Edge Computing with Cloudflare Workers & Deno · Lesson

Authentication & Authorization

Implement user authentication and authorization strategies for securing your edge API endpoints.

Authentication & Authorization is a free Edge Computing with Cloudflare Workers & Deno lesson on CoddyKit — lesson 1 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Edge Computing with Cloudflare Workers & Deno learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Securing Edge APIs

Welcome! In this lesson, we'll dive into Authentication and Authorization for your edge API endpoints.

These are crucial concepts for protecting your applications and ensuring only the right users can access specific resources.

AuthN vs. AuthZ

Let's clarify two key terms:

Authentication (AuthN): Verifies who you are. Think of it like showing your ID to prove your identity.
Authorization (AuthZ): Determines what you can do. This is like your ID granting you access to certain areas, but not others.

They often work together, but are distinct processes.

Common Edge Auth Methods

At the edge, we need lightweight and efficient authentication methods. Common approaches include:

API Keys: Simple secrets used to identify an application or user.
JSON Web Tokens (JWTs): Self-contained, digitally signed tokens for secure information exchange.
OAuth/OIDC: More complex protocols for delegated authorization, often relying on JWTs.

We'll focus on API Keys and JWTs.

Implementing API Key Auth

API Keys are straightforward. A client sends a secret key, usually in a header, and your Worker validates it. Let's see a simple example:

export default {
  async fetch(request, env, ctx) {
    const apiKey = request.headers.get('X-API-Key');

    // In a real app, fetch 'MY_API_KEY' from env.MY_API_KEY
    if (apiKey !== 'super-secret-key-123') {
      return new Response('Unauthorized: Invalid API Key', { status: 401 });
    }

    return new Response('Access Granted!', { status: 200 });
  },
};

API Key Auth Explained

In the example, the Worker checks for the X-API-Key header. If it doesn't match our expected secret, access is denied with a 401 Unauthorized status.

For production, always store your API keys securely, typically in Cloudflare Worker environment variables, not directly in your code.

JSON Web Tokens (JWTs)

JWTs are powerful for edge applications because they are self-contained. Once issued by an identity provider, a JWT can be verified by your Worker without needing to contact a central server every time.

A JWT has three parts: Header, Payload, and Signature, separated by dots.

Verifying JWTs on the Edge

Your Worker will receive a JWT, usually in the Authorization: Bearer header. The critical step is to verify its signature to ensure it hasn't been tampered with.

While full cryptographic verification requires a library, here's where you'd typically extract and prepare for verification:

export default {
  async fetch(request, env, ctx) {
    const authHeader = request.headers.get('Authorization');
    if (!authHeader || !authHeader.startsWith('Bearer ')) {
      return new Response('Unauthorized: No token', { status: 401 });
    }

    const token = authHeader.split(' ')[1];

    // In a real app, you'd use a crypto library and a secret key
    // to verify the token's signature, expiry, and claims.
    // e.g., using 'jose' library with `await jwtVerify(token, secretKey)`
    if (token) {
      // For this example, we'll assume a successful (mock) verification
      return new Response('Access Granted with JWT!', { status: 200 });
    }

    return new Response('Unauthorized: Invalid JWT', { status: 401 });
  },
};

Role-Based Authorization (RBAC)

Once a user is authenticated (e.g., via a verified JWT), you need to decide what actions they are authorized to perform. This is where Role-Based Access Control (RBAC) comes in.

RBAC assigns permissions to roles (e.g., 'admin', 'user', 'guest'), and users are assigned one or more roles. Your Worker then checks the user's role before allowing an action.

Implementing RBAC in Worker

You can embed user roles or permissions directly into the JWT payload as 'claims'. After verifying the JWT, your Worker can read these claims and enforce authorization rules.

export default {
  async fetch(request, env, ctx) {
    // Assume JWT is already verified and we have the user's role
    // In a real app, this 'userRole' would come from the decoded JWT payload.
    const userRole = 'editor'; // Example role from a verified token

    if (request.url.includes('/admin') && userRole !== 'admin') {
      return new Response('Forbidden: Admins only!', { status: 403 });
    }

    if (request.method === 'POST' && userRole === 'guest') {
        return new Response('Forbidden: Guests cannot create!', { status: 403 });
    }

    return new Response(`Welcome, ${userRole}! Request processed.`, { status: 200 });
  },
};

Test Your Understanding

Which of the following statements correctly describe the difference between Authentication and Authorization?

Recap: AuthN & AuthZ

Great job! You've learned the fundamentals of securing your edge APIs.

Authentication confirms identity.
Authorization controls access.
API Keys offer simple authentication.
JWTs provide secure, self-contained authentication and can carry authorization claims.
RBAC (Role-Based Access Control) helps define permissions based on user roles.

These strategies are vital for building robust and secure edge applications.

Frequently asked questions

Is the “Authentication & Authorization” lesson free?

Yes — the full text of “Authentication & Authorization” is free to read here on the web, and the Edge Computing with Cloudflare Workers & Deno course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Edge Computing with Cloudflare Workers & Deno course, upgrade to CoddyKit PRO.

What will I learn in “Authentication & Authorization”?

Implement user authentication and authorization strategies for securing your edge API endpoints. You practise Edge Computing with Cloudflare Workers & Deno with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Edge Computing with Cloudflare Workers & Deno?

No prior experience is required. Edge Computing with Cloudflare Workers & Deno on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Authentication & Authorization” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Edge Computing with Cloudflare Workers & Deno lesson?

Yes. Every Edge Computing with Cloudflare Workers & Deno lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

Authentication & Authorization
Rate Limiting & DDoS Protection
Secure Secrets Management
Input Sanitization & Injection Prevention

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