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by Nursie 46 days ago
Restricted-site.com gets the signed response from the broker, not the bank. In your situation there's not any need for "everyoneisover18.com" to defer to a real bank for a faked response as it signs things itself.

But restricted-site.com doesn't trust everyoneisover18.com's key, it only trusts realbroker.com's key, so the response isn't accepted. If it is found to trust fake brokers like that it gets in trouble with the law.
1 comments
tardedmeme 46 days ago
That's why everyoneisover18.com forwards the request to my bank or my broker and gets my signature on the behalf of literally anyone. I may charge them $5 for this service.
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Nursie 46 days ago
> That's why everyoneisover18.com forwards the request to my bank or my broker

Doesn't work. The response won't be signed by real-broker.com.

The permission request/response itself goes direct from the server at restricted-site.com to the server at real-broker.com over TLS, so you can't MITM it, it's not controlled by the client and you won't be able to just pass out a cached response.

Your malicious client plugin could potentially forward the client session details to you, so you could operate the broker page, then log in to your bank's portal and approve that request, but I don't think that's going to scale very well and I imagine your bank is likely going to rate limit you.

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tardedmeme 46 days ago
real-broker opens a web page allowing them to verify somehow. The browser extension sends me their URL and cookies so I can load the same page and verify myself. All automated of course.
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Nursie 46 days ago
You could, you could also go to their house and go through the process for them, but in either case I don't think it's going to scale very well (rate-limiting would seem to be called for, maybe with 2FA as well, to mitigate this sort of thing and remove the possibilities for automation).

But sure, you could subvert it on a small scale, just as you can borrow someone else's driving license to register in 'normal' systems already. You could also register an account, validate it and then sell the login details, regardless of what proof of age scheme you use.

The point is the scheme is no worse at validation than asking for ID and it protects user privacy by keeping all ID details away from individual websites, which is the more important part IMHO.

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tardedmeme 46 days ago
What rate limit would you recommend?

My cellphone provider will be pleased be paid to deliver all those 2FA text messages. Who's sending them? How are they getting paid? Maybe I'm actually my own phone company, so I get paid for delivering them to myself.

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Nursie 46 days ago
> Who's sending them?

Your bank, like they have 2FA for every other access to your account. 2FA also doesn't need to be via SMS, and even when it is that's dirt cheap. Rate limits can be a couple of approvals per hour with daily limits of a small handful. Or a leaky-bucket style algortihm where you can do a few at a time, but you only get one more per hour. Whatever way it's done it precludes your large-scale automation attempt.

I tire of this now. We've entirely wandered off from "Here's a way to prove age without the privacy implications, that works just as well as handing over scans of ID"

So if you have an actual point, please make it.

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