JWT Authentication with Node.js

JWT (JSON Web Token) authentication is a popular method for securing APIs and web applications. In this article, we will explore how to implement JWT authentication with Node.js.

What is JWT?

JWT is a standard for securely transmitting information between parties as a JSON object. It can be used to authenticate and authorize users. JWTs are signed with a secret key or public/private key pair, which allows them to be verified and trusted.

Implementing JWT Authentication with Node.js

To implement JWT authentication in a Node.js application, we will need to use a few libraries: jsonwebtoken for creating and verifying tokens, and express for building the API.

First, we need to install the required libraries:

npm install jsonwebtoken express
  

Next, we can create a simple Node.js API and implement JWT authentication. Here’s an example:

// server.js
  const express = require('express');
  const jwt = require('jsonwebtoken');
  const app = express();

  app.use(express.json());

  const secretKey = 'your_secret_key';

  app.post('/login', (req, res) => {
    // Assume we have a user with username and password
    const { username, password } = req.body;

    // Check if the username and password are valid
    if (username === 'john' && password === 'doe') {
      // If the credentials are valid, create and send a JWT token
      const token = jwt.sign({ username }, secretKey, { expiresIn: '1h' });
      res.json({ token });
    } else {
      res.status(401).json({ message: 'Invalid credentials' });
    }
  });

  app.get('/protected', (req, res) => {
    // Verify the JWT token
    const token = req.headers.authorization.split(' ')[1];
    try {
      jwt.verify(token, secretKey);
      res.json({ message: 'Protected resource accessed' });
    } catch (error) {
      res.status(401).json({ message: 'Unauthorized' });
    }
  });

  app.listen(3000, () => {
    console.log('Server started on port 3000');
  });
  

In this example, we have created an API with two endpoints: ‘/login’ for user authentication and ‘/protected’ for accessing a protected resource. When a user logs in, a JWT token is created and sent back to the client. The client can then include this token in the Authorization header to access the protected resource.

Conclusion

JWT authentication is a powerful and secure method for protecting APIs and web applications. With Node.js and the jsonwebtoken library, it is easy to implement JWT authentication in your projects. By following the example in this article, you can create a secure and reliable authentication system for your Node.js applications.