A minimal Spring Security Maven set of dependencies typically looks like the following:

pom.xml. 

<dependencies>
<!-- ... other dependency elements ... -->
<dependency>
	<groupId>org.springframework.security</groupId>
	<artifactId>spring-security-web</artifactId>
	<version>5.0.3.RELEASE</version>
</dependency>
<dependency>
	<groupId>org.springframework.security</groupId>
	<artifactId>spring-security-config</artifactId>
	<version>5.0.3.RELEASE</version>
</dependency>
</dependencies>

If you are using additional features like LDAP, OpenID, etc. you will need to also include the appropriate Section 2.4.3, “Project Modules”.

<repositories>
<!-- ... possibly other repository elements ... -->
<repository>
	<id>spring-snapshot</id>
	<name>Spring Snapshot Repository</name>
	<url>http://repo.spring.io/snapshot</url>
</repository>
</repositories>

<repositories>
<!-- ... possibly other repository elements ... -->
<repository>
	<id>spring-milestone</id>
	<name>Spring Milestone Repository</name>
	<url>http://repo.spring.io/milestone</url>
</repository>
</repositories>

Spring Framework Bom

Spring Security builds against Spring Framework 5.0.4.RELEASE, but should work with 4.0.x. The problem that many users will have is that Spring Security’s transitive dependencies resolve Spring Framework 5.0.4.RELEASE which can cause strange classpath problems.

One (tedious) way to circumvent this issue would be to include all the Spring Framework modules in a <dependencyManagement> section of your pom. An alternative approach is to include the spring-framework-bom within your <dependencyManagement> section of your pom.xml as shown below:

pom.xml. 

<dependencyManagement>
	<dependencies>
	<dependency>
		<groupId>org.springframework</groupId>
		<artifactId>spring-framework-bom</artifactId>
		<version>5.0.4.RELEASE</version>
		<type>pom</type>
		<scope>import</scope>
	</dependency>
	</dependencies>
</dependencyManagement>

This will ensure that all the transitive dependencies of Spring Security use the Spring 5.0.4.RELEASE modules.

	Note
	This approach uses Maven’s "bill of materials" (BOM) concept and is only available in Maven 2.0.9+. For additional details about how dependencies are resolved refer to Maven’s Introduction to the Dependency Mechanism documentation.

A minimal Spring Security Gradle set of dependencies typically looks like the following:

build.gradle. 

dependencies {
	compile 'org.springframework.security:spring-security-web:5.0.3.RELEASE'
	compile 'org.springframework.security:spring-security-config:5.0.3.RELEASE'
}

If you are using additional features like LDAP, OpenID, etc. you will need to also include the appropriate Section 2.4.3, “Project Modules”.

repositories {
	mavenCentral()
}

repositories {
	maven { url 'https://repo.spring.io/snapshot' }
}

repositories {
	maven { url 'https://repo.spring.io/milestone' }
}

Using Spring 4.0.x and Gradle

By default Gradle will use the newest version when resolving transitive versions. This means that often times no additional work is necessary when running Spring Security 5.0.3.RELEASE with Spring Framework 5.0.4.RELEASE. However, at times there can be issues that come up so it is best to mitigate this using Gradle’s ResolutionStrategy as shown below:

build.gradle. 

configurations.all {
	resolutionStrategy.eachDependency { DependencyResolveDetails details ->
		if (details.requested.group == 'org.springframework') {
			details.useVersion '5.0.4.RELEASE'
		}
	}
}

This will ensure that all the transitive dependencies of Spring Security use the Spring 5.0.4.RELEASE modules.

	Note
	This example uses Gradle 1.9, but may need modifications to work in future versions of Gradle since this is an incubating feature within Gradle.

In Spring Security 3.0, the codebase has been sub-divided into separate jars which more clearly separate different functionality areas and third-party dependencies. If you are using Maven to build your project, then these are the modules you will add to your pom.xml. Even if you’re not using Maven, we’d recommend that you consult the pom.xml files to get an idea of third-party dependencies and versions. Alternatively, a good idea is to examine the libraries that are included in the sample applications.

Since Spring Security is an Open Source project, we’d strongly encourage you to check out the source code using git. This will give you full access to all the sample applications and you can build the most up to date version of the project easily. Having the source for a project is also a huge help in debugging. Exception stack traces are no longer obscure black-box issues but you can get straight to the line that’s causing the problem and work out what’s happening. The source is the ultimate documentation for a project and often the simplest place to find out how something actually works.

