In the previous article, we built a secure JWT-based authentication system using Spring Security 7. While JWT works well for custom authentication, many modern applications allow users to sign in using existing accounts such as Google, GitHub, Microsoft, or Facebook. This approach, known as Social Authentication, improves the user experience by eliminating the need to create and manage another username and password.
Spring Security provides built-in support for OAuth2 and OpenID Connect (OIDC), making it straightforward to integrate third-party identity providers into Spring Boot applications.
What is OAuth2?
OAuth2 (OAuth 2.0) is an authorization framework that allows an application to access a user's resources on another platform without handling the user's password. Instead of sharing credentials, the user grants permission through an authorization process, and the application receives an access token to access approved resources.
For example, when you click "Continue with Google", your application redirects you to Google's login page. After successful authentication and user consent, Google returns an access token that your application can use to retrieve basic profile information.
What is OpenID Connect?
OpenID Connect (OIDC) is an identity layer built on top of OAuth2. While OAuth2 focuses on authorization, OpenID Connect adds authentication by providing an ID Token containing verified user information such as the user's name, email address, and unique identifier.
Most modern identity providers, including Google, Microsoft, Okta, and Auth0, support OpenID Connect.
OAuth2 Authentication Flow
The authentication process follows these steps:
The user clicks Login with Google.
The application redirects the user to Google's authorization server.
The user signs in and grants permission.
Google returns an authorization code.
Spring Security exchanges the code for an access token and ID token.
User information is retrieved, and the user is authenticated.
The application creates a secure session or issues a JWT for subsequent API requests.
Why Use OAuth2?
OAuth2 and OpenID Connect offer several advantages:
Faster user registration and login
No need to store user passwords
Trusted authentication from providers like Google and GitHub
Better security through industry-standard protocols
Seamless integration with cloud-native and enterprise applications
Summary
In this article, we introduced OAuth2, Social Authentication, and OpenID Connect, and learned how they work together to provide secure authentication. In the next part, we will configure Google and GitHub OAuth2 Login in a Spring Boot 4 application using Spring Security 7 and implement a production-ready authentication flow.
