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> Much like age verification Age verification as a technical concept can be done in a privacy-preserving manner! Whether or not we want age verification is ano

by palata 6mo ago

> Much like age verification Age verification as a technical concept can be done in a privacy-preserving manner! Whether or not we want age verification is another debate, but let's stop making wrong technical claims about that: it doesn't help.

bpfrh 6mo ago
Really, how? At some point someone will need to issue a key, which at some point will need to be verified against known good signatures. These signatures will also need to be kept in case of lawsuirs/enforcement, so if somebody gets access they will know you visited that site
- palata 6mo ago
  With cryptography. Look at e.g. Privacy Pass, there is an RFC about it.
- maccard 6mo ago
  Ring cryptography does this - given a public key and a set of private keys you can attest that one of the keys signed it but not which one. This lets both Google and you generate a signature and say “this is attested”, without the person verifying it knowing _who_ signed it.
  - nullc 6mo ago
    You likely need one other step beyond a plain ring signature, often called a linkable ring signature. If you use only a plain ring signature I could get one authenticated key and setup a site that gives away an unlimited number of access tokens with it, and you can't identify which key is doing so in order to kick it out. A linkable ring signature lets you correlate multiple usage but only if they share a common 'context value'. Intelligent selection of the context value results in abusive use inevitably sharing a context so you can exclude or rate limit it, but honest use tends to not share a context so the privacy is preserved.
- Scaled 6mo ago
  Parental controls on device are a better solution that work today and don't carry a risk of data breach.
  - harshreality 6mo ago
    They would be a solution if almost all parents used them, but parents don't want to socially isolate their kids since a lot of "social" activity is now on social media. It's kind of a prisoner's dilemma. There's not necessarily wrong. Despite the vapid and damaging nature of most popular online media, isolating a child from it might have even worse social consequences when their real-life peer groups discover that they're not on social media or that their parents have neutered their phone. Some kids would turn out fine after that. Others would be socially destroyed for life (maybe with the right therapy they could become well-adjusted, but high quality therapy is rare).
    - JoshTriplett 6mo ago
      > They would be a solution if almost all parents used them No, they are a solution for parents who want to use them, and that's all they should be. Their existence demonstrates that it's possible to handle this without regulation, other than the desire of some people to inflict their preferences onto other people's kids.
      - sumeno 6mo ago
        You haven't tried to use parental controls much have you? They are all terrible. They are insanely difficult to get set up properly and even when you do there are a lot of tradeoffs that come with it.
        JoshTriplett 6mo ago
        > even when you do there are a lot of tradeoffs that come with it Absolutely, but those are nothing compared to the tradeoffs of putting attestation or identity verification (sometimes incorrectly described as "age" verification) on numerous sites and inflicting them on everyone.
- michaelt 6mo ago
  The trick is to define "privacy-preserving age verification" in an extremely narrow way that ignores any other privacy concerns. For example, imagine you put the same private key into the 'secure element' of every single iphone. You use code signing so that key is only unlocked when the phone is running unmodified iOS with all security updates. You use encryption and remote attestation for the front-facing camera and face id depth sensor. You use NFC to read government-authenticated age and appearance data from biometric passport chips (or digital ID cards) and you store it on-device. Then, when you want to access pornhub, they send an age challenge to your device, your device makes sure your face matches the stored passport, and if so it signs the challenge with the private key. Pornhub gets an Apple-signed attestation of age - but because every phone signs with challenges with the same private key, Pornhub can't link it to a particular phone or identity document. So in a very narrow sense, privacy is preserved. You can't use someone else's ID, as it checks your face every time. You can't fool it with a photo of the person because of the depth sensor. You can't MITM/replay the camera/depth data because the link is encrypted. You can't substitute software that skips the check with a rooted phone because of the code signing. Security holes can be closed by just pushing a mandatory OS update. Sure, it doesn't work on PCs. Doesn't work on Linux, or on unlocked/rooted phones. It hands users' government ID documents over to Google and Apple. It requires people to carry foreign-made, battery powered, network connected GPS trackers (with cameras, microphones and speech recognition) with them. And there are non-negotiable terms of service everyone must agree to. But if you define "privacy-preserving" to ignore all that stuff and only consider whether Pornhub learns your identity, it's privacy-preserving.
  - palata 6mo ago
    Wait what? All the time you spent writing that nonsense could have been invested in reading about how it actually works.
