Difference between Spring Security and OAuth2

1. Introduction

Spring Security is a powerful and highly customizable authentication and access-control framework within the Spring ecosystem. It is the standard way to secure Spring-based applications. OAuth2 is an authorization framework that enables a third-party application to obtain limited access to an HTTP service, which is used across the internet.

2. Key Points

1. Spring Security is a security framework that provides authentication, authorization, and protection against common attacks.

2. OAuth2 is an authorization protocol that enables applications to secure designated access without sharing login credentials.

3. Spring Security can implement various authentication protocols, including OAuth2.

4. OAuth2 can be used independently of Spring Security and can be implemented in any language or framework.

3. Differences

Spring Security	OAuth2
Security framework that provides authentication and authorization.	Authorization framework designed for token-based authentication.
Can be configured to use OAuth2 as an authentication method.	A standalone protocol that can be integrated into various applications.
Specific to the Spring ecosystem.	Universal protocol not limited to Spring or Java.

4. Example

// Spring Security example
@Configuration
@EnableWebSecurity
public class SpringSecurity {

    @Autowired
    private UserDetailsService userDetailsService;

    @Bean
    public static PasswordEncoder passwordEncoder(){
        return new BCryptPasswordEncoder();
    }

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        http.csrf().disable()
                .authorizeHttpRequests((authorize) ->
                        authorize.requestMatchers("/register/**").permitAll()
                                .requestMatchers("/index").permitAll()
                                .requestMatchers("/users").hasRole("ADMIN")
                ).formLogin(
                        form -> form
                                .loginPage("/login")
                                .loginProcessingUrl("/login")
                                .defaultSuccessUrl("/users")
                                .permitAll()
                ).logout(
                        logout -> logout
                                .logoutRequestMatcher(new AntPathRequestMatcher("/logout"))
                                .permitAll()
                );
        return http.build();
    }
    
    @Autowired
    public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
        auth
                .userDetailsService(userDetailsService)
                .passwordEncoder(passwordEncoder());
    }
}

// OAuth2 example
// This is an oversimplified example for illustration purposes only.
@Configuration
@EnableOAuth2Client
public class OAuth2ClientConfig {

    @Bean
    public OAuth2RestTemplate oauth2RestTemplate(OAuth2ClientContext oauth2ClientContext,
                                                  OAuth2ProtectedResourceDetails details) {
        return new OAuth2RestTemplate(details, oauth2ClientContext);
    }
}

Output:

// No direct output; these configurations determine how security is handled in the application.

Explanation:

1. SecurityConfig with Spring Security configures your app to require authentication for any request and to use form-based or HTTP Basic authentication.

2. OAuth2ClientConfig with OAuth2 sets up a client with OAuth2RestTemplate to consume an OAuth2-protected resource.

5. When to use?

- Use Spring Security in a Spring application when you need a full-fledged security solution for authentication and authorization.

- Use OAuth2 when you need to implement authorization in your application, particularly when you are dealing with third-party applications that need to perform actions on behalf of a user without having their credentials.