Delegated Authorization

Delegated Authorization Overview

Delegated Authorization is a building block you will reach for often in authentication. It keeps related logic together and makes your intent obvious to reviewers and future maintainers.

When you learn delegated authorization properly, you avoid the guesswork that leads to bugs and rework. The example below shows the shape you will use in most real authentication projects.

function requireRole(role) {
  return (req, res, next) => {
    if (req.user?.role !== role) {
      return res.status(403).json({ error: 'Forbidden' });
    }
    next();
  };
}

app.delete('/users/:id', requireRole('admin'), deleteUser);

Authorization middleware checks the authenticated user's role before allowing an action.

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

Authentication Cheatsheet

Quick authentication reference related to delegated authorization.

How Delegated Authorization Works

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

Authorization middleware checks the authenticated user's role before allowing an action.

• 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 Delegated Authorization

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

Common Mistakes

• Copying delegated authorization snippets without understanding what each line does.
• Skipping error handling and edge cases when wiring up delegated authorization.
• Leaving delegated authorization untested, so regressions slip into production.
• Over-engineering delegated authorization before you actually need the extra flexibility.

Key Takeaways

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