@synoi/verify

Offline Ed25519 verifier for SynOI Decision Receipts.

Anyone with a receipt ID — your auditor, your counterparty, your regulator — can cryptographically prove the decision was real, was made by the gateway they think it was, and hasn't been tampered with. Without contacting SynOI.

npx @synoi/verify rcpt_abc_123

  Gateway     : https://gateway.synoi.systems
  Receipt ID  : rcpt_abc_123
  Algorithm   : Ed25519
  Signer key  : key_2026_05_18
  Canonical   : {"action_class":"B","decision":"allow","oid_hex":"...","receipt_id":"rcpt_abc_123","recorded_at":1747584000000,"risk_level":"low","tenant_id":"founder"}

  ✓ VERIFIED — signature is valid; receipt has not been tampered with.

Exit code is 0 on a verified signature, 1 if invalid, 2 on usage / network errors.

Verify a remote gateway

npx @synoi/verify rcpt_abc_123 --gateway https://gateway.synoi.systems

Programmatic use

import { fetchAndVerify } from '@synoi/verify'

const result = await fetchAndVerify('rcpt_abc_123', 'https://gateway.synoi.systems')
if (!result.valid) {
  throw new Error(`Receipt rejected: ${result.reason}`)
}
console.log(result.canonical_payload)

For fully offline use (no fetch), import the pure verifier:

import { verifyReceiptSignature } from '@synoi/verify'

const result = verifyReceiptSignature(receiptJson, signatureHex, publicKeyPem)

What's being verified

The signature covers exactly seven canonical fields, alphabetically sorted, JSON-stringified with default separators:

action_class, decision, oid_hex, receipt_id, recorded_at, risk_level, tenant_id

Any other fields on the receipt (latency_ms, intent_id, action_type, etc.) are operational metadata and not part of the signature. Tampering with them won't fail verification — by design.

Algorithm: Ed25519 · Signature encoding: 128 hex chars (64 raw bytes) · Public key: PEM SPKI, available at GET <gateway>/verify/pubkey.

Why offline matters

The promise of the SynOI Decision Receipt is "verifiable by anyone, without SynOI infrastructure." This package is the proof artifact: once you have the receipt + the gateway's public key (which the gateway publishes openly), no further contact with SynOI or the gateway is needed. You can verify a receipt from five years ago on an airplane.

If the gateway disappears tomorrow, every receipt that has ever been issued is still cryptographically verifiable — as long as someone preserved the public key.