> ## Documentation Index > Fetch the complete documentation index at: https://astral-6ef288be-docs-policy-evaluation-framing.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Proof-of-Location Systems > Strategies and technologies for producing location evidence **Research Preview** — APIs may change. [GitHub](https://github.com/AstralProtocol) # 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](/concepts/location-stamps) comes from a proof-of-location system, wrapped in a [location proof plugin](/concepts/location-proof-structure#location-proof-plugins). 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](https://www.gsc-europa.eu/galileo/services/galileo-open-service-navigation-message-authentication-osnma) — 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](/plugins/overview). **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: 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). 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. The Verify service also includes experimental stamp-verification logic for `gpsd`, `geoclue`, `wifi-mls`, and `ip-geolocation`. The [Mock plugin](/plugins/mock) 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](mailto:contact@astral.global). ## 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](/plugins/custom) that implements the standard interface. Evidence from a single proof-of-location system *** **See also:** * [Plugins overview](/plugins/overview) — the full plugin ecosystem * [ProofMode plugin](/plugins/proofmode) — device attestation details * [WitnessChain plugin](/plugins/witnesschain) — network verification details