  - chmod775 6mo ago
    That key will get leaked. A key that has to go into every phone, even if done at the manufacturer and onto the TPM chip, will get out. Also even if it doesn't get leaked directly, the security of TPM chips is not absolute. Secrets from them can theoretically be extracted given an attacker with sufficient means and motivation. Normally nothing that's on a typical TPM chip would warrant a project of that magnitude, but a widely used private key can change that equation. Plus a TPM chip doesn't really have means to tell the phone isn't being lied to. You could swap out the actual phone camera hardware and sensors for a custom board that feeds the entire phone camera data of your choosing and it would be none-the-wiser.
- ForHackernews 6mo ago
  https://ageverification.dev/ https://ageverification.dev/ > Unlinkability is achieved by design through Zero-Knowledge Proof cryptography see the "Privacy by design" section below.
- Arch-TK 6mo ago
  It should be possible with zero knowledge proofs. The problem is that while you might be able to trust the crypto, the government won't trust you to do the crypto entirely by yourself. And this introduces avenues for deanonymisation. Moreover, collusion between the government and the entity making the age check can also theoretically deanonimize. It's a complicated problem. We continue to seek a technological solution to a parenting problem.
  - palata 6mo ago
    > Moreover, collusion between the government and the entity making the age check can also theoretically deanonimize. Hmmm... no? That's not how zero knowledge works.
    - Arch-TK 6mo ago
      Not via breaking the ZKP, but via other methods of fingerprinting, which governments are very well positioned to enable.
      - palata 6mo ago
        I feel like it becomes bad faith at some point. With a sufficiently advanced attack, you can be personally identified today. ZKP for age verification does not make this worse, does it? It's a bit like saying "no but Signal is not really encrypted, because the government can extract some metadata by looking at the network around the server".
- andrepd 6mo ago
  All states/governments have basic records on their citizens and residents, including at least a name, dob, address, etc, at least for a passport, driver's license, if not an actual id card. Let's assume this is acceptable. Then it's technically possible (and really not that difficult) for states to provide a service that issues zero-knowledge proofs of facts like "age > X".
  - AdrianB1 6mo ago
    > Let's assume this is acceptable. (partly off-topic rant) One can argue this is a false premise fallacy. For most of the time states did not have this information about their citizens and the world progressed quite nicely. The only argument to know stuff about citizens that don't drive (increasing numbers) nor travel abroad (different problem altogether) is to tax them? One of the foundational differences between humans and cattle was you cannot brand (https://en.wikipedia.org/wiki/Livestock_branding https://en.wikipedia.org/wiki/Livestock_branding) humans. Not physically, because we do it digitally and I see a slippery slope.
    - andrepd 6mo ago
      The discussion was about age verification, not about the (rather more extreme) position that it's illegitimate for the state to hold information about its citizens. > For most of the time states did not have this information about their citizens and the world progressed quite nicely. This is quite untrue. State bureaucracies far predate the modern era.
- red_admiral 6mo ago
  Blind signatures would work, with a bit of effort.
- nullc 6mo ago
  You can prove your signature is from a key which is in a member of an acceptable set without revealing which one. These schemes can also prevent excessive reuse, e.g. by you also proving that some linked value is a hashlike function of your private key, the date, and the domain, so if you sign multiple times for the same site in the same day your uses are linked, so someone can't just toss up an oracle that gives endless authentications. Such systems are deployed in production by privacy preserving cryptocurrencies as its the same problem: Prove you're spending a coin that exists without revealing information about which one, and prove that you're not spending it multiple times. Less private but easier to implement is just simple blind signing. Site asks you to give them a signature of their domain name, your account name, and date. You blind the data using a random number, go to google and identify yourself (e.g. solve a CAPTCHA, check your mobile device, age verify, whatever) and ask them to sign the blinded value-- they rate limit you and give you a signature. You unblind and provide to the site. Now the site knows you passed the google rate limit but nothing else, but google never learns what site you authenticated to. The blindsigning approach is kinda lame because it requires active communication with a third party that learns you're online and authenticating to stuff. So I think it's generally less preferred but the cryptography is hardly any more complicated than an ordinary digital signature.
- brookst 6mo ago
  Look at Apple’s PAT: the website knows the service that did the attestation, but not the user. The service knows the user, but not the website. If you controlled both you can link the user, but otherwise you can’t.
  - palata 6mo ago
    Yes, but they can still collude. It's possible to do age verification in a way that prevents that. Look e.g. at Privacy Pass.