To obtain the source for the project, use the following git command:

git clone https://github.com/spring-projects/spring-security.git

This will give you access to the entire project history (including all releases and branches) on your local machine.

The next step is to register the springSecurityFilterChain with the war. This can be done in Java Configuration with Spring’s WebApplicationInitializer support in a Servlet 3.0+ environment. Not suprisingly, Spring Security provides a base class AbstractSecurityWebApplicationInitializer that will ensure the springSecurityFilterChain gets registered for you. The way in which we use AbstractSecurityWebApplicationInitializer differs depending on if we are already using Spring or if Spring Security is the only Spring component in our application.

If you are not using Spring or Spring MVC, you will need to pass in the WebSecurityConfig into the superclass to ensure the configuration is picked up. You can find an example below:

import org.springframework.security.web.context.*;

public class SecurityWebApplicationInitializer
	extends AbstractSecurityWebApplicationInitializer {

	public SecurityWebApplicationInitializer() {
		super(WebSecurityConfig.class);
	}
}

The SecurityWebApplicationInitializer will do the following things:

If we were using Spring elsewhere in our application we probably already had a WebApplicationInitializer that is loading our Spring Configuration. If we use the previous configuration we would get an error. Instead, we should register Spring Security with the existing ApplicationContext. For example, if we were using Spring MVC our SecurityWebApplicationInitializer would look something like the following:

import org.springframework.security.web.context.*;

public class SecurityWebApplicationInitializer
	extends AbstractSecurityWebApplicationInitializer {

}

This would simply only register the springSecurityFilterChain Filter for every URL in your application. After that we would ensure that WebSecurityConfig was loaded in our existing ApplicationInitializer. For example, if we were using Spring MVC it would be added in the getRootConfigClasses()

public class MvcWebApplicationInitializer extends
		AbstractAnnotationConfigDispatcherServletInitializer {

	@Override
	protected Class<?>[] getRootConfigClasses() {
		return new Class[] { WebSecurityConfig.class };
	}

	// ... other overrides ...
}

Generally, LogoutHandler implementations indicate classes that are able to participate in logout handling. They are expected to be invoked to perform necessary clean-up. As such they should not throw exceptions. Various implementations are provided:

Please see Section 18.4, “Remember-Me Interfaces and Implementations” for details.

Instead of providing LogoutHandler implementations directly, the fluent API also provides shortcuts that provide the respective LogoutHandler implementations under the covers. E.g. deleteCookies() allows specifying the names of one or more cookies to be removed on logout success. This is a shortcut compared to adding a CookieClearingLogoutHandler.

The LogoutSuccessHandler is called after a successful logout by the LogoutFilter, to handle e.g. redirection or forwarding to the appropriate destination. Note that the interface is almost the same as the LogoutHandler but may raise an exception.

The following implementations are provided:

As mentioned above, you don’t need to specify the SimpleUrlLogoutSuccessHandler directly. Instead, the fluent API provides a shortcut by setting the logoutSuccessUrl(). This will setup the SimpleUrlLogoutSuccessHandler under the covers. The provided URL will be redirected to after a logout has occurred. The default is /login?logout.

The HttpStatusReturningLogoutSuccessHandler can be interesting in REST API type scenarios. Instead of redirecting to a URL upon the successful logout, this LogoutSuccessHandler allows you to provide a plain HTTP status code to be returned. If not configured a status code 200 will be returned by default.

You can find a minimal WebFlux Security configuration below:

@EnableWebFluxSecurity
public class HelloWebfluxSecurityConfig {

	@Bean
	public MapReactiveUserDetailsService userDetailsService() {
		UserDetails user = User.withDefaultPasswordEncoder()
			.username("user")
			.password("user")
			.roles("USER")
			.build();
		return new MapReactiveUserDetailsService(user);
	}
}

This configuration provides form and http basic authentication, sets up authorization to require an authenticated user for accessing any page, sets up a default log in page and a default log out page, sets up security related HTTP headers, CSRF protection, and more.

You can find an explicit version of the minimal WebFlux Security configuration below:

@EnableWebFluxSecurity
public class HelloWebfluxSecurityConfig {

	@Bean
	public MapReactiveUserDetailsService userDetailsService() {
		UserDetails user = User.withDefaultPasswordEncoder()
			.username("user")
			.password("user")
			.roles("USER")
			.build();
		return new MapReactiveUserDetailsService(user);
	}

	@Bean
	public SecurityWebFilterChain springSecurityFilterChain(ServerHttpSecurity http) {
		http
			.authorizeExchange()
				.anyExchange().authenticated()
				.and()
			.httpBasic().and()
			.formLogin();
		return http.build();
	}
}

This configuration explicitly sets up all the same things as our minimal configuration. From here you can easily make the changes to the defaults.

