a webcam watching you while you use the site is less than trivial to bypass with someone else's ID while opening numerous massive tracking/security holes for no reason.

[–] Asidonhopo@lemmy.world 23 points 10 months ago (2 children)

I seem to remember Leisure Suit Larry verified age using trivia questions that only older people would answer correctly. I know this because at 8 years old I guessed enough of them on my father's friends computer to play it.

[–] onlinepersona@programming.dev 8 points 10 months ago

oof, I'd fail trivia questions for my age group because I had a... complicated childhood. But it would probably be a problem for foreigners who didn't grow up the country. Imagine coming from Chile and having to know about Australian trivia from the 70s or something to sign up for a social media platform 😄

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[–] Kissaki@programming.dev 2 points 10 months ago (1 children)

I talked to a friend of mine last week and they didn't know of the old PS/2 mouse/keyboard cable/sockets. They've seen it before, but it wasn't familiar to them. Nobody only having used USB devices will remember those.

[–] Asidonhopo@lemmy.world 2 points 10 months ago (1 children)

I was just getting used to PS/2 connectors replacing serial mice and keyboards and then friggin USB comes along....

[–] Kissaki@programming.dev 2 points 10 months ago* (last edited 10 months ago)

Tell me when you're getting used to USB so I can prepare for the next switch /s 😅

[–] incogtino@lemmy.zip 22 points 10 months ago (2 children)

A joke answer, but with the kernel of truth - IRL age verification often requires a trusted verifier (working under threat of substantial penalty) but often doesn't require that verifier to maintain any documentation on individual verification actions

https://chinwag.au/verification/

[–] onlinepersona@programming.dev 5 points 10 months ago (4 children)

As in, you have to roll up to an "age verification bureau" and say "I'd like to sign up to $platform, please verify that I'm of legal age to use it and tell them so", then you buy a "token" that you can enter upon signing up? Am I understanding that correctly?

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[–] VonReposti@feddit.dk 3 points 10 months ago

Sounds quite a lot like zero-knowledge proof

[–] incogtino@lemmy.zip 3 points 10 months ago* (last edited 10 months ago)

I wasn't thinking in detail, just addressing an assumption I think a lot of age verification discussions include, which is that the verifier would have to be trusted to maintain some sort of account for you, retaining your data etc.

I have no idea what the legislation says, but I'd be a happier privacy-conscious user if the verification platforms were independent (i.e. not in any other data business) and regulated, with a requirement they don't retain my personal data at all (like the liquor store example)

So the verifier gathers data from you, matches it with a request from the platform, provides confirmation that some standard has been met, and deletes almost all personal information - I acknowledge that this may not rise to the double-blind standard of the original request

Edited to add:

  • you don't have to 'buy' a token, the platform needs to pay verifiers as a cost of business

  • some other comments are asking how you prevent the verifier knowing the platform - to my mind you don't, instead the verifier retains a request id record from the platform, but forgets entirely who you are

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[–] rcbrk@lemmy.ml 2 points 10 months ago

Ah, easy then: lower the drinking age from 18 to 16.

[–] Draconic_NEO@programming.dev 19 points 10 months ago

It can't. It requires invasion of privacy to verify information about the individual they don't have the right to access.

Digital age verification goes against privacy. Let's not delude ourselves into thinking it can.

[–] PlexSheep@infosec.pub 16 points 10 months ago* (last edited 10 months ago) (1 children)

If the governments would get their shit together, we could have something like age assertion with the eid chips in our IDs. Imagine that. The important thing is that website.com just asks the government "is this user an adult?" And the government replies "yes". No information besides the relevant one is provided, and it's through a trusted authority.

Yeah, not gonna happen, just like using the keys in my Personalausweis to send encrypted mail.

[–] FooBarrington@lemmy.world 11 points 10 months ago (1 children)

The system would have to be built so that the government can't connect the user to the website, as you don't want the government to build profiles on website usage by person. Though the bigger challenge here is trust - even a technically perfect system could be circumvented by the operators.

