{
  "ok": true,
  "challenge": {
    "id": "d61e448e9aa1194b3f1f8a11",
    "nonce": "4f01ffb32f793b9fc68a1fed50f42f9efdc188ff",
    "issuedAt": "2026-05-29T19:22:42.037Z",
    "expiresAt": "2026-05-29T19:32:42.037Z",
    "signature": "5bccd7793af753007ee8bc3b1129eb3d422f2d948d77248466febb407f90039c",
    "algorithm": "HMAC-SHA256",
    "version": "v1",
    "payloadSignatureSpec": "sha256_hex(challenge.id + ':' + challenge.nonce + ':' + canonical_json(payload))"
  }
}