Spring Boot 2.0 brings full auto-configuration capabilities for OAuth 2.0 Login.

This section shows how to configure the OAuth 2.0 Login sample using Google as the Authentication Provider and covers the following topics:

Initial setup

To use Google’s OAuth 2.0 authentication system for login, you must set up a project in the Google API Console to obtain OAuth 2.0 credentials.

	Note
	Google’s OAuth 2.0 implementation for authentication conforms to the OpenID Connect 1.0 specification and is OpenID Certified.

Follow the instructions on the OpenID Connect page, starting in the section, "Setting up OAuth 2.0".

After completing the "Obtain OAuth 2.0 credentials" instructions, you should have a new OAuth Client with credentials consisting of a Client ID and a Client Secret.

Setting the redirect URI

The redirect URI is the path in the application that the end-user’s user-agent is redirected back to after they have authenticated with Google and have granted access to the OAuth Client (created in the previous step) on the Consent page.

In the "Set a redirect URI" sub-section, ensure that the Authorized redirect URIs field is set to http://localhost:8080/login/oauth2/code/google.

	Tip
	The default redirect URI template is {baseUrl}/login/oauth2/code/{registrationId}. The registrationId is a unique identifier for the ClientRegistration.

ClientRegistration is a representation of a client registered with an OAuth 2.0 or OpenID Connect 1.0 Provider.

A client registration holds information, such as client id, client secret, authorization grant type, redirect URI, scope(s), authorization URI, token URI, and other details.

ClientRegistration and its properties are defined as follows:

public final class ClientRegistration {
	private String registrationId;	
	private String clientId;	
	private String clientSecret;	
	private ClientAuthenticationMethod clientAuthenticationMethod;	
	private AuthorizationGrantType authorizationGrantType;	
	private String redirectUriTemplate;	
	private Set<String> scopes;	
	private ProviderDetails providerDetails;
	private String clientName;	

	public class ProviderDetails {
		private String authorizationUri;	
		private String tokenUri;	
		private UserInfoEndpoint userInfoEndpoint;
		private String jwkSetUri;	

		public class UserInfoEndpoint {
			private String uri;	
			private String userNameAttributeName;	

		}
	}
}

The following table outlines the mapping of the Spring Boot 2.0 OAuth Client properties to the ClientRegistration properties.

The ClientRegistrationRepository serves as a repository for OAuth 2.0 / OpenID Connect 1.0 ClientRegistration(s).

	Note
	Client registration information is ultimately stored and owned by the associated Authorization Server. This repository provides the ability to retrieve a sub-set of the primary client registration information, which is stored with the Authorization Server.

Spring Boot 2.0 auto-configuration binds each of the properties under spring.security.oauth2.client.registration.[registrationId] to an instance of ClientRegistration and then composes each of the ClientRegistration instance(s) within a ClientRegistrationRepository.

	Note
	The default implementation of ClientRegistrationRepository is InMemoryClientRegistrationRepository.

The auto-configuration also registers the ClientRegistrationRepository as a @Bean in the ApplicationContext so that it is available for dependency-injection, if needed by the application.

The following listing shows an example:

@Controller
public class MainController {

	@Autowired
	private ClientRegistrationRepository clientRegistrationRepository;

	@RequestMapping("/")
	public String index() {
		ClientRegistration googleRegistration =
			this.clientRegistrationRepository.findByRegistrationId("google");

		...

		return "index";
	}
}

CommonOAuth2Provider pre-defines a set of default client properties for a number of well known providers: Google, GitHub, Facebook, and Okta.

For example, the authorization-uri, token-uri, and user-info-uri do not change often for a Provider. Therefore, it makes sense to provide default values in order to reduce the required configuration.

As demonstrated previously, when we configured a Google client, only the client-id and client-secret properties are required.

The following listing shows an example:

spring:
  security:
    oauth2:
      client:
        registration:
          google:
            client-id: google-client-id
            client-secret: google-client-secret

	Tip
	The auto-defaulting of client properties works seamlessly here because the registrationId (google) matches the GOOGLE enum (case-insensitive) in CommonOAuth2Provider.