    - brookst 6mo ago
      PAT is Privacy Pass.
      - palata 6mo ago
        Oh right, my bad. And how can they collude there?
- drewgross 6mo ago
  It doesn't provide 100% privacy from everyone, but it does provide privacy from the web service: A worker at a physical store checks your ID, and if it says you are 18, they hand you a token with a unique key on it, which they have a stack of behind the counter. You put the unique key into the web service. It's not necessarily one time use, but if you don't want to risk correlation, you can use each one only once. It's just like alcohol sales, and has all the same failure modes as alcohol sales, but if it's good enough for alcohol sales it's good enough for web services.
  - fc417fc802 6mo ago
    Well it probably needs a bit more complexity to avoid being trivially broken. Codes are one time use; the service has them attested by the token provider behind the scenes, and the provider is in turn under contract with the government. Tokens are also activated at the point of purchase similar to gift cards in order to prevent bulk theft and resale. A law in the vein of HIPAA prevents collusion between the retail establishment and the token provider.
    - palata 6mo ago
      People, you have to read about zero knowledge proofs. Look at e.g. Privacy Pass. > A law in the vein of HIPAA prevents collusion No need if you use cryptography. This thing that, you know, works well for encrypting stuff? Spoiler: it can be used for age verification.
      - rstuart4133 6mo ago
        >> A law in the vein of HIPAA prevents collusion > > No need if you use cryptography. True for age verification, but not true in general. If you have something that can be used illegally, it's very handy to allow firms to rent / hire it out anyway but make the hirer responsible for any illegal activity. An example is hiring a car, and the car is used to ram-raid a shop. Today this is solved by handing over a government ID to the rental company. Commit a crime in the car and they hand that over to police, but it has the sad side effect of handing over information to the car rental they can use to track you, and worse sell to others. Using a zero knowledge proof for a valid driver's licence fixes the privacy problem, but at the expense of the hire company not being able to transfer responsibility for illegal activity onto the hirer. I suspect if that happened no one would hire out cars any more. You can easily design something that is Zero Knowledge to the car hire firm, but includes an opaque token they can hand over to the government on lawful demand. It contains all the details needed to pursue the law breaking hirer. Thus there is still a role for the law here - you can't always do everything with crypto. This is a very minor quibble - I agree completely with what I think is your main point. This Google change is a privacy disaster. It's a step towards an enshittified internet with the gateways onto it controlled by a few big tech firms. But I don't think just yelling "just use ZK" is helpful. It's much harder than that - ZK is only part of the puzzle. Passkeys are currently caught up in the same attestation trap, and there is no workable solution in the offing. Banks and other high trust applications need some assurance your FIDO private key is being handled securely. The solutions on the table are Apple not doing attestation, or Google who does at the low low price of selling your true name to Google. Both "solutions" suck, horribly. ZK proofs of things like licences and age have to solve the attestation problem, and solve extra stuff as well. I'm not holding my breath.
indymike 6mo ago
Divorcing technical detail from how it is used does little good for humanity.
pdntspa 6mo ago
Doesn't matter if it is privacy preserving, it is still an evil thing to do
- palata 6mo ago
  That would be the interesting debate, if people could actually spend 5min learning how it works and stop claiming nonsense.
jollymonATX 6mo ago
Exactly the mindset that got us to this current reality..
coppsilgold 6mo ago
As far as I know no currently proposed age verification method does this in practice. The only way to implement truly privacy preserving age verification is through zero knowledge proofs (or blind signatures) but what that would allow is undetectable token forging.
- YourDadVPN 6mo ago
  The EU's proposed system uses ZK proof. You get a PGP signed message from "someone" who knows your identity (government or private agency) then store it on your phone to pass to websites that need your age. It does have an obvious flaw in that whoever you give the token to has no proof it's actually yours. https://ageverification.dev/av-doc-technical-specification/docs/architecture-and-technical-specifications/#132-acronyms-and-abbreviations https://ageverification.dev/av-doc-technical-specification/d...
  - palata 6mo ago
    > It does have an obvious flaw in that whoever you give the token to has no proof it's actually yours. Which isn't necessarily a flaw, depends on the threat model. For actual age verification that we care about (e.g. make it harder for kids to access social media), it may be good enough.
  - coppsilgold 6mo ago
    This is not sufficient. Do they give you a blind signature? Because what you described does not preserve your anonymity if the government and the service collude.
account42 6mo ago
No it can't. If it's done in a truly privacy preserving way then someone can also sell a fake age verification service making the whole thing meaningless.

