> ## Documentation Index
> Fetch the complete documentation index at: https://docs.astral.global/llms.txt
> Use this file to discover all available pages before exploring further.

# WitnessChain

> Infrastructure-based proof-of-location via network latency triangulation

<Warning>
  **Experimental** — WitnessChain is an early-stage plugin. The interface is defined and the Verify service has experimental server-side verification logic for it; the client plugin (collecting and creating stamps) is still under development on the `develop` branch. ProofMode is the plugin that's working end to end today. We'd love to develop this and other proof-of-location plugins with partners — [get in touch](mailto:contact@astral.global).
</Warning>

# WitnessChain plugin

[WitnessChain](https://www.witnesschain.com) provides infrastructure-based proof-of-location through network latency triangulation. Independent challenger nodes measure round-trip times to a prover, then use the speed-of-light constraint to verify the prover's claimed location. This is fundamentally different from device-based proofs like ProofMode — the evidence comes from the network infrastructure, not the user's device.

## How it works

1. A **prover** registers their claimed location with WitnessChain
2. Independent **challenger** nodes send network challenges
3. Challengers measure round-trip latency and compare against speed-of-light bounds
4. If the measured latency is consistent with the claimed location, the challenge succeeds
5. Results include ECDSA-signed attestations from each challenger

This approach provides location evidence that doesn't depend on the prover's device being trustworthy — the evidence comes from independent network observers.

## Current status

The plugin is in development on the `develop` branch. The interface is fully defined:

```typescript theme={null}
class WitnessChainPlugin implements LocationProofPlugin {
  readonly name = 'witnesschain';
  readonly version = '0.1.0';
  readonly runtimes: Runtime[];
  readonly requiredCapabilities: string[];
  readonly description = 'WitnessChain proof-of-location via network latency triangulation';

  collect(options?: CollectOptions): Promise<RawSignals>;
  create(signals: RawSignals): Promise<UnsignedLocationStamp>;
  sign(stamp: UnsignedLocationStamp, signer: StampSigner): Promise<LocationStamp>;
  verify(stamp: LocationStamp): Promise<StampVerificationResult>;
}
```

### Planned capabilities

| Method      | Description                                                  | Status         |
| ----------- | ------------------------------------------------------------ | -------------- |
| `collect()` | Fetch challenge results from WitnessChain API                | In development |
| `create()`  | Parse challenge results into location stamp                  | In development |
| `sign()`    | Sign stamp with prover key                                   | In development |
| `verify()`  | Verify challenger ECDSA signatures and challenge consistency | In development |

## Challenge result structure

Each WitnessChain challenge produces:

```typescript theme={null}
interface WitnessChainChallengeResult {
  id: string;
  challenger: string;            // Ethereum address of challenger node
  claims: {                      // Prover's claimed location
    latitude: number;
    longitude: number;
    radius: number;
  };
  result: {
    challenge_succeeded: boolean;
    ping_delay: number;          // Measured latency
  };
  message: string;               // JSON-encoded challenge data
  signature: string;             // ECDSA signature from challenger
  consolidated_result: {
    KnowLoc: boolean;            // WitnessChain's location assessment
    KnowLocUncertainty: number;
    verified: boolean;
  };
}
```

## Why WitnessChain matters for multifactor proofs

WitnessChain provides a fundamentally independent evidence source:

* **Device proofs** (ProofMode) rely on the prover's hardware
* **Infrastructure proofs** (WitnessChain) rely on external network observers

When both agree, the `independence` dimension of the `CredibilityVector` reflects the corroboration from truly independent systems.

## Links

* **GitHub:** [github.com/location-proofs/plugin-witnesschain](https://github.com/location-proofs/plugin-witnesschain)
* **WitnessChain:** [witnesschain.com](https://www.witnesschain.com)