For cases where you may want to specify a different registrationId, such as google-login, you can still leverage auto-defaulting of client properties by configuring the provider property.

The following listing shows an example:

spring:
  security:
    oauth2:
      client:
        registration:
          google-login:	
            provider: google	
            client-id: google-client-id
            client-secret: google-client-secret

There are some OAuth 2.0 Providers that support multi-tenancy, which results in different protocol endpoints for each tenant (or sub-domain).

For example, an OAuth Client registered with Okta is assigned to a specific sub-domain and have their own protocol endpoints.

For these cases, Spring Boot 2.0 provides the following base property for configuring custom provider properties: spring.security.oauth2.client.provider.[providerId].

The following listing shows an example:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            client-id: okta-client-id
            client-secret: okta-client-secret
        provider:
          okta:	
            authorization-uri: https://your-subdomain.oktapreview.com/oauth2/v1/authorize
            token-uri: https://your-subdomain.oktapreview.com/oauth2/v1/token
            user-info-uri: https://your-subdomain.oktapreview.com/oauth2/v1/userinfo
            user-name-attribute: sub
            jwk-set-uri: https://your-subdomain.oktapreview.com/oauth2/v1/keys

The Spring Boot 2.0 Auto-configuration class for OAuth Client support is OAuth2ClientAutoConfiguration.

It performs the following tasks:

If you need to override the auto-configuration based on your specific requirements, you may do so in the following ways:

@Configuration
public class OAuth2LoginConfig {

	@Bean
	public ClientRegistrationRepository clientRegistrationRepository() {
		return new InMemoryClientRegistrationRepository(this.googleClientRegistration());
	}

	private ClientRegistration googleClientRegistration() {
		return ClientRegistration.withRegistrationId("google")
			.clientId("google-client-id")
			.clientSecret("google-client-secret")
			.clientAuthenticationMethod(ClientAuthenticationMethod.BASIC)
			.authorizationGrantType(AuthorizationGrantType.AUTHORIZATION_CODE)
			.redirectUriTemplate("{baseUrl}/login/oauth2/code/{registrationId}")
			.scope("openid", "profile", "email", "address", "phone")
			.authorizationUri("https://accounts.google.com/o/oauth2/v2/auth")
			.tokenUri("https://www.googleapis.com/oauth2/v4/token")
			.userInfoUri("https://www.googleapis.com/oauth2/v3/userinfo")
			.userNameAttributeName(IdTokenClaimNames.SUB)
			.jwkSetUri("https://www.googleapis.com/oauth2/v3/certs")
			.clientName("Google")
			.build();
	}
}

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

	@Override
	protected void configure(HttpSecurity http) throws Exception {
		http
			.authorizeRequests()
				.anyRequest().authenticated()
				.and()
			.oauth2Login();
	}
}

@Configuration
public class OAuth2LoginConfig {

	@EnableWebSecurity
	public static class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

		@Override
		protected void configure(HttpSecurity http) throws Exception {
			http
				.authorizeRequests()
					.anyRequest().authenticated()
					.and()
				.oauth2Login();
		}
	}

	@Bean
	public ClientRegistrationRepository clientRegistrationRepository() {
		return new InMemoryClientRegistrationRepository(this.googleClientRegistration());
	}

	private ClientRegistration googleClientRegistration() {
		return ClientRegistration.withRegistrationId("google")
			.clientId("google-client-id")
			.clientSecret("google-client-secret")
			.clientAuthenticationMethod(ClientAuthenticationMethod.BASIC)
			.authorizationGrantType(AuthorizationGrantType.AUTHORIZATION_CODE)
			.redirectUriTemplate("{baseUrl}/login/oauth2/code/{registrationId}")
			.scope("openid", "profile", "email", "address", "phone")
			.authorizationUri("https://accounts.google.com/o/oauth2/v2/auth")
			.tokenUri("https://www.googleapis.com/oauth2/v4/token")
			.userInfoUri("https://www.googleapis.com/oauth2/v3/userinfo")
			.userNameAttributeName(IdTokenClaimNames.SUB)
			.jwkSetUri("https://www.googleapis.com/oauth2/v3/certs")
			.clientName("Google")
			.build();
	}
}

If you are not able to use Spring Boot 2.0 and would like to configure one of the pre-defined providers in CommonOAuth2Provider (for example, Google), apply the following configuration:

@Configuration
public class OAuth2LoginConfig {

	@EnableWebSecurity
	public static class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