by palata 6mo ago

bpfrh 6mo ago

Really, how? At some point someone will need to issue a key, which at some point will need to be verified against known good signatures. These signatures will also need to be kept in case of lawsuirs/enforcement, so if somebody gets access they will know you visited that site

palata 6mo ago
With cryptography. Look at e.g. Privacy Pass, there is an RFC about it.
maccard 6mo ago
Ring cryptography does this - given a public key and a set of private keys you can attest that one of the keys signed it but not which one. This lets both Google and you generate a signature and say “this is attested”, without the person verifying it knowing _who_ signed it.
- nullc 6mo ago
  You likely need one other step beyond a plain ring signature, often called a linkable ring signature. If you use only a plain ring signature I could get one authenticated key and setup a site that gives away an unlimited number of access tokens with it, and you can't identify which key is doing so in order to kick it out. A linkable ring signature lets you correlate multiple usage but only if they share a common 'context value'. Intelligent selection of the context value results in abusive use inevitably sharing a context so you can exclude or rate limit it, but honest use tends to not share a context so the privacy is preserved.
Scaled 6mo ago
Parental controls on device are a better solution that work today and don't carry a risk of data breach.
- harshreality 6mo ago
  They would be a solution if almost all parents used them, but parents don't want to socially isolate their kids since a lot of "social" activity is now on social media. It's kind of a prisoner's dilemma. There's not necessarily wrong. Despite the vapid and damaging nature of most popular online media, isolating a child from it might have even worse social consequences when their real-life peer groups discover that they're not on social media or that their parents have neutered their phone. Some kids would turn out fine after that. Others would be socially destroyed for life (maybe with the right therapy they could become well-adjusted, but high quality therapy is rare).
  - JoshTriplett 6mo ago
    > They would be a solution if almost all parents used them No, they are a solution for parents who want to use them, and that's all they should be. Their existence demonstrates that it's possible to handle this without regulation, other than the desire of some people to inflict their preferences onto other people's kids.
    - sumeno 6mo ago
      You haven't tried to use parental controls much have you? They are all terrible. They are insanely difficult to get set up properly and even when you do there are a lot of tradeoffs that come with it.
      - JoshTriplett 6mo ago
        > even when you do there are a lot of tradeoffs that come with it Absolutely, but those are nothing compared to the tradeoffs of putting attestation or identity verification (sometimes incorrectly described as "age" verification) on numerous sites and inflicting them on everyone.
michaelt 6mo ago
The trick is to define "privacy-preserving age verification" in an extremely narrow way that ignores any other privacy concerns. For example, imagine you put the same private key into the 'secure element' of every single iphone. You use code signing so that key is only unlocked when the phone is running unmodified iOS with all security updates. You use encryption and remote attestation for the front-facing camera and face id depth sensor. You use NFC to read government-authenticated age and appearance data from biometric passport chips (or digital ID cards) and you store it on-device. Then, when you want to access pornhub, they send an age challenge to your device, your device makes sure your face matches the stored passport, and if so it signs the challenge with the private key. Pornhub gets an Apple-signed attestation of age - but because every phone signs with challenges with the same private key, Pornhub can't link it to a particular phone or identity document. So in a very narrow sense, privacy is preserved. You can't use someone else's ID, as it checks your face every time. You can't fool it with a photo of the person because of the depth sensor. You can't MITM/replay the camera/depth data because the link is encrypted. You can't substitute software that skips the check with a rooted phone because of the code signing. Security holes can be closed by just pushing a mandatory OS update. Sure, it doesn't work on PCs. Doesn't work on Linux, or on unlocked/rooted phones. It hands users' government ID documents over to Google and Apple. It requires people to carry foreign-made, battery powered, network connected GPS trackers (with cameras, microphones and speech recognition) with them. And there are non-negotiable terms of service everyone must agree to. But if you define "privacy-preserving" to ignore all that stuff and only consider whether Pornhub learns your identity, it's privacy-preserving.
- palata 6mo ago
  Wait what? All the time you spent writing that nonsense could have been invested in reading about how it actually works.
- chmod775 6mo ago
  That key will get leaked. A key that has to go into every phone, even if done at the manufacturer and onto the TPM chip, will get out. Also even if it doesn't get leaked directly, the security of TPM chips is not absolute. Secrets from them can theoretically be extracted given an attacker with sufficient means and motivation. Normally nothing that's on a typical TPM chip would warrant a project of that magnitude, but a widely used private key can change that equation. Plus a TPM chip doesn't really have means to tell the phone isn't being lied to. You could swap out the actual phone camera hardware and sensors for a custom board that feeds the entire phone camera data of your choosing and it would be none-the-wiser.
ForHackernews 6mo ago
https://ageverification.dev/ https://ageverification.dev/ > Unlinkability is achieved by design through Zero-Knowledge Proof cryptography see the "Privacy by design" section below.
Arch-TK 6mo ago
It should be possible with zero knowledge proofs. The problem is that while you might be able to trust the crypto, the government won't trust you to do the crypto entirely by yourself. And this introduces avenues for deanonymisation. Moreover, collusion between the government and the entity making the age check can also theoretically deanonimize. It's a complicated problem. We continue to seek a technological solution to a parenting problem.
- palata 6mo ago
  > Moreover, collusion between the government and the entity making the age check can also theoretically deanonimize. Hmmm... no? That's not how zero knowledge works.
  - Arch-TK 6mo ago
    Not via breaking the ZKP, but via other methods of fingerprinting, which governments are very well positioned to enable.
    - palata 6mo ago
      I feel like it becomes bad faith at some point. With a sufficiently advanced attack, you can be personally identified today. ZKP for age verification does not make this worse, does it? It's a bit like saying "no but Signal is not really encrypted, because the government can extract some metadata by looking at the network around the server".
