Free Trial Abuse

<script type="module">
  const mod = await import(
    'https://cdn.shieldlabs.ai/snippet.js?publicKey=YOUR_PUBLIC_KEY'
  );
  // A fresh identification for the trial start, started when the page opens
  // so it is sent while the user reads it. onInitialized fires when the check
  // starts, before the snippet sends it, so it only stores the request ID and
  // the form submits normally. With no request ID, your backend holds the trial.
  // The new account's hashed id, rendered by your server after signup.
  // Never a raw email or user id.
  mod.forceCheckAuthenticatedUser('8a9f-hashed-account-id', {
    onInitialized: (result) => {
      if (result.status === 'initialized') {
        document.getElementById('shieldlabs-request-id').value = result.requestID;
      }
    },
  });
</script>

<form id="trial-form" method="POST" action="/api/start-trial">
  <input type="hidden" id="shieldlabs-request-id" name="shieldlabsRequestId" />
  <button type="submit">Start free trial</button>
</form>

import { app, waitForScore, band, accountView, accountsBehindDevice, NIL_DEVICE } from '../shieldlabs-helpers.js';

app.post('/api/start-trial', async (req, res) => {
  const { shieldlabsRequestId } = req.body;
  const accountId = req.user.id;
  const userHid = req.user.hashedId; // the new account's hashed id, as passed to the snippet

  // 1. Your normal eligibility checks first (not already trialed by this
  //    account, within campaign window, terms accepted).
  if (!(await trialIsAvailable(accountId))) {
    return res.status(409).json({ error: 'trial_not_available' });
  }

  // 2. The guard: read this trial start's identification. No identification
  //    is unverified, never clean.
  const risk = await waitForScore(shieldlabsRequestId, 2000);
  if (!risk) {
    return res.json({ requireVerification: true, reason: 'no_identification' });
  }
  if (risk.user_hid !== userHid) {
    return res.json({ requireVerification: true, reason: 'identification_mismatch' });
  }
  if (risk.risk_score > 100) {
    // The 999 rate-limit marker.
    return res.json({ requireVerification: true, reason: 'rate_limit_marker' });
  }

  // 3. The account: your Multi-accounting mark ('medium' or 'high', your own
  //    store), then its earlier identifications without this one.
  const marked = await markedAccounts.get(userHid);
  if (marked === 'high') {
    return res.status(403).json({ error: 'trial_denied', reason: 'held_for_review' });
  }
  // A failed History read is unverified: hold the trial.
  const account = await accountView(userHid, { excludeRequestId: risk.request_id }).catch(() => null);
  if (!account) return res.json({ requireVerification: true, reason: 'history_unavailable' });
  if (marked || account.worstBand === 'Dangerous') {
    return res.json({ requireVerification: true, reason: 'risky_account' });
  }

  // 4. An all-zero Device ID means no usable device signals reached ShieldLabs:
  //    there is no device to count trials on, so hold the trial.
  if (risk.device_id === NIL_DEVICE) {
    return res.json({ requireVerification: true, reason: 'no_device' });
  }

  // 5. Distinct accounts behind this device ("anonymous" is not an account).
  const accountsOnDevice = await accountsBehindDevice(risk.device_id).catch(() => null);
  if (accountsOnDevice === null) {
    return res.json({ requireVerification: true, reason: 'history_unavailable' });
  }
  if (accountsOnDevice >= YOUR_TRIAL_LIMIT) {
    return res.json({ requireVerification: true, reason: 'trials_on_device' });
  }

  // 6. The trial start itself. Branch on the band, never on a label string.
  if (band(risk.risk_score) === 'Dangerous') {
    return res.json({ requireVerification: true, reason: 'risk_signals' });
  }

  // Trusted or Suspicious, a clean account and a fresh device: grant the trial.
  return grantTrial(req, res);
});

curl "https://account.shieldlabs.ai/api/v1/history/device_id/5eb7fd5c-2a1b-4c3d-9e8f-7a6b5c4d3e2f?limit=100" \
  -H "Authorization: Bearer sec_your_private_api_key"