A good example for this were the COVID tracking apps. The approach was built so that as little information was leaked as possible.

[–] Buddahriffic@lemmy.world 5 points 10 months ago (1 children)

Could have a system where a government site cryptographically signs a birth year plus random token provided by the site you want to use.

Step 1: access site
Step 2: site sends random token
Step 3: user's browser sends token plus user authentication information
Step 4: gov site replies with a string containing birth year, token, and signature
Step 5: send that string to the other site where it uses the government's public key to verify the signature, showing the birth year is attested by the government

No need to have any direct connection with the user's identity and the site or been the gov and site.

[–] Miaou@jlai.lu 2 points 10 months ago* (last edited 10 months ago)

Unless the government buys the generated tokens from those websites. That's like the entire problem

[–] MajorHavoc@programming.dev 15 points 10 months ago (1 children)

If I really had to, I would require everyone to whip out whatever assets of sexual maturity they happen to have, and let the computer analyze it and decide a maturity level.

I would also keep copies for blackmail purposes, because the world is a better place if we all mistrust this solution and anything remotely like it. It'll be in the legal fine print, which I'm confident no one will read.

Every answer (other than "trust the user to self identify") is at least remotely like mine, but I'm proposing we cut out the half-measures on the way.

To avoid personal consequences, the system I architect will probably wait on a dead-man-switch for me to die or be incarcerated.

Then it will publish everything it has ever seen, along with AI generated commentary. I'm confident that some of it will be hilarious, and I am hopeful that it will piss everyone off enough that we stop doing this kind of thing.

[–] zlatko@programming.dev 2 points 10 months ago

So, send'em a dicpic and you're in :)

[–] chaospatterns@lemmy.world 14 points 10 months ago* (last edited 10 months ago) (3 children)

Its possible to implement something that hides your actual age from a website, but the tricky part is hiding what website you're visiting from an identity provider.

Let's walk through a wrong solution to get some fundamentals. If you're familiar with SSO login, a website makes a request token to login the user and makes claims (these request pieces of user information.) One could simply request "is the user older than 18?" And that hides the actual age and user identity.

The problem is how do you hide what website you're going to from the identity provider? In most SSO style logins, you need to know the web page to redirect back to the original site. Thus leaking information about websites you probably don't want to share.

The problem with proposals that focus on the crypto is that they actually have to be implemented using today's browser and HTTP standards to get people to use them.

[–] iknowitwheniseeit@lemmynsfw.com 3 points 10 months ago

It can be done. The website provider can generate a request that it forwards to you. You then pass on this request to the age verifier, who can answer "yes person is over 16" without knowing why you want to know, or who generated the request.

The requester wouldn't know your age, just that you were old enough.

There are a few problems.

One is that the website could embed some identifier in the signature of their request. But any information there can be easily send by the web site provider to the age verifier directly if they wanted so this is not a big problem.

Another problem is that the age verifier could look at times when requests were submitted and create a sort of "fingerprint" based on when requests arrived for different sites. This could be partially helped by having browsers request age verification randomly in the background any time you use a browser.

[–] hemko@lemmy.dbzer0.com 2 points 10 months ago (2 children)

Could it be maybe a token signed by the verifying party living permanently on your computer (like cookie), and websites can request permission to query it to verify the age?

[–] sukhmel@programming.dev 4 points 10 months ago (1 children)

Since age tends to not decrease, that may make sense: once you reach 18 you get a signed token you can use forever.

Your token might be used by someone else, though

[–] MajorHavoc@programming.dev 5 points 10 months ago (1 children)

Your token might be used by someone else, though

Yeah. I feel like that cool bad influence not-actually-my-uncle is gonna publish their porn access token everywhere.

