I’d appreciate it if everyone could just stop burning fossil fuels, please. Thank you for your cooperation.

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Joined 1 year ago
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Cake day: November 3rd, 2023

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  • The main reason we can show our physical government-issued ID card to someone in a shop in relative safety is that it’s a human looking at it with their eyes, which do not have the ability to record and permanently store in machine-readable form all the information on it (such as a photo) that would identify their customer. (Of course when they hook up face recognition systems to their surveillance cameras we have other privacy problems, but that’s another story.)

    The same thing cannot so easily be done across the Internet. Something like it may be possible in theory, with some caveats, although it’s hard to tell for sure until we see an actual design document for such a system that is complete to the point where we could examine the details and see if it might really work in practice. Nobody seems to have got that far as of yet. All the actual proposals that I’ve seen sacrifice privacy for convenience of implementation because doing otherwise would be very complicated and difficult.


  • If I search for zero-knowledge proofs relating to age verification the only thing I see is the hash chain method “based on a 2013 paper by Angel & Walfish” which is clever enough but does not in itself solve the problem of proving age while maintaining one’s privacy. It allows Alice to demonstrate to a verifier that she is over the age of 65 while revealing nothing else other than her name or some other identifying piece of information. Avoiding the reveal of any such information is what we would want to avoid.

    Is there some better way to do it?


  • I’m still curious as to what it is that you have in mind. “Yes I have that card” will be communicated to random web services by the user presenting to them some kind of signed digital token I imagine, as is usual, and that token itself, or the user-held secret used in generating it, is what can then be sold, transferred, or used to track the user unless you have some way to prevent that. If you’ve given any hint of how you think it can be done, I didn’t get it.

    One thing people sometimes think of is having the user be authenticated with a government (or other authority) server in real time whenever they want to prove their age to some stranger — but the system I saw which worked like that was obviously a pretty big violation of privacy so I assumed it wasn’t the sort of thing you meant. If that’s the idea, how would you prevent the central authority from keeping a record of when and where your “passport” was used?


  • Uh… if “it doesn’t have to be unique” then you may as well just have a password — everyone who knows that the password is “swordfish” is allowed into the adults-only club. There are things stopping people selling their actual paper-based passports en masse or just making photocopies. If you have an easily-replaceable digital token with no biometric info and it’s not tied to your identity in any way, there are no such constraints.


  • Yeah it’s really not that simple. If you give someone a unique signed token that just says “whoever has this is over the age of 35” then that token becomes your unique id number that every website you share it with can use to track you. If you create a whole bunch of temporarily valid tokens for old-enough citizens any time they want some, so far you have no way top stop those getting into the hands of teenagers who want to use them to sneak into feddit.