Research Preview — APIs may change. GitHub
Proof-of-Location Systems
A proof-of-location system is any system that produces evidence about physical location. These systems are the foundation of location proofs — each location stamp comes from a proof-of-location system, wrapped in a location proof plugin.Location verification is already everywhere online, but it’s usually ad hoc and hard to check: GeoIP lookups, scanning a QR code, entering a passphrase, checking in with an event host, even submitting a bank statement as proof of address. The Location Proof framework is an attempt to make these techniques more transparent and legible — not to replace them.
Categories of proof-of-location systems
Proof-of-location systems span a wide range of approaches, from hardware-based measurement to social attestation:| Category | Mechanism | Example | Strengths | Limitations |
|---|---|---|---|---|
| Near-field machine | Physical proximity verification via short-range signals | RFID, NFC, Bluetooth beacons | Hard to forge without physical presence | Short range; requires infrastructure |
| Network machine | Position derived from network measurements | Time of Flight, TDOA, latency triangulation | Independent of device; based on physics | Requires distributed infrastructure |
| Sensor data | Location inferred from environmental readings | Magnetometer signatures, image/audio analysis | Rich contextual evidence | Computationally expensive to verify, difficult to detect generated sensor data |
| Delegated | Trusted third party attests to location | Notarized presence, institutional witness | Leverages existing trust relationships | Only as trustworthy as the delegate |
| Social | Peer confirmations of co-location | Mutual attestation, group check-in | Distributed trust; no infrastructure needed | Collusion risk |
| Authority-based | Authorized entity confirms location | Government agency, licensed surveyor | High institutional trust | Centralized; requires authority access |
| Legal | Location established through legal process | Court records, notarized documents, affidavits | Strong evidentiary weight, legal liability of fraud | Slow; expensive; not real-time |
Current state of the field
Honesty matters here: few “hard” proof-of-location systems exist at scale today, and even fewer are decentralized. Most deployed location infrastructure (GPS, Wi-Fi positioning, cell tower triangulation) was designed for navigation, not proof. These systems tell you where you are but don’t produce cryptographically verifiable evidence that you were there. The proof-of-location systems that do exist with meaningful cryptographic properties — hardware attestation, network latency triangulation, secure enclave readings, Galileo’s OSNMA authentication feature — are still maturing. Each has real limitations and known attack vectors. That said, significant value comes from “softer” proof-of-location systems too. Even a single device attestation with sensor readings, while not unbreakable, raises the cost of forgery substantially compared to self-reported GPS. And combining multiple independent sources — even individually weak ones — creates meaningful assurance through cross-correlation. Our vision is to build a community ecosystem of location proof plugins, and over time enhance our capability to create location proofs further and further up the certainty spectrum.Available plugins
v0 of Astral connects to proof-of-location systems through location proof plugins. ProofMode is working today — its stamps can be verified end to end. The other plugins are experimental, with interfaces defined and early verification logic in place. The two highlighted below are the documented examples:ProofMode — implemented
Device attestation + sensor fusion. Uses iOS Secure Enclave and Android hardware keystore to attest to device sensor readings (GPS, Wi-Fi, cellular, magnetometer). Trust derives from device hardware integrity. This is the one proof-of-location plugin available today (alpha).
WitnessChain — experimental
Infrastructure verification. The design uses UDP latency triangulation across a distributed challenger network, where trust derives from the speed of light — you can’t fake being close to many geographically distributed nodes at once. The interface is defined and an experimental server-side verification logic exists; it’s not production yet.
gpsd, geoclue, wifi-mls, and ip-geolocation. The Mock plugin is available for development and testing on the client.
ProofMode is working today; the others are experimental, with interfaces defined and early verification logic in place. We’re actively interested in developing new proof-of-location plugins with partners — if you work on a proof-of-location system, get in touch.
Building new plugins
The location proof plugin interface is extensible by design. If you have a proof-of-location system that isn’t covered by existing plugins, you can build a custom plugin that implements the standard interface.Next: Location stamps
Evidence from a single proof-of-location system
See also:
- Plugins overview — the full plugin ecosystem
- ProofMode plugin — device attestation details
- WitnessChain plugin — network verification details