Very related work

[dbosk]

• Proof of Witness Presence: Blockchain Consensus for Augmented Democracy in Smart Cities was published on arXiv in June 2019 (updated October 2019).
• PASPORT: A Secure and Private Location Proof Generation and Verification Framework
• SPARSE: Privacy-Aware and Collusion Resistant Location Proof Generation and Verification solves collusion in crowded scenarios [must be verified how].
• Our DB-Schnorr paper in CANS'20.

[dbosk]

PASPORT

The verifier is trusted and also known in advance, like a location-based service. That doesn't work with universal verifiability.

The verifier chooses the subset of witnesses that can vouch for a prover. Which makes it an interactive protocol. And the verifier must know which witnesses are on location in advance. The verifier must trust the witness to be honest about the location, this is not addressed by the paper.

[dbosk]

SPARSE

Doesn't use distance bounding.

It's very similar to PASPORT otherwise.

[dbosk]

Witness presence

Witness presence means witness for some data about something in the physical world. For instance, citizens can witness about bicyclists speeding on pedestrian sidewalks.

The paper gives a nice overview of available technologies. Its focus is on merging these technologies to form an augmented democracy.

It provides an overview of blockchain technologies for location proofs. Never mentions distance bounding though, just "limited range" bluetooth or wifi communication or mobile networks. It mentions Platin (platin.io?) as one example.

It also mentions "collaborative social challenges" to complement the location proofs.

Its main point is to construct collective awareness, putting verified data (witnessed by people) on the blockchain.