andrepd 6mo ago
All states/governments have basic records on their citizens and residents, including at least a name, dob, address, etc, at least for a passport, driver's license, if not an actual id card. Let's assume this is acceptable. Then it's technically possible (and really not that difficult) for states to provide a service that issues zero-knowledge proofs of facts like "age > X".
- AdrianB1 6mo ago
  > Let's assume this is acceptable. (partly off-topic rant) One can argue this is a false premise fallacy. For most of the time states did not have this information about their citizens and the world progressed quite nicely. The only argument to know stuff about citizens that don't drive (increasing numbers) nor travel abroad (different problem altogether) is to tax them? One of the foundational differences between humans and cattle was you cannot brand (https://en.wikipedia.org/wiki/Livestock_branding https://en.wikipedia.org/wiki/Livestock_branding) humans. Not physically, because we do it digitally and I see a slippery slope.
  - andrepd 6mo ago
    The discussion was about age verification, not about the (rather more extreme) position that it's illegitimate for the state to hold information about its citizens. > For most of the time states did not have this information about their citizens and the world progressed quite nicely. This is quite untrue. State bureaucracies far predate the modern era.
red_admiral 6mo ago
Blind signatures would work, with a bit of effort.
nullc 6mo ago
You can prove your signature is from a key which is in a member of an acceptable set without revealing which one. These schemes can also prevent excessive reuse, e.g. by you also proving that some linked value is a hashlike function of your private key, the date, and the domain, so if you sign multiple times for the same site in the same day your uses are linked, so someone can't just toss up an oracle that gives endless authentications. Such systems are deployed in production by privacy preserving cryptocurrencies as its the same problem: Prove you're spending a coin that exists without revealing information about which one, and prove that you're not spending it multiple times. Less private but easier to implement is just simple blind signing. Site asks you to give them a signature of their domain name, your account name, and date. You blind the data using a random number, go to google and identify yourself (e.g. solve a CAPTCHA, check your mobile device, age verify, whatever) and ask them to sign the blinded value-- they rate limit you and give you a signature. You unblind and provide to the site. Now the site knows you passed the google rate limit but nothing else, but google never learns what site you authenticated to. The blindsigning approach is kinda lame because it requires active communication with a third party that learns you're online and authenticating to stuff. So I think it's generally less preferred but the cryptography is hardly any more complicated than an ordinary digital signature.
brookst 6mo ago
Look at Apple’s PAT: the website knows the service that did the attestation, but not the user. The service knows the user, but not the website. If you controlled both you can link the user, but otherwise you can’t.
- palata 6mo ago
  Yes, but they can still collude. It's possible to do age verification in a way that prevents that. Look e.g. at Privacy Pass.
  - brookst 6mo ago
    PAT is Privacy Pass.
    - palata 6mo ago
      Oh right, my bad. And how can they collude there?
drewgross 6mo ago
It doesn't provide 100% privacy from everyone, but it does provide privacy from the web service: A worker at a physical store checks your ID, and if it says you are 18, they hand you a token with a unique key on it, which they have a stack of behind the counter. You put the unique key into the web service. It's not necessarily one time use, but if you don't want to risk correlation, you can use each one only once. It's just like alcohol sales, and has all the same failure modes as alcohol sales, but if it's good enough for alcohol sales it's good enough for web services.
- fc417fc802 6mo ago
  Well it probably needs a bit more complexity to avoid being trivially broken. Codes are one time use; the service has them attested by the token provider behind the scenes, and the provider is in turn under contract with the government. Tokens are also activated at the point of purchase similar to gift cards in order to prevent bulk theft and resale. A law in the vein of HIPAA prevents collusion between the retail establishment and the token provider.
  - palata 6mo ago
    People, you have to read about zero knowledge proofs. Look at e.g. Privacy Pass. > A law in the vein of HIPAA prevents collusion No need if you use cryptography. This thing that, you know, works well for encrypting stuff? Spoiler: it can be used for age verification.
    - rstuart4133 6mo ago
      >> A law in the vein of HIPAA prevents collusion > > No need if you use cryptography. True for age verification, but not true in general. If you have something that can be used illegally, it's very handy to allow firms to rent / hire it out anyway but make the hirer responsible for any illegal activity. An example is hiring a car, and the car is used to ram-raid a shop. Today this is solved by handing over a government ID to the rental company. Commit a crime in the car and they hand that over to police, but it has the sad side effect of handing over information to the car rental they can use to track you, and worse sell to others. Using a zero knowledge proof for a valid driver's licence fixes the privacy problem, but at the expense of the hire company not being able to transfer responsibility for illegal activity onto the hirer. I suspect if that happened no one would hire out cars any more. You can easily design something that is Zero Knowledge to the car hire firm, but includes an opaque token they can hand over to the government on lawful demand. It contains all the details needed to pursue the law breaking hirer. Thus there is still a role for the law here - you can't always do everything with crypto. This is a very minor quibble - I agree completely with what I think is your main point. This Google change is a privacy disaster. It's a step towards an enshittified internet with the gateways onto it controlled by a few big tech firms. But I don't think just yelling "just use ZK" is helpful. It's much harder than that - ZK is only part of the puzzle. Passkeys are currently caught up in the same attestation trap, and there is no workable solution in the offing. Banks and other high trust applications need some assurance your FIDO private key is being handled securely. The solutions on the table are Apple not doing attestation, or Google who does at the low low price of selling your true name to Google. Both "solutions" suck, horribly. ZK proofs of things like licences and age have to solve the attestation problem, and solve extra stuff as well. I'm not holding my breath.

