Java Authentication & Authorization (JWT, OAuth2) Tutorial

Understanding Authentication & Authorization

Authentication verifies user identity, while Authorization determines access permissions.

What is JWT?

• JWT (JSON Web Token) is a compact token format used for authentication.
• Tokens contain encoded header, payload, and signature.
• Useful for stateless authentication in REST APIs.

Implementing JWT Authentication

1. Create a login endpoint to authenticate users.
2. Generate a JWT upon successful login.
3. Protect API routes using JWT validation.

What is OAuth2?

• OAuth2 is an authorization framework for delegating access without sharing credentials.
• Used by major platforms like Google, Facebook, and GitHub.

Implementing OAuth2 Authorization

1. Register your application with an OAuth2 provider.
2. Configure OAuth2 client in your Java application.
3. Handle authentication and authorization flows using OAuth2 tokens.

Best Practices for Security

• Use HTTPS to secure token transmission.
• Set short expiration times for JWTs.
• Implement refresh tokens for OAuth2 sessions.
• Validate and sanitize all input data.