zero knowledge prove device location within a circle
a signed app knows gets the device location
zkp with
public inputs:
- coordinates on a sphere (circle center =: C)
- radius (r)
private inputs: own coordinates on a sphere (location =: l)
circom circuit estimates spherical distance between the C and l =: d(C,l)
zkp <=> d(C,l) <= r
use case: social apps to prove location without compromising privacy
vs https://www.stratumn.com/en/blog/zero-knowledge-proof-of-location, we zkp that location is within an arbitrary circle, not amongst "a list of authorized areas"