

I’m not 100% deep on the crypto, but my understanding is they use blind signatures (which have been around for a long time) to do their issuing. If you’re unfamiliar, these are kinda like an envelope with a hole cut in it, so you can put a document in it with a hidden unique key, and they can see some info through the hole, and can stamp their signature through the hole to validate that it’s legit without knowing the hidden info.
Then the user can remove it from the envelope (unblind) and now have a certified valid coin without the issuer knowing which coin is theirs.
So in the context of an ATM, the ATM wouldn’t “issue” coins, it would be given a request for coins from your wallet, it would certify the validity of that request, and then give your wallet back that certification in such a way that the wallet could unblind it and have the anonymous secret. So ultimately your wallet is the one that’s in charge of producing the unique parts.
It seems there’s also a system for making sure you don’t produce bad transactions by asking you to generate N, promping you to unwrap a bunch of them to prove there’s nothing weird about them, and then signing one of the remaining ones under the assumption it’s also legit. At least it sounds like it, but I’m even less familiar with that part. But even if you did spoof someone else’s secrets… it doesn’t allow you to steal their money I don’t think… because in order to have your transaction validated in the first place you had to truly give the ATM your money… so you could I guess pay $10 to screw over your friend for $10 because it’ll look like they spent money they didn’t… but you still spent $10… so it’s less like stealing their money and more like paying to throw their wallet off a bridge? You don’t gain anything, but they lose something? Maybe there’s another exploit I don’t know about in the like “renewal” or “refund” or “transfer” protocols that make that more important.
Anyway, I’m still not a Taler fan, but in this case I think it’s possible to do what they claim. Now, if the bank or ATM or whatever asks for ID or an account to use their services, they could track that you withdrew money, and how much. That’s data they can collect. The anonymous buyer part just means they can’t tie the coin they issued you to a spent deposit they receive later. So they know you got $10 out, and they can assume you probably spent it, but they can’t know what you spent it on.
There’s an app I’ve never used but heard of: https://adresilo.com/
I think the way it works is that it queries Google’s API for locations, proxies through them, but it can’t show them on a map due to Terms of Service, but it can provide links that will then open in any map app of your choice.
The app is open source, but the DB is obviously Google. So it’s trying to blur that line of providing Open Source functionality, and using Open Source maps, with the practicality of “Google has all the stuff” UX problem.
At least I think…