@emilia-protocol/verify

Zero-dependency offline verification for EP trust receipts.

Verify Ed25519-signed trust receipts, Merkle anchor proofs, and commitment proofs using only Node.js built-in crypto. No EP infrastructure required. No API key. No account. Just math.

This is the core primitive that makes EP a protocol, not an API.

Install

npm install @emilia-protocol/verify

Quick Start

import { verifyReceipt } from '@emilia-protocol/verify';

// Load a receipt document (EP-RECEIPT-v1 format)
const receipt = JSON.parse(fs.readFileSync('receipt.json', 'utf8'));

// Get the signer's public key (from /.well-known/ep-keys.json)
const publicKey = 'MFYwEAYHKoZIzj0CAQYFK4EEAA...'; // base64url SPKI DER

const result = verifyReceipt(receipt, publicKey);
console.log(result);
// { valid: true, checks: { version: true, signature: true, anchor: null } }

API

verifyReceipt(doc, publicKeyBase64url)

Verify an EP-RECEIPT-v1 document. Performs three independent checks:

1. Version — Document format is EP-RECEIPT-v1
2. Signature — Ed25519 signature over canonical payload
3. Anchor (if present) — Merkle proof reconstructs claimed root

Returns { valid, checks, error? }.

verifyMerkleAnchor(leafHash, proof, expectedRoot)

Verify a Merkle inclusion proof. The root can be independently checked on Base L2 via Basescan.

Returns boolean.

verifyCommitmentProof(proof, publicKeyBase64url)

Verify an EP-PROOF-v1 commitment proof. Checks expiry and signature.

Returns { valid, claim, error? }.

verifyReceiptBundle(bundle, publicKeyBase64url)

Verify all receipts in an EP-BUNDLE-v1 document.

Returns { valid, total, verified, failed }.

Design Principles

• Zero dependencies — Only node:crypto. No supply chain risk.
• Offline-first — No network calls. No EP server needed.
• Deterministic — Canonical JSON serialization for reproducible signatures.
• Auditable — Single file, ~170 lines. Read the entire thing in 5 minutes.

How It Works

Receipt Document (EP-RECEIPT-v1)
├── payload (canonical JSON)
├── signature
│   ├── algorithm: "Ed25519"
│   ├── signer: "ep_entity_..."
│   └── value: base64url signature
└── anchor (optional)
    ├── leaf_hash: SHA-256 of receipt
    ├── merkle_proof: [{hash, position}, ...]
    ├── merkle_root: root hash
    └── chain: "base-sepolia"

Verification:
1. Canonicalize payload → sorted-key JSON
2. Verify Ed25519(canonical_payload, signature, public_key)
3. If anchor: reconstruct Merkle root from proof, compare

Getting Public Keys

Signer public keys are discoverable at /.well-known/ep-keys.json on any EP operator:

curl https://ep.example.com/.well-known/ep-keys.json

License

Apache-2.0