**Course Title:** Mastering Node.js: Building Scalable Web Applications **Section Title:** Authentication and Authorization **Topic:** Implement authentication and authorization in a Node.js application using JWT and role-based access control.(Lab topic) **Overview** In this lab topic, we will implement authentication and authorization in a Node.js application using JSON Web Tokens (JWT) and role-based access control. We will cover the following topics: 1. Introduction to JWT 2. Implementing JWT authentication in Node.js 3. Role-based access control in Node.js 4. Implementing role-based access control using JWT 5. Best practices for securing APIs **Introduction to JWT** JSON Web Tokens (JWT) is a compact, URL-safe means of representing claims to be transferred between two parties. The token is digitally signed and contains a payload that can be verified and trusted. **Implementing JWT authentication in Node.js** To implement JWT authentication in Node.js, we will use the `jsonwebtoken` package. Here's an example of how to use it: ```javascript const jwt = require('jsonwebtoken'); // Generate a secret key const secretKey = 'your-secret-key'; // Create a token const token = jwt.sign({ userId: 1, role: 'admin' }, secretKey, { expiresIn: '1h', }); console.log(token); ``` **Role-based access control in Node.js** Role-based access control (RBAC) is a method of controlling access to resources based on a user's role. In Node.js, we can implement RBAC using a middleware function that checks the user's role before allowing access to a resource. **Implementing role-based access control using JWT** To implement role-based access control using JWT, we will use the `jsonwebtoken` package to verify the token and check the user's role. Here's an example of how to use it: ```javascript const jwt = require('jsonwebtoken'); // Generate a secret key const secretKey = 'your-secret-key'; // Verify the token const token = req.header('Authorization'); const decoded = jwt.verify(token, secretKey); // Check the user's role if (decoded.role === 'admin') { // Allow access to the resource res.send('Hello, admin!'); } else { // Deny access to the resource res.status(403).send('Forbidden'); } ``` **Best practices for securing APIs** To secure APIs, we should follow these best practices: 1. Use HTTPS to encrypt data in transit. 2. Use a secure secret key to sign and verify tokens. 3. Use a secure algorithm to hash passwords. 4. Implement rate limiting to prevent brute-force attacks. 5. Implement IP blocking to prevent IP spoofing attacks. **Conclusion** In this lab topic, we implemented authentication and authorization in a Node.js application using JWT and role-based access control. We covered the basics of JWT, implemented JWT authentication, and implemented role-based access control using JWT. We also discussed best practices for securing APIs. **Additional Resources** * JSON Web Tokens (JWT) specification: <https://tools.ietf.org/html/rfc7519> * `jsonwebtoken` package documentation: <https://www.npmjs.com/package/jsonwebtoken> * OWASP Secure Coding Practices: <https://owasp.org/www-project-secure-coding-practices/> **Leave a comment or ask for help if you have any questions or need further clarification on any of the topics covered in this lab topic.**

const jwt = require('jsonwebtoken');

// Generate a secret key
const secretKey = 'your-secret-key';

// Create a token
const token = jwt.sign({ userId: 1, role: 'admin' }, secretKey, {
  expiresIn: '1h',
});

console.log(token);

const jwt = require('jsonwebtoken');

// Generate a secret key
const secretKey = 'your-secret-key';

// Verify the token
const token = req.header('Authorization');
const decoded = jwt.verify(token, secretKey);

// Check the user's role
if (decoded.role === 'admin') {
  // Allow access to the resource
  res.send('Hello, admin!');
} else {
  // Deny access to the resource
  res.status(403).send('Forbidden');
}