		@Override
		protected void configure(HttpSecurity http) throws Exception {
			http
				.authorizeRequests()
					.anyRequest().authenticated()
					.and()
				.oauth2Login();
		}
	}

	@Bean
	public ClientRegistrationRepository clientRegistrationRepository() {
		return new InMemoryClientRegistrationRepository(this.googleClientRegistration());
	}

	@Bean
	public OAuth2AuthorizedClientService authorizedClientService() {
		return new InMemoryOAuth2AuthorizedClientService(this.clientRegistrationRepository());
	}

	private ClientRegistration googleClientRegistration() {
		return CommonOAuth2Provider.GOOGLE.getBuilder("google")
			.clientId("google-client-id")
			.clientSecret("google-client-secret")
			.build();
	}
}

OAuth2AuthorizedClient is a representation of an Authorized Client. A client is considered to be authorized when the end-user (Resource Owner) has granted authorization to the client to access its protected resources.

OAuth2AuthorizedClient serves the purpose of associating an OAuth2AccessToken to a ClientRegistration (client) and resource owner, who is the Principal end-user that granted the authorization.

The primary role of the OAuth2AuthorizedClientService is to manage OAuth2AuthorizedClient instances. From a developer perspective, it provides the capability to lookup an OAuth2AccessToken associated with a client so that it may be used to initiate a request to a resource server.

	Note
	Spring Boot 2.0 Auto-configuration registers an OAuth2AuthorizedClientService @Bean in the ApplicationContext.

The developer may also register an OAuth2AuthorizedClientService @Bean in the ApplicationContext (overriding Spring Boot 2.0 Auto-configuration) in order to have the ability to lookup an OAuth2AccessToken associated with a specific ClientRegistration (client).

The following listing shows an example:

@Controller
public class MainController {

	@Autowired
	private OAuth2AuthorizedClientService authorizedClientService;

	@RequestMapping("/userinfo")
	public String userinfo(OAuth2AuthenticationToken authentication) {
		// authentication.getAuthorizedClientRegistrationId() returns the
		// registrationId of the Client that was authorized during the Login flow
		OAuth2AuthorizedClient authorizedClient =
			this.authorizedClientService.loadAuthorizedClient(
				authentication.getAuthorizedClientRegistrationId(),
				authentication.getName());

		OAuth2AccessToken accessToken = authorizedClient.getAccessToken();

		...

		return "userinfo";
	}
}

The following additional resources describe advanced configuration options:

We have already seen an example of configuring in-memory authentication for a single user. Below is an example to configure multiple users:

@Bean
public UserDetailsService userDetailsService() throws Exception {
	// ensure the passwords are encoded properly
	UserBuilder users = User.withDefaultPasswordEncoder();
	InMemoryUserDetailsManager manager = new InMemoryUserDetailsManager();
	manager.createUser(users.username("user").password("password").roles("USER").build());
	manager.createUser(users.username("admin").password("password").roles("USER","ADMIN").build());
	return manager;
}

You can find the updates to support JDBC based authentication. The example below assumes that you have already defined a DataSource within your application. The jdbc-javaconfig sample provides a complete example of using JDBC based authentication.

@Autowired
private DataSource dataSource;

@Autowired
public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
	// ensure the passwords are encoded properly
	UserBuilder users = User.withDefaultPasswordEncoder();
	auth
		.jdbcAuthentication()
			.dataSource(dataSource)
			.withDefaultSchema()
			.withUser(users.username("user").password("password").roles("USER"))
			.withUser(users.username("admin").password("password").roles("USER","ADMIN"));
}

You can find the updates to support LDAP based authentication. The ldap-javaconfig sample provides a complete example of using LDAP based authentication.

@Autowired
private DataSource dataSource;

@Autowired
public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
	auth
		.ldapAuthentication()
			.userDnPatterns("uid={0},ou=people")
			.groupSearchBase("ou=groups");
}

The example above uses the following LDIF and an embedded Apache DS LDAP instance.

users.ldif. 

