Spring Security

OAuth 2.1 is an updated version of the OAuth 2.0 authorization framework, providing enhanced security features and clarifications. It addresses some of the limitations and ambiguities present in OAuth 2.0, making it more robust for modern applications. In this guide, we’ll walk through implementing OAuth 2.1 with Spring Security 6, covering client setup, authorization server configuration, and resource server integration. What is OAuth 2.1? OAuth 2.1 builds upon OAuth 2.0 by introducing several improvements, such as Proof Key for Code Exchange (PKCE) for public clients, safer handling of authorization codes, and more secure token exchange processes. These enhancements aim to protect against common vulnerabilities like authorization code interception and client impersonation. ...

Integrating Keycloak with Spring Boot for OAuth2 resource server protection is one of the most searched tasks in the IAM developer community — yet most tutorials stop at “hello world” level. This guide covers production-grade integration: JWT validation, Keycloak realm role extraction, multi-tenant setups, and integration testing strategies. Clone the companion repo: All working code in this guide is available at github.com/IAMDevBox/keycloak-spring-boot-oauth2 — includes Docker Compose for Keycloak, complete Spring Boot 3.x application, and integration tests with Testcontainers. ...

I’ve configured SAML SSO for 30+ Spring Boot applications. The setup looks simple in docs, but production always throws curveballs - certificate mismatches, signature validation failures, attribute mapping issues. Here’s what actually works. Visual Overview: sequenceDiagram participant User participant SP as Service Provider participant IdP as Identity Provider User->>SP: 1. Access Protected Resource SP->>User: 2. Redirect to IdP (SAML Request) User->>IdP: 3. SAML AuthnRequest IdP->>User: 4. Login Page User->>IdP: 5. Authenticate IdP->>User: 6. SAML Response (Assertion) User->>SP: 7. POST SAML Response SP->>SP: 8. Validate Assertion SP->>User: 9. Grant Access Clone the companion repo: Get the full working source code with Docker Compose (Keycloak as IdP), multi-IdP config, custom attribute mapping, and integration tests: github.com/IAMDevBox/spring-security-saml-example ...