Federated Identity

Federated Identity Overview

Federated Identity 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 federated identity focused and predictable. Start from the minimal example here, then layer in only the complexity your feature actually needs.

import express from 'express';
import jwt from 'jsonwebtoken';

const app = express();
app.use(express.json());

function authenticate(req, res, next) {
  const token = req.headers.authorization?.replace('Bearer ', '');
  try {
    req.user = jwt.verify(token, process.env.JWT_SECRET);
    next();
  } catch {
    res.status(401).json({ error: 'Unauthorized' });
  }
}

Authentication middleware verifies the caller's identity before protected handlers run.

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

Authentication Cheatsheet

Quick authentication reference related to federated identity.

How Federated Identity Works

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

Authentication middleware verifies the caller's identity before protected handlers run.

• 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 Federated Identity

Security is the whole point of federated identity. 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 federated identity.
• Leaving federated identity untested, so regressions slip into production.
• Over-engineering federated identity before you actually need the extra flexibility.
• Ignoring documentation, which makes federated identity hard for the next developer to change.

Key Takeaways

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