dn: ou=groups,dc=springframework,dc=org
objectclass: top
objectclass: organizationalUnit
ou: groups

dn: ou=people,dc=springframework,dc=org
objectclass: top
objectclass: organizationalUnit
ou: people

dn: uid=admin,ou=people,dc=springframework,dc=org
objectclass: top
objectclass: person
objectclass: organizationalPerson
objectclass: inetOrgPerson
cn: Rod Johnson
sn: Johnson
uid: admin
userPassword: password

dn: uid=user,ou=people,dc=springframework,dc=org
objectclass: top
objectclass: person
objectclass: organizationalPerson
objectclass: inetOrgPerson
cn: Dianne Emu
sn: Emu
uid: user
userPassword: password

dn: cn=user,ou=groups,dc=springframework,dc=org
objectclass: top
objectclass: groupOfNames
cn: user
uniqueMember: uid=admin,ou=people,dc=springframework,dc=org
uniqueMember: uid=user,ou=people,dc=springframework,dc=org

dn: cn=admin,ou=groups,dc=springframework,dc=org
objectclass: top
objectclass: groupOfNames
cn: admin
uniqueMember: uid=admin,ou=people,dc=springframework,dc=org

You can define custom authentication by exposing a custom AuthenticationProvider as a bean. For example, the following will customize authentication assuming that SpringAuthenticationProvider implements AuthenticationProvider:

	Note
	This is only used if the AuthenticationManagerBuilder has not been populated

@Bean
public SpringAuthenticationProvider springAuthenticationProvider() {
	return new SpringAuthenticationProvider();
}

You can define custom authentication by exposing a custom UserDetailsService as a bean. For example, the following will customize authentication assuming that SpringDataUserDetailsService implements UserDetailsService:

	Note
	This is only used if the AuthenticationManagerBuilder has not been populated and no AuthenticationProviderBean is defined.

@Bean
public SpringDataUserDetailsService springDataUserDetailsService() {
	return new SpringDataUserDetailsService();
}

You can also customize how passwords are encoded by exposing a PasswordEncoder as a bean. For example, if you use bcrypt you can add a bean definition as shown below:

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

We can enable annotation-based security using the @EnableGlobalMethodSecurity annotation on any @Configuration instance. For example, the following would enable Spring Security’s @Secured annotation.

@EnableGlobalMethodSecurity(securedEnabled = true)
public class MethodSecurityConfig {
// ...
}

Adding an annotation to a method (on a class or interface) would then limit the access to that method accordingly. Spring Security’s native annotation support defines a set of attributes for the method. These will be passed to the AccessDecisionManager for it to make the actual decision:

public interface BankService {

@Secured("IS_AUTHENTICATED_ANONYMOUSLY")
public Account readAccount(Long id);

@Secured("IS_AUTHENTICATED_ANONYMOUSLY")
public Account[] findAccounts();

@Secured("ROLE_TELLER")
public Account post(Account account, double amount);
}

Support for JSR-250 annotations can be enabled using

@EnableGlobalMethodSecurity(jsr250Enabled = true)
public class MethodSecurityConfig {
// ...
}

These are standards-based and allow simple role-based constraints to be applied but do not have the power Spring Security’s native annotations. To use the new expression-based syntax, you would use

@EnableGlobalMethodSecurity(prePostEnabled = true)
public class MethodSecurityConfig {
// ...
}

and the equivalent Java code would be

public interface BankService {

@PreAuthorize("isAnonymous()")
public Account readAccount(Long id);

@PreAuthorize("isAnonymous()")
public Account[] findAccounts();

@PreAuthorize("hasAuthority('ROLE_TELLER')")
public Account post(Account account, double amount);
}

Sometimes you may need to perform operations that are more complicated than are possible with the @EnableGlobalMethodSecurity annotation allow. For these instances, you can extend the GlobalMethodSecurityConfiguration ensuring that the @EnableGlobalMethodSecurity annotation is present on your subclass. For example, if you wanted to provide a custom MethodSecurityExpressionHandler, you could use the following configuration:

@EnableGlobalMethodSecurity(prePostEnabled = true)
public class MethodSecurityConfig extends GlobalMethodSecurityConfiguration {
	@Override
	protected MethodSecurityExpressionHandler createExpressionHandler() {
		// ... create and return custom MethodSecurityExpressionHandler ...
		return expressionHandler;
	}
}

For additional information about methods that can be overridden, refer to the GlobalMethodSecurityConfiguration Javadoc.

Spring Security supports method security using Reactor’s Context which is setup using ReactiveSecurityContextHolder. For example, this demonstrates how to retrieve the currently logged in user’s message.

	Note
	For this to work the return type of the method must be a org.reactivestreams.Publisher (i.e. Mono/Flux). This is necessary to integrate with Reactor’s Context.

