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. // callout: Location verification is ubiquitous online, but it is usually ad hoc or unverifiable. Things ranging from GeoIP lookups, scanning a QR code, inputting a passphrase, checking in with an event host, even submitting a bank statement as proof-of-address… the Location Proof Framework is intended to make these different techniques more transparent and legible …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, affadavits | 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 the Astral Protocol is launching with limited support for these proof-of-location systems through location proof plugins:ProofMode
Device attestation + sensor fusion. Uses iOS Secure Enclave and Android hardware keystore to attest to device sensor readings (GPS, Wi-Fi, cellular, magnetometer). Trust comes from device hardware integrity.
WitnessChain
Infrastructure verification. Uses UDP latency triangulation across a distributed challenger network. Trust comes from the speed of light — you can’t fake being close to multiple geographically distributed nodes simultaneously.
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