[–] hemko@lemmy.dbzer0.com 4 points 10 months ago

Porn Access Token lmao

[–] chaospatterns@lemmy.world 3 points 10 months ago

The hard part is browsers. Cookies and local storage are limited by the origin URL. You need it explicitly set on the domains you intend to visit, but those domains don't know your age. The one that knows the age is the identity provider, but it can't set it for all domains. There are other techniques that you could use, like a smart card combined with a browser extension to do local based user info attestation, but those are difficult to manage at a nation scale and I suspect people will struggle with them, though there are some countries that do have national smart cards (e.g. Estonia.)

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[–] Simulation6@sopuli.xyz 14 points 10 months ago (1 children)

Sites are just going to ask people 'Are you over 16? (Y/N)'. Site is now legally covered, and that is all anyone cares about.

[–] Aussiemandeus@aussie.zone 2 points 10 months ago

Just like porn and grog is Australia already .

Not to mention my space you needed to be over 16vor something so we all lied

[–] eyeon@lemmy.world 10 points 10 months ago (4 children)

All I can think of are some variations of you trusting a service to validate your id and give you a token that just asserts your id has been validated.

But it's still not really privacy preserving because it relies on trusting both parties to not collaborate against your privacy. if at some point the id provider decides to start keeping records of what tokens were generated from your id, and the service provider tracking what was consumes with that token, then you can still put it all back together.

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[–] ben_dover@lemmy.ml 6 points 10 months ago (2 children)

in blockchain tech, there's the concept of "zero knowledge proofs", where you can prove having certain information without revealing the info itself

[–] sinceasdf@lemmy.world 5 points 10 months ago

Would be interesting to see a govt tackle setting up a trustless system like it required for cybersecurity best practices. I think it's a thorny issue without a trusted authority though.

What stops an ID for being posted publicly or shared en masse? So one ID can be used unlimited times - just share the key with minors for $1 at no risk to oneself since there's no knowledge of the 'transaction' being sent around. Better for individual privacy but that undermines the political impetus for wanting the verification. Usage would probably have to be monitored or capped, kind of defeating the advantage of the anonymous protocol (or accept that abuse is unenforceable).

[–] IphtashuFitz@lemmy.world 3 points 10 months ago (1 children)

So how would you use it to solve this problem? There still needs to be some sort of foolproof way of saying “person X is only 14 years old”.

[–] planish@sh.itjust.works 6 points 10 months ago

You would prove something like "I possess a private key that matches a public key that is in this list of public keys belonging to people at least X years old". But without revealing which item in the list is the specific one for you. Which is the zero knowledge proofs' cool trick.

[–] Kissaki@programming.dev 6 points 10 months ago* (last edited 10 months ago) (1 children)

Who has age authority? A state agency or service. Like the state issues an ID with age.

Preferable, we want the user to interact with a website, that website request age authentication, but not the website to talk to the government, but through the user.

Thus, something/somewhat like

  1. State agency issues a certificate to the user
  2. User assigns a password to encrypt the user certificate
  3. User connects to random website A
  4. Random website A creates an age verification request signed to only be resolveable by state agency but sends it to the user
  5. User sends the request to a state service with their user certificate for authentication
  6. State agency confirms-signs the response
  7. User passes the responds along to the random website A

There may be alternative, simpler, or less verbose/complicated alternatives. But I'm sure it would be possible, and I think it lays out how "double-blind"(?) could work.

The random website A does not know the identity or age of the user - only to the degree they requested to verify - and the state agency knows only of a request, not its origin or application - to the degree the request and user pass-along includes.

[–] robinm@programming.dev 2 points 10 months ago

I never realised it was that simple to do. Thanks a lot to answer the OP question. I had the same for longer than I wish to admit given how easy the answer was!

[–] chicken@lemmy.dbzer0.com 5 points 10 months ago
[–] pineapplelover@lemm.ee 5 points 10 months ago

Well Australia will probably so something privacy invading and fascist.

I guess if you want it to be somewhat private you could have some kind of hash or token generated from your identification information. I bet that would be fairly private

[–] Korne127@lemmy.world 5 points 10 months ago
[–] socsa@piefed.social 2 points 10 months ago

It can't be. The entire concept is a Trojan horse to kill the anonymous internet.

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