Research Preview — Additional schema UIDs will be published as they are deployed.

EAS Schemas

Astral Location Services uses the Ethereum Attestation Service (EAS) for all attestations. This page documents the schema definitions.

Location Attestation Schema

Used for storing spatial data (points, polygons, routes).

bytes geometry, string geometryType, string srs, bytes properties

Field	Type	Description
`geometry`	bytes	Encoded GeoJSON geometry
`geometryType`	string	”Point”, “Polygon”, “LineString”, etc.
`srs`	string	Spatial reference system (default: “EPSG:4326”)
`properties`	bytes	JSON-encoded metadata

Policy Attestation Schemas

Output schemas for geospatial computations.

BooleanPolicyAttestation

For predicate operations (contains, within, intersects).

bool result, bytes32[] inputRefs, uint64 timestamp, string operation

Field	Type	Description
`result`	bool	The boolean computation result
`inputRefs`	bytes32[]	References to inputs (UIDs or hashes)
`timestamp`	uint64	Unix timestamp of computation
`operation`	string	Operation with parameters (e.g., “within:50000”, “contains”) — the `within` radius is encoded in centimeters; see the note below

NumericPolicyAttestation

For measurement operations (distance, length, area).

uint256 result, string units, bytes32[] inputRefs, uint64 timestamp, string operation

Field	Type	Description
`result`	uint256	Scaled integer result (centimeters or cm²)
`units`	string	Base unit (“meters” or “square_meters”)
`inputRefs`	bytes32[]	References to inputs
`timestamp`	uint64	Unix timestamp of computation
`operation`	string	Operation with parameters (e.g., “distance”, “area”)

GeometryPolicyAttestation (Future)

For transformation operations (buffer, centroid, union).

bytes geometry, string geometryType, bytes32[] inputRefs, uint64 timestamp, string operation

Operation strings include parameters — For example, the within operation returns "within:50000" (radius in centimeters), not just "within". Resolver contracts should use prefix matching when validating operations.

Default Schema UIDs

Astral provides pre-registered schemas without resolver contracts for general use. Use these when you don’t need custom validation logic.

Base Sepolia (84532)

Schema	UID	Use For
BooleanPolicyAttestation	`0x4958625091a773dcfb37a1c33099a378f32a975a7fb61f33d53c4be7589898f5`	`contains`, `within`, `intersects`
NumericPolicyAttestation	Register your own	`distance`, `length`, `area`
Location	Register your own	Location attestations

The BooleanPolicyAttestation schema UID above is the default used by the staging API. For production use or custom resolver logic, register your own schema.

Custom schemas: If you need a resolver contract for custom validation (like the Location-Gated NFT), register your own schema with the same field types. The schema UID will be different, but the data encoding is identical.

Input References

The inputRefs array contains a bytes32 for each input:

Input Type	Reference
Onchain attestation	The UID
Offchain attestation	The UID
Raw GeoJSON	`keccak256(abi.encode(geojson))`

This enables verification that specific inputs were used:

(bool result, bytes32[] memory inputRefs, , ) = abi.decode(...);

// Verify expected landmark was checked
require(inputRefs[1] == EXPECTED_LANDMARK_UID, "Wrong location");

Result Scaling

Numeric results are stored as scaled integers:

Measurement	Storage	Conversion
Distance	centimeters	`meters = result / 100`
Length	centimeters	`meters = result / 100`
Area	square centimeters	`m² = result / 10000`

// In your resolver
(uint256 resultCm, , , , ) = abi.decode(...);
uint256 meters = resultCm / 100;

Decoding in Solidity

Boolean Policy

function decodeBooleanPolicy(bytes memory data) public pure returns (
    bool result,
    bytes32[] memory inputRefs,
    uint64 timestamp,
    string memory operation
) {
    return abi.decode(data, (bool, bytes32[], uint64, string));
}

Numeric Policy

function decodeNumericPolicy(bytes memory data) public pure returns (
    uint256 result,
    string memory units,
    bytes32[] memory inputRefs,
    uint64 timestamp,
    string memory operation
) {
    return abi.decode(data, (uint256, string, bytes32[], uint64, string));
}

Schema Registry

Schemas are registered in the EAS SchemaRegistry. When deploying your resolver:

import { SchemaRegistry } from '@ethereum-attestation-service/eas-sdk';

const registry = new SchemaRegistry(REGISTRY_ADDRESS);

// Register schema with your resolver
// IMPORTANT: Use revocable: true - Astral signs with revocable=true
const tx = await registry.connect(signer).register({
  schema: "bool result,bytes32[] inputRefs,uint64 timestamp,string operation",
  resolverAddress: yourResolver.address,
  revocable: true
});

const receipt = await tx.wait();
const schemaUID = receipt.logs[0].args.uid;

Security

Threat model, known limitations, and responsible disclosure

Getting Started

Core Concepts

Guides

Use Cases

Integrations

Trust Model

Resources

Schemas

EAS Schemas

Location Attestation Schema

Policy Attestation Schemas

BooleanPolicyAttestation

NumericPolicyAttestation

GeometryPolicyAttestation (Future)

Default Schema UIDs

Base Sepolia (84532)

Input References

Result Scaling

Decoding in Solidity

Boolean Policy

Numeric Policy

Schema Registry

Security

​EAS Schemas

​Location Attestation Schema

​Policy Attestation Schemas

​BooleanPolicyAttestation

​NumericPolicyAttestation

​GeometryPolicyAttestation (Future)

​Default Schema UIDs

​Base Sepolia (84532)

​Input References

​Result Scaling

​Decoding in Solidity

​Boolean Policy

​Numeric Policy

​Schema Registry

Security

EAS Schemas

Location Attestation Schema

Policy Attestation Schemas

BooleanPolicyAttestation

NumericPolicyAttestation

GeometryPolicyAttestation (Future)

Default Schema UIDs

Base Sepolia (84532)

Input References

Result Scaling

Decoding in Solidity

Boolean Policy

Numeric Policy

Schema Registry