indymike 6mo ago

Divorcing technical detail from how it is used does little good for humanity.

pdntspa 6mo ago

Doesn't matter if it is privacy preserving, it is still an evil thing to do

palata 6mo ago
That would be the interesting debate, if people could actually spend 5min learning how it works and stop claiming nonsense.

jollymonATX 6mo ago

Exactly the mindset that got us to this current reality..

coppsilgold 6mo ago

As far as I know no currently proposed age verification method does this in practice. The only way to implement truly privacy preserving age verification is through zero knowledge proofs (or blind signatures) but what that would allow is undetectable token forging.

YourDadVPN 6mo ago
The EU's proposed system uses ZK proof. You get a PGP signed message from "someone" who knows your identity (government or private agency) then store it on your phone to pass to websites that need your age. It does have an obvious flaw in that whoever you give the token to has no proof it's actually yours. https://ageverification.dev/av-doc-technical-specification/docs/architecture-and-technical-specifications/#132-acronyms-and-abbreviations https://ageverification.dev/av-doc-technical-specification/d...
- palata 6mo ago
  > It does have an obvious flaw in that whoever you give the token to has no proof it's actually yours. Which isn't necessarily a flaw, depends on the threat model. For actual age verification that we care about (e.g. make it harder for kids to access social media), it may be good enough.
- coppsilgold 6mo ago
  This is not sufficient. Do they give you a blind signature? Because what you described does not preserve your anonymity if the government and the service collude.

account42 6mo ago

No it can't. If it's done in a truly privacy preserving way then someone can also sell a fake age verification service making the whole thing meaningless.