Trusted Devices

Trusted Devices Overview

Trusted Devices lets you structure authentication work so it stays readable, testable, and easy to scale. Instead of ad-hoc code, you follow a clear pattern that other developers can recognise immediately.

The key is to keep trusted devices focused and predictable. Start from the minimal example here, then layer in only the complexity your feature actually needs.

import session from 'express-session';

app.use(session({
  secret: process.env.SESSION_SECRET,
  resave: false,
  saveUninitialized: false,
  cookie: { httpOnly: true, secure: true, sameSite: 'lax', maxAge: 3600000 },
}));

app.post('/login', (req, res) => {
  req.session.userId = user.id;
  res.json({ ok: true });
});

Session auth stores a server-side session and sends the user a secure, httpOnly cookie.

Trusted Devices Example

// verify the caller on every protected request
function authenticate(req, res, next) {
  const token = req.headers.authorization?.replace('Bearer ', '');
  req.user = verifyToken(token); // throws if invalid
  next();
}

• Start from a minimal Trusted Devices example and grow it only as needed.
• Keep configuration explicit so Trusted Devices behaves the same in every environment.
• Name things clearly so teammates understand your Trusted Devices at a glance.
• Add tests around Trusted Devices early to lock in expected behaviour.

Authentication Cheatsheet

Quick authentication reference related to trusted devices.

How Trusted Devices Works

Trusted Devices is part of proving who a user is and what they are allowed to do. Authentication verifies identity, while authorization decides access — and trusted devices plays a specific role in that flow.

Session auth stores a server-side session and sends the user a secure, httpOnly cookie.

• Never store or log plain-text passwords or secrets.
• Prefer short-lived tokens with refresh over long-lived ones.
• Always send credentials over HTTPS.
• Fail closed: deny access when anything is uncertain.

Security Guidance for Trusted Devices

Security is the whole point of trusted devices. Small mistakes — weak hashing, tokens in localStorage, missing rate limits — are exactly what attackers look for, so follow proven defaults.

Common Mistakes

• Skipping error handling and edge cases when wiring up trusted devices.
• Leaving trusted devices untested, so regressions slip into production.
• Over-engineering trusted devices before you actually need the extra flexibility.
• Ignoring documentation, which makes trusted devices hard for the next developer to change.

Key Takeaways

• Trusted Devices is a core part of working effectively with authentication.
• Start small and keep trusted devices focused on a single responsibility.
• Apply consistent patterns so trusted devices scales across your project.
• Test and document trusted devices to keep it maintainable over time.