what’s the state of the art? I always imagined you could just have some random number generator sunk into concrete somewhere and do kind of like the authenticator apps do: turn the crank on the RNG to produce the next key. except instead of having 30 seconds to type it in, your phone would have like .3 milliseconds to communicate that to the geo-beacon to prove that you’re nearby, then the geobeacon can sign your attestation and you can use that proof however you want