I really like Andy Birrells "micro-cents" which exploited the fact you could not easily reverse an MD5 hash so you one could cheaply do high confidence low value transactions at speed. Another idea that never got anywhere sadly.
ZKP ID cards and ZKP currency are both interesting things from the 90's I'd love to see in real life. Imagine I could pay you phone to phone with no network level of capability using a currency that couldn't be double spent. That was the promise of digicash. The government hated it :-). It was just like cash currency in that serial numbers could let you track the bank it left, and the bank it came back in to, but you couldn't track anywhere it had been between those two points.
Fun times. I'll have to see if some of my ZKP ideas can be built on top of this tech now.
Do you still feel that way knowing that it introduces a hard requirement for all users to have their private data managed by one of Apple, Google, or Microsoft[1]? I want to be excited about this, and about Passkeys, but the people working in this space keep fumbling this ball :(
[1] "Using the MDOC requires a signature from a hardware security key in the phone" >>44458417
> To be very honest here, you risk having KeePassXC blocked by relying parties
Even if the bigtechs don't "officially" make the passkey standards require bigtech involvement, it seems very likely to me that conservative businesses like banks will only accept bigtech implementations. And then you're sunk.
Similarly, look at how OpenID turned into "Sign in with AppleGooFaceSoft".
This ZKP+hardware secure element stuff seems even worse, because how are you going to make it work on old hardware, or with free software, or with open devices?