Authentication authentication = new TestingAuthenticationToken("user", "password", "ROLE_USER");

Mono<String> messageByUsername = ReactiveSecurityContextHolder.getContext()
	.map(SecurityContext::getAuthentication)
	.map(Authentication::getName)
	.flatMap(this::findMessageByUsername)
	// In a WebFlux application the `subscriberContext` is automatically setup using `ReactorContextWebFilter`
	.subscriberContext(ReactiveSecurityContextHolder.withAuthentication(authentication));

StepVerifier.create(messageByUsername)
	.expectNext("Hi user")
	.verifyComplete();

with this::findMessageByUsername defined as:

Mono<String> findMessageByUsername(String username) {
	return Mono.just("Hi " + username);
}

Below is a minimal method security configuration when using method security in reactive applications.

@EnableReactiveMethodSecurity
public class SecurityConfig {
	@Bean
	public MapReactiveUserDetailsService userDetailsService() {
		User.UserBuilder userBuilder = User.withDefaultPasswordEncoder();
		UserDetails rob = userBuilder.username("rob").password("rob").roles("USER").build();
		UserDetails admin = userBuilder.username("admin").password("admin").roles("USER","ADMIN").build();
		return new MapReactiveUserDetailsService(rob, admin);
	}
}

Consider the following class:

@Component
public class HelloWorldMessageService {
	@PreAuthorize("hasRole('ADMIN')")
	public Mono<String> findMessage() {
		return Mono.just("Hello World!");
	}
}

Combined with our configuration above, @PreAuthorize("hasRole('ADMIN')") will ensure that findByMessage is only invoked by a user with the role ADMIN. It is important to note that any of the expressions in standard method security work for @EnableReactiveMethodSecurity. However, at this time we only support return type of Boolean or boolean of the expression. This means that the expression must not block.

When integrating with Section 5.6, “WebFlux Security”, the Reactor Context is automatically established by Spring Security according to the authenticated user.

@EnableWebFluxSecurity
@EnableReactiveMethodSecurity
public class SecurityConfig {

	@Bean
	SecurityWebFilterChain springWebFilterChain(ServerHttpSecurity http) throws Exception {
		return http
			// Demonstrate that method security works
			// Best practice to use both for defense in depth
			.authorizeExchange()
				.anyExchange().permitAll()
				.and()
			.httpBasic().and()
			.build();
	}

	@Bean
	MapReactiveUserDetailsService userDetailsService() {
		User.UserBuilder userBuilder = User.withDefaultPasswordEncoder();
		UserDetails rob = userBuilder.username("rob").password("rob").roles("USER").build();
		UserDetails admin = userBuilder.username("admin").password("admin").roles("USER","ADMIN").build();
		return new MapReactiveUserDetailsService(rob, admin);
	}
}

You can find a complete sample in hellowebflux-method

The namespace is designed to capture the most common uses of the framework and provide a simplified and concise syntax for enabling them within an application. The design is based around the large-scale dependencies within the framework, and can be divided up into the following areas:

We’ll see how to configure these in the following sections.

The first thing you need to do is add the following filter declaration to your web.xml file:

<filter>
<filter-name>springSecurityFilterChain</filter-name>
<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>

<filter-mapping>
<filter-name>springSecurityFilterChain</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

This provides a hook into the Spring Security web infrastructure. DelegatingFilterProxy is a Spring Framework class which delegates to a filter implementation which is defined as a Spring bean in your application context. In this case, the bean is named "springSecurityFilterChain", which is an internal infrastructure bean created by the namespace to handle web security. Note that you should not use this bean name yourself. Once you’ve added this to your web.xml, you’re ready to start editing your application context file. Web security services are configured using the <http> element.

All you need to enable web security to begin with is

<http>
<intercept-url pattern="/**" access="hasRole('USER')" />
<form-login />
<logout />
</http>

Which says that we want all URLs within our application to be secured, requiring the role ROLE_USER to access them, we want to log in to the application using a form with username and password, and that we want a logout URL registered which will allow us to log out of the application. <http> element is the parent for all web-related namespace functionality. The <intercept-url> element defines a pattern which is matched against the URLs of incoming requests using an ant path style syntax ^[2]. You can also use regular-expression matching as an alternative (see the namespace appendix for more details). The access attribute defines the access requirements for requests matching the given pattern. With the default configuration, this is typically a comma-separated list of roles, one of which a user must have to be allowed to make the request. The prefix"ROLE_" is a marker which indicates that a simple comparison with the user’s authorities should be made. In other words, a normal role-based check should be used. Access-control in Spring Security is not limited to the use of simple roles (hence the use of the prefix to differentiate between different types of security attributes). We’ll see later how the interpretation can vary footnote:[The interpretation of the comma-separated values in the access attribute depends on the implementation of the –1— which is used. In Spring Security 3.0, the attribute can also be populated with an –2—.

