Zero-knowledge proof of location
Proof of location is a way for a device to prove where it was without revealing where it is: location verification without GPS, built on mesh adjacency attestations and zero-knowledge proofs.
What is proof of location?
Location claims are easy to fake. GPS coordinates are self-reported by the device, and GPS itself can be spoofed with commodity hardware. Any workflow that pays, credits, or authorizes based on "I was there" needs a proof, not a report.
Proof of location makes the claim verifiable: a device gathers evidence that it was at a place and time, typically attestations from other radios that physically saw it, and packages that evidence so a third party can check it later.
The zero-knowledge part addresses the privacy cost. A ZK proof lets the device prove a statement about its location, "inside this zone during this window", without disclosing the raw trajectory or the identities of its witnesses.
Diagram: zero-knowledge proof of location without GPS, where nearby mesh devices witness a phone over Bluetooth LE, sign adjacency attestations with Ed25519 keys, and the phone produces a ZK proof of presence in a zone without disclosing its trajectory or witnesses.
Presence, witnessed and then sealed: three independent devices sign time-boxed attestations that they physically exchanged radio traffic with scout-12 inside zone-7. The phone folds that evidence into a zero-knowledge proof, and the verifier learns exactly one thing: the statement is true.
How Offline Protocol implements it
The mesh is the witness network. Physical radio contact is the evidence, and OfflineID signs it:
Nearby nodes sign time-boxed statements that they exchanged radio traffic with the device. BLE and WiFi Direct range physically bound the claim.
Each attestation is signed by the witness's OfflineID, making the evidence attributable and tamper-evident without a server.
The device proves the statement it needs, presence in a zone, during a window, without revealing the raw attestations, its full path, or witness identities.
Evidence is gathered with zero connectivity and verified whenever the proof reaches a verifier, minutes or weeks later.
GPS-independent by design: the proof survives jamming and spoofing because it never relied on positioning signals.
Proof of presence: what the mesh actually attests
Proof of presence is a narrower and more honest claim than a coordinate. The mesh does not measure where a device is; it records which other devices physically exchanged radio traffic with it, and when. Because BLE and WiFi Direct have hard physical range limits, a signed adjacency record is a statement that two radios were within tens to hundreds of meters of each other during a specific window.
Stack enough of those records from independent witnesses and you get a location claim that is hard to fake and easy to check. Each witness signs with its OfflineID, so the evidence carries identity history, and the whole exchange rides the same mesh transport the devices already use to communicate.
The zero-knowledge layer then decides what a verifier sees: the proven statement, such as presence at a delivery point during a shift, and nothing else. For workflows like chain-of-custody in logistics, that separation between evidence and disclosure is the feature.
Verifying on-chain: the operator network
For workflows that settle on-chain, location proofs verify through a decentralized operator network rather than a single geolocation service. Geographically distributed operators independently measure and validate a claim, sign their results, and post them on-chain, producing an immutable record no single party controls.
The network is economically accountable: operators stake through EigenLayer, misbehavior is slashable, and honest validation earns rewards. Collusion has to beat both the cryptography and the economics, and the cost of doing so rises with every independent operator in the set.
This unlocks location-aware applications with no trusted middleman: rewards distributed only to users who can prove they were at a place, region-scoped access rules, and verifiable proof of presence at real-world events, each consuming the proof without ever seeing a raw trajectory.
What makes spoofing expensive
- Speed of light
- Round-trip latency is bounded by the speed of light in fiber, so a device claiming one city while responding from another produces timing that is physically impossible, not just suspicious.
- Tolerance margins
- Configurable margins absorb ordinary network jitter without opening the door to false claims, tuned per use case by the application consuming the proof.
- Independent witnesses
- No single operator's word decides a claim: multiple geographically distributed verifiers must independently agree, and their signed results are permanent.
- Economic stake
- An operator caught validating impossible claims loses stake. Faking a location means beating the speed of light, a quorum of witnesses, and the economics at once.
Where it applies
- Aid and field data
- Aid distribution and field data collection with verifiable presence.
- Autonomous missions
- Mission verification for autonomous systems in GPS-denied environments.
- Venues
- Attendance and access workflows at real-world events.
Proof of location FAQ
How can you verify location without GPS?
Through radio adjacency: nearby devices sign time-boxed attestations that they physically exchanged traffic with the claimant over BLE or WiFi Direct. Radio range bounds the claim, so the evidence works indoors, underground, and anywhere GPS is jammed or absent.
Why is this stronger than GPS?
GPS is a self-reported reading of a spoofable signal. Adjacency attestation requires other physical radios to have actually seen the device, signed with keys the claimant does not control.
Can witnesses collude to fake a location?
Collusion cost rises with witness count and diversity. Verifiers set the evidence threshold per use case, and witness identities carry OfflineID history.
What does the verifier learn?
Only the proven statement, such as presence in a declared zone during a window. The raw trajectory and witness set stay private.
Is this available today?
Proof of location is an active platform capability built on shipped primitives, OfflineID and the DORS mesh. Contact us to discuss fit for your workflow.
What keeps verifiers honest?
The on-chain verification path uses a decentralized operator network with economic accountability: operators independently validate claims, results are signed and posted on-chain, and misbehaving operators can be penalized through EigenLayer slashing while honest ones earn rewards.
Do the offline and on-chain paths work together?
Yes. Evidence gathered offline is held on the device and submitted for verification when a link appears, so a claim captured in a dead zone can still settle as an on-chain proof hours or days later.
