Okta・Auth0の本人確認（IDV）連携

{
  "id_token": {
    "verified_claims": [
      {
        "verification": {
          "trust_framework": { "value": "IDV-DELEGATED" },
          "assurance_level": { "value": "VERIFIED" }
        },
        "claims": {
          "given_name": { "value": "Lucas", "fuzzy": true },
          "family_name": { "value": "Fraggioli", "fuzzy": true }
        }
      }
    ]
  }
}

{
  "iss": "https://apx.didit.me/auth/idv",
  "sub": "eea9c5ca-63e6-437b-8e94-131c33f5dce8",
  "aud": "<your client id>",
  "nonce": "<your nonce>",
  "verified_claims": [
    {
      "verification": {
        "trust_framework": "IDV-DELEGATED",
        "assurance_level": "VERIFIED",
        "time": "2026-07-09T11:59:33Z",
        "verification_process": "eea9c5ca-63e6-437b-8e94-131c33f5dce8"
      },
      "claims": {
        "given_name": { "value": "Lucas Agustin", "fuzzy": true },
        "family_name": { "value": "Fraggioli", "fuzzy": true }
      }
    }
  ]
}

const crypto = require("crypto");

// Correlate each login's PKCE verifier with its own transaction so a retried
// or overlapping login can't overwrite it (which would fail the token exchange).
const txKey = (event) =>
  event.transaction?.id || event.request?.query?.state || "default";

const basicAuth = (event) =>
  Buffer.from(
    `${event.secrets.DIDIT_CLIENT_ID}:${event.secrets.DIDIT_CLIENT_SECRET}`
  ).toString("base64");

exports.onExecutePostLogin = async (event, api) => {
  if (event.user.app_metadata?.idv_status === "verified") return;

  const verifier = crypto.randomBytes(48).toString("base64url");
  const challenge = crypto.createHash("sha256").update(verifier).digest("base64url");

  const pending = { ...event.user.app_metadata?.idv_pkce };
  pending[txKey(event)] = verifier;
  api.user.setAppMetadata("idv_pkce", pending);

  const params = {
    response_type: "code",
    client_id: event.secrets.DIDIT_CLIENT_ID,
    redirect_uri: `https://${event.request.hostname}/continue`,
    scope: "openid profile identity_assurance",
    code_challenge: challenge,
    code_challenge_method: "S256",
    login_hint: event.user.email ?? "",
  };

  // Ask Didit to match the scanned document against this user's known name, so an
  // approved session for a different person can't mark this account verified.
  if (event.user.given_name && event.user.family_name) {
    params.claims = JSON.stringify({
      id_token: {
        verified_claims: [
          {
            verification: { trust_framework: { value: "IDV-DELEGATED" } },
            claims: {
              given_name: { value: event.user.given_name, fuzzy: true },
              family_name: { value: event.user.family_name, fuzzy: true },
            },
          },
        ],
      },
    });
  }

  const res = await fetch(`${event.secrets.DIDIT_IDV_BASE}/par`, {
    method: "POST",
    headers: {
      "Content-Type": "application/x-www-form-urlencoded",
      Authorization: `Basic ${basicAuth(event)}`,
    },
    body: new URLSearchParams(params).toString(),
  });
  if (!res.ok) return api.access.deny("Identity verification is unavailable.");

  const { request_uri } = await res.json();
  api.redirect.sendUserTo(`${event.secrets.DIDIT_IDV_BASE}/authorize`, {
    query: { request_uri, client_id: event.secrets.DIDIT_CLIENT_ID },
  });
};

exports.onContinuePostLogin = async (event, api) => {
  const code = event.request.query.code;
  const pending = { ...event.user.app_metadata?.idv_pkce };
  const key = txKey(event);
  const verifier = pending[key];

  // Consume the verifier so it can't be reused.
  if (key in pending) {
    delete pending[key];
    api.user.setAppMetadata("idv_pkce", pending);
  }
  if (!code || !verifier) return api.access.deny("Identity verification was not completed.");

  const res = await fetch(`${event.secrets.DIDIT_IDV_BASE}/token`, {
    method: "POST",
    headers: {
      "Content-Type": "application/x-www-form-urlencoded",
      Authorization: `Basic ${basicAuth(event)}`,
    },
    body: new URLSearchParams({
      grant_type: "authorization_code",
      code,
      code_verifier: verifier,
      redirect_uri: `https://${event.request.hostname}/continue`,
    }).toString(),
  });
  if (!res.ok) return api.access.deny("Identity verification could not be confirmed.");

  const { id_token } = await res.json();
  // This token comes directly from Didit's token endpoint over TLS with client
  // authentication (the trusted back-channel), so decoding is sufficient here.
  // For defense-in-depth, verify the RS256 signature against the JWKS endpoint
  // (plus iss / aud / exp / nonce) before trusting it.
  const payload = JSON.parse(Buffer.from(id_token.split(".")[1], "base64url").toString());
  const verification = payload.verified_claims?.[0]?.verification ?? {};

  if (verification.trust_framework === "IDV-DELEGATED" && verification.assurance_level === "VERIFIED") {
    api.user.setAppMetadata("idv_status", "verified");
    api.user.setAppMetadata("idv_session", verification.verification_process ?? null);
  } else {
    api.access.deny("Identity verification failed.");
  }
};