How do you implement JWT-based authentication in Spring Boot?

Table of Contents

• Introduction
• Steps to Implement JWT-Based Authentication in Spring Boot
  • Step 1: Add Required Dependencies
    • Example pom.xml:
  • Step 2: Create a JWT Utility Class
    • Example JwtUtil.java:
  • Step 3: Create an Authentication Filter
    • Example JwtAuthenticationFilter.java:
  • Step 4: Configure Spring Security to Use the JWT Filter
    • Example SecurityConfig.java:
  • Step 5: Create the Authentication Endpoint
    • Example AuthController.java:
  • Step 6: Test JWT Authentication
• Conclusion

Introduction

JSON Web Tokens (JWT) are a popular choice for securing RESTful APIs due to their compact, URL-safe nature. JWT allows for stateless authentication, meaning the server does not need to maintain session data. In Spring Boot applications, implementing JWT-based authentication enables secure communication between the client and server, providing both authentication and authorization.

This guide will show you how to implement JWT-based authentication in a Spring Boot application using Spring Security. We will cover the following topics:

1. Creating a JWT utility class.
2. Configuring Spring Security for JWT authentication.
3. Implementing a custom filter for JWT token validation.
4. Handling JWT token creation and validation during login.

Steps to Implement JWT-Based Authentication in Spring Boot

Step 1: Add Required Dependencies

To start, you'll need to add dependencies for Spring Security and JWT. You can add these dependencies to your pom.xml file.

Example pom.xml:

• spring-boot-starter-security: Includes the necessary classes for Spring Security.
• jjwt: A library for creating and parsing JWT tokens.

Step 2: Create a JWT Utility Class

The JWT utility class will handle the creation, parsing, and validation of JWT tokens. It will provide methods to generate tokens, parse them, and verify their authenticity.

Example JwtUtil.java:

Step 3: Create an Authentication Filter

To authenticate requests with JWT, you'll need to create a custom filter that intercepts incoming HTTP requests and validates the JWT token in the Authorization header.

Example JwtAuthenticationFilter.java:

Step 4: Configure Spring Security to Use the JWT Filter

Now you need to configure Spring Security to use the JwtAuthenticationFilter for validating JWT tokens on each request. You can achieve this by overriding the configure(HttpSecurity http) method in your security configuration.

Example SecurityConfig.java:

Step 5: Create the Authentication Endpoint

You'll need an endpoint where users can authenticate and get a JWT token. This is usually done by providing the username and password, validating the credentials, and then returning a JWT token.

Example AuthController.java:

Step 6: Test JWT Authentication

1. Authenticate: Make a POST request to /authenticate with username and password parameters to get the JWT token.
2. Access Protected Endpoints: Include the returned JWT token in the Authorization header as Bearer <token> for requests to protected endpoints.

Example Request:

Example Protected Request:

Conclusion

Implementing JWT-based authentication in Spring Boot provides a secure and stateless way to authenticate users and protect your API endpoints. By following the steps above, you can create a custom JWT utility class, configure Spring Security with a custom filter for JWT validation, and set up authentication endpoints that return JWT tokens.

JWT tokens simplify authentication by allowing users to authenticate once and continue to interact with the server without needing to re-authenticate on every request, improving performance and scalability.