Compliance evidence that survives the audit.

// Three independent checks. Standard library only. No Akaeon code.
import crypto from 'node:crypto'

const SPKI_HEADER = Buffer.from('302a300506032b6570032100', 'hex')
const sha256 = (b) => crypto.createHash('sha256').update(b).digest()

const r = await fetch(`https://api.akaeon.com/v1/lookup?domain=${domain}`).then(x => x.json())
const o = r.optouts[0]

// 1. Ed25519 signature on the registry's canonical message
const pk = crypto.createPublicKey({
  key: Buffer.concat([SPKI_HEADER, Buffer.from(o.registry_signature.public_key, 'base64')]),
  format: 'der', type: 'spki',
})
const sigOk = crypto.verify(null,
  Buffer.from(o.registry_signature.canonical_message, 'utf8'),
  pk,
  Buffer.from(o.registry_signature.signature, 'base64'))

// 2. Merkle inclusion proof reconstructs the claimed root
let c = Buffer.from(o.merkle_inclusion.leaf_hash, 'hex'), i = o.merkle_inclusion.leaf_index
for (const s of o.merkle_inclusion.merkle_proof) {
  const [l, ri] = (i & 1) === 0 ? [c, Buffer.from(s, 'hex')] : [Buffer.from(s, 'hex'), c]
  c = sha256(Buffer.concat([Buffer.from([0x01]), l, ri]))
  i >>= 1
}
const merkleOk = c.toString('hex') === o.merkle_inclusion.merkle_root

// 3. Arweave-anchored batch payload contains the same root
const ar = await fetch(o.merkle_inclusion.arweave_url).then(x => x.json())
const anchorOk = ar.merkle_root_sha256_hex === o.merkle_inclusion.merkle_root

console.log({ sigOk, merkleOk, anchorOk })