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EAS (Ethereum Attestation Service)

The EASHelper module provides integration with Ethereum Attestation Service for delivery proof attestations.

Overview​

EASHelper enables:

  • Creating on-chain attestations for delivery proofs
  • Verifying attestation authenticity
  • Revoking attestations if needed
  • Replay attack prevention

Configuration​

// Level 2: Advanced API - Direct protocol control
interface EASConfig {
  contractAddress: string;        // EAS contract address
  deliveryProofSchemaId: string;  // Schema UID for delivery proofs
}

Network Addresses:

NetworkEAS ContractSchema Registry
Base Sepolia0x42000000000000000000000000000000000000210x4200000000000000000000000000000000000020
Base Mainnet0x42000000000000000000000000000000000000210x4200000000000000000000000000000000000020

Methods​

attestDeliveryProof()​

Create an on-chain attestation for a delivery proof.

// Level 2: Advanced API - Direct protocol control
import { ProofGenerator, EASHelper } from '@agirails/sdk';

// Generate delivery proof
const proofGenerator = new ProofGenerator();
const proof = proofGenerator.generateDeliveryProof({
  txId,
  deliverable: 'Result content here',
  deliveryUrl: 'ipfs://Qm...',
});

// Create attestation
const eas = new EASHelper(signer, {
  contractAddress: EAS_ADDRESS,
  deliveryProofSchemaId: SCHEMA_ID,
});

const attestation = await eas.attestDeliveryProof(
  proof,
  requesterAddress, // Recipient of attestation
  {
    expirationTime: 0, // No expiration (0 = forever)
    revocable: true,
  }
);

console.log('Attestation UID:', attestation.uid);
console.log('Transaction hash:', attestation.transactionHash);

// Anchor to kernel
await kernel.anchorAttestation(txId, attestation.uid);

Parameters:

ParameterTypeDescription
proofDeliveryProofProof from ProofGenerator
recipientstringWho receives the attestation
options.expirationTimenumber?Expiry timestamp (0 = never)
options.revocableboolean?Can be revoked (default: true)

Returns:

interface AttestationResponse {
  uid: string;           // Attestation UID (bytes32)
  transactionHash: string;  // Blockchain tx hash
}

verifyAttestation()​

Verify an attestation's validity.

// Level 2: Advanced API - Direct protocol control
const isValid = await eas.verifyAttestation(attestationUID, {
  expectedTxId: txId,
  expectedProvider: providerAddress,
});

if (isValid) {
  console.log('Attestation verified!');
} else {
  console.log('Invalid attestation');
}

Verification checks:

  • Attestation exists on-chain
  • Not revoked
  • Not expired
  • Schema matches delivery proof schema
  • Content matches expected values

revokeAttestation()​

Revoke a previously issued attestation.

// Level 2: Advanced API - Direct protocol control
const txHash = await eas.revokeAttestation(attestationUID);
console.log('Revocation tx:', txHash);

Use cases:

  • Dispute resolution (invalidate delivery)
  • Error correction
  • Provider requested revocation

getAttestation()​

Fetch attestation details from chain.

// Level 2: Advanced API - Direct protocol control
const attestation = await eas.getAttestation(attestationUID);

console.log('Schema:', attestation.schema);
console.log('Recipient:', attestation.recipient);
console.log('Attester:', attestation.attester);
console.log('Revoked:', attestation.revoked);
console.log('Time:', new Date(attestation.time * 1000));

Delivery Proof Schema​

The AGIRAILS delivery proof schema:

bytes32 txId          // Transaction ID
bytes32 contentHash   // Keccak256 of deliverable
uint256 timestamp     // Delivery timestamp
string deliveryUrl    // IPFS/Arweave URL (optional)
uint256 size          // Content size in bytes
string mimeType       // Content MIME type

Security Features​

Replay Attack Prevention​

EASHelper tracks used attestations to prevent replay:

// Level 2: Advanced API - Direct protocol control
import { FileBasedUsedAttestationTracker } from '@agirails/sdk';

// Use file-based tracker for persistence
const tracker = new FileBasedUsedAttestationTracker('.actp/attestations');

const eas = new EASHelper(signer, config, tracker);

Warning: Default in-memory tracker loses state on restart. Use file-based tracker in production.

Schema Validation​

Constructor validates schema UID format:

  • Must be bytes32 hex string (0x + 64 chars)
  • Cannot be zero bytes32

Example: Complete Delivery Flow​

// Level 2: Advanced API - Direct protocol control
import {
  ACTPClient,
  ProofGenerator,
  EASHelper,
  State,
} from '@agirails/sdk';

async function deliverWithAttestation(txId: string, result: string) {
  const client = await ACTPClient.create({
    mode: 'testnet',
    privateKey: process.env.PRIVATE_KEY!,
  });

  // 1. Generate proof
  const proofGen = new ProofGenerator();
  const proof = proofGen.generateDeliveryProof({
    txId,
    deliverable: result,
    metadata: {
      mimeType: 'application/json',
    },
  });

  // 2. Create EAS attestation
  const eas = new EASHelper(client.signer, {
    contractAddress: EAS_ADDRESS,
    deliveryProofSchemaId: SCHEMA_ID,
  });

  const tx = await client.advanced.getTransaction(txId);
  const attestation = await eas.attestDeliveryProof(proof, tx.requester);

  console.log('Created attestation:', attestation.uid);

  // 3. Anchor attestation to transaction
  await client.advanced.anchorAttestation(txId, attestation.uid);

  // 4. Transition to DELIVERED
  await client.advanced.transitionState(txId, State.DELIVERED);

  console.log('Delivery complete with on-chain proof!');
}

Next Steps​

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