	Note
	You can use multiple <intercept-url> elements to define different access requirements for different sets of URLs, but they will be evaluated in the order listed and the first match will be used. So you must put the most specific matches at the top. You can also add a method attribute to limit the match to a particular HTTP method (GET, POST, PUT etc.).

To add some users, you can define a set of test data directly in the namespace:

<authentication-manager>
<authentication-provider>
	<user-service>
	<!-- Password is prefixed with {noop} to indicate to DelegatingPasswordEncoder that
	NoOpPasswordEncoder should be used. This is not safe for production, but makes reading
	in samples easier. Normally passwords should be hashed using BCrypt -->
	<user name="jimi" password="{noop}jimispassword" authorities="ROLE_USER, ROLE_ADMIN" />
	<user name="bob" password="{noop}bobspassword" authorities="ROLE_USER" />
	</user-service>
</authentication-provider>
</authentication-manager>

This is an example of a secure way of storing the same passwords. The password is prefixed with {bcrypt} to instruct DelegatingPasswordEncoder, which supports any configured PasswordEncoder for matching, that the passwords are hashed using BCrypt:

<authentication-manager>
<authentication-provider>
	<user-service>
	<user name="jimi" password="{bcrypt}$2a$10$ddEWZUl8aU0GdZPPpy7wbu82dvEw/pBpbRvDQRqA41y6mK1CoH00m"
			authorities="ROLE_USER, ROLE_ADMIN" />
	<user name="bob" password="{bcrypt}$2a$10$/elFpMBnAYYig6KRR5bvOOYeZr1ie1hSogJryg9qDlhza4oCw1Qka"
			authorities="ROLE_USER" />
	<user name="jimi" password="{noop}jimispassword" authorities="ROLE_USER, ROLE_ADMIN" />
	<user name="bob" password="{noop}bobspassword" authorities="ROLE_USER" />
	</user-service>
</authentication-provider>
</authentication-manager>

The configuration above defines two users, their passwords and their roles within the application (which will be used for access control). It is also possible to load user information from a standard properties file using the properties attribute on user-service. See the section on in-memory authentication for more details on the file format. Using the <authentication-provider> element means that the user information will be used by the authentication manager to process authentication requests. You can have multiple <authentication-provider> elements to define different authentication sources and each will be consulted in turn.

At this point you should be able to start up your application and you will be required to log in to proceed. Try it out, or try experimenting with the "tutorial" sample application that comes with the project.

You might be wondering where the login form came from when you were prompted to log in, since we made no mention of any HTML files or JSPs. In fact, since we didn’t explicitly set a URL for the login page, Spring Security generates one automatically, based on the features that are enabled and using standard values for the URL which processes the submitted login, the default target URL the user will be sent to after logging in and so on. However, the namespace offers plenty of support to allow you to customize these options. For example, if you want to supply your own login page, you could use:

<http>
<intercept-url pattern="/login.jsp*" access="IS_AUTHENTICATED_ANONYMOUSLY"/>
<intercept-url pattern="/**" access="ROLE_USER" />
<form-login login-page='/login.jsp'/>
</http>

Also note that we’ve added an extra intercept-url element to say that any requests for the login page should be available to anonymous users ^[3] and also the AuthenticatedVoter class for more details on how the value IS_AUTHENTICATED_ANONYMOUSLY is processed.]. Otherwise the request would be matched by the pattern /** and it wouldn’t be possible to access the login page itself! This is a common configuration error and will result in an infinite loop in the application. Spring Security will emit a warning in the log if your login page appears to be secured. It is also possible to have all requests matching a particular pattern bypass the security filter chain completely, by defining a separate http element for the pattern like this:

<http pattern="/css/**" security="none"/>
<http pattern="/login.jsp*" security="none"/>

<http use-expressions="false">
<intercept-url pattern="/**" access="ROLE_USER" />
<form-login login-page='/login.jsp'/>
</http>

From Spring Security 3.1 it is now possible to use multiple http elements to define separate security filter chain configurations for different request patterns. If the pattern attribute is omitted from an http element, it matches all requests. Creating an unsecured pattern is a simple example of this syntax, where the pattern is mapped to an empty filter chain ^[4]. We’ll look at this new syntax in more detail in the chapter on the Security