Pros of Spring Security

• More actively maintained and regularly updated
• Broader scope, covering various security aspects beyond OAuth
• Better integration with the Spring ecosystem

Cons of Spring Security

• Steeper learning curve due to its comprehensive nature
• May be overkill for simple OAuth-only implementations
• Requires more configuration for basic OAuth setups

Code Comparison

Spring Security OAuth:

@Configuration
@EnableAuthorizationServer
public class AuthServerConfig extends AuthorizationServerConfigurerAdapter {
    // OAuth2 server configuration
}

Spring Security:

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.oauth2Login();
    }
}

Key Differences

• Spring Security OAuth is focused solely on OAuth and OpenID Connect
• Spring Security provides a more comprehensive security solution
• Spring Security OAuth is now in maintenance mode, while Spring Security is actively developed
• Spring Security requires more setup for OAuth but offers greater flexibility
• Spring Security OAuth has simpler configuration for basic OAuth scenarios

Recommendation

Choose Spring Security for new projects or when requiring a full security solution. Opt for Spring Security OAuth only if maintaining legacy projects or needing a lightweight OAuth-specific implementation.

Pros of spring-authorization-server

• More modern and actively maintained
• Better alignment with latest OAuth 2.0 and OpenID Connect specifications
• Improved security features and best practices

Cons of spring-authorization-server

• Less mature and potentially fewer community resources
• May require migration efforts for existing spring-security-oauth users
• Steeper learning curve for developers familiar with the older library

Code Comparison

spring-security-oauth:

@Configuration
@EnableAuthorizationServer
public class AuthServerConfig extends AuthorizationServerConfigurerAdapter {
    @Override
    public void configure(ClientDetailsServiceConfigurer clients) throws Exception {
        clients.inMemory().withClient("client-id").secret("secret").scopes("read", "write");
    }
}

spring-authorization-server:

@Configuration
@Import(OAuth2AuthorizationServerConfiguration.class)
public class AuthServerConfig {
    @Bean
    public RegisteredClientRepository registeredClientRepository() {
        RegisteredClient client = RegisteredClient.withId("client-id")
            .clientSecret("secret").scopes("read", "write").build();
        return new InMemoryRegisteredClientRepository(client);
    }
}

The spring-authorization-server example demonstrates a more modular and flexible approach to client configuration, utilizing the RegisteredClientRepository for managing client details.

Pros of Keycloak

• Comprehensive identity and access management solution with a wide range of features
• Active development and regular updates
• Supports multiple protocols and standards out of the box (OAuth 2.0, OpenID Connect, SAML)

Cons of Keycloak

• Steeper learning curve due to its extensive feature set
• Requires more resources to run compared to Spring Security OAuth
• May be overkill for simple authentication scenarios

Code Comparison

Spring Security OAuth:

@Configuration
@EnableAuthorizationServer
public class AuthServerConfig extends AuthorizationServerConfigurerAdapter {
    // Configuration code here
}

Keycloak:

@Configuration
public class KeycloakConfig {
    @Bean
    public KeycloakSpringBootConfigResolver keycloakConfigResolver() {
        return new KeycloakSpringBootConfigResolver();
    }
}

Additional Notes

• Spring Security OAuth is now in maintenance mode, while Keycloak is actively developed
• Keycloak offers a user-friendly admin console for managing users, roles, and clients
• Spring Security OAuth integrates more seamlessly with Spring Boot applications
• Keycloak provides built-in support for social login and user federation
• Both projects have extensive documentation, but Keycloak's is more comprehensive due to its broader feature set

Pros of pac4j

• Multi-protocol support: Handles various authentication mechanisms (OAuth, SAML, OpenID Connect, etc.)
• Framework-agnostic: Can be integrated with different Java web frameworks
• Active development and community support

Cons of pac4j

• Steeper learning curve due to its flexibility and extensive features
• Less Spring-specific optimizations compared to Spring Security OAuth

Code Comparison

pac4j:

Config config = new Config(new GoogleOidcClient(clientId, clientSecret));
SecurityFilter filter = new SecurityFilter(config, "GoogleOidcClient");

Spring Security OAuth:

@EnableOAuth2Client
public class OAuth2ClientConfig {
    @Bean
    public OAuth2RestTemplate oauth2RestTemplate(OAuth2ClientContext context) {
        return new OAuth2RestTemplate(google(), context);
    }
}

Key Differences

• pac4j offers a more generic approach, suitable for various Java frameworks
• Spring Security OAuth is tightly integrated with the Spring ecosystem
• pac4j provides more authentication protocols out-of-the-box
• Spring Security OAuth has better Spring-specific performance optimizations

Use Cases

• Choose pac4j for multi-framework projects or when requiring diverse authentication methods
• Opt for Spring Security OAuth in Spring-based applications for seamless integration

Community and Support

• pac4j has an active community and regular updates
• Spring Security OAuth is in maintenance mode, with new features directed to Spring Security 5.x

Pros of CAS

• More comprehensive authentication and authorization solution
• Supports a wider range of protocols (SAML, OAuth, CAS, etc.)
• Active development and community support

Cons of CAS

• Steeper learning curve due to its complexity
• Requires more configuration and setup compared to Spring Security OAuth

Code Comparison

CAS configuration example:

<bean id="centralAuthenticationService" class="org.apereo.cas.CentralAuthenticationServiceImpl">
    <property name="ticketRegistry" ref="ticketRegistry" />
    <property name="serviceTicketExpirationPolicy" ref="serviceTicketExpirationPolicy" />
    <property name="authenticationManager" ref="authenticationManager" />
</bean>

Spring Security OAuth configuration example:

@Configuration
@EnableAuthorizationServer
public class AuthServerConfig extends AuthorizationServerConfigurerAdapter {
    @Override
    public void configure(ClientDetailsServiceConfigurer clients) throws Exception {
        clients.inMemory()
            .withClient("client-id")
            .secret("secret")
            .authorizedGrantTypes("authorization_code")
            .scopes("read", "write");
    }
}

Both projects offer robust authentication solutions, but CAS provides a more comprehensive platform for enterprise-level authentication and single sign-on. Spring Security OAuth, while simpler to set up, focuses primarily on OAuth2 implementation. CAS requires more initial configuration but offers greater flexibility and protocol support. The choice between the two depends on specific project requirements and the desired level of complexity.

Pros of jjwt

• Lightweight and focused solely on JSON Web Tokens (JWT)
• Easy to use and integrate into existing projects
• Actively maintained and regularly updated

Cons of jjwt

• Limited to JWT functionality, lacking broader OAuth 2.0 support
• May require additional libraries for complete authentication solutions
• Less comprehensive documentation compared to Spring Security OAuth

Code Comparison

spring-security-oauth:

OAuth2RestTemplate template = new OAuth2RestTemplate(resource, new DefaultOAuth2ClientContext(accessTokenRequest));
OAuth2AccessToken token = template.getAccessToken();

jjwt:

String jws = Jwts.builder()
    .setSubject("user123")
    .signWith(SignatureAlgorithm.HS256, "secret")
    .compact();

Summary

jjwt is a specialized library for JWT handling, offering simplicity and ease of use. It's ideal for projects that specifically need JWT functionality. Spring Security OAuth, while no longer actively maintained, provides a more comprehensive OAuth 2.0 solution with broader authentication and authorization capabilities. The choice between the two depends on the project's specific requirements and the desired level of integration with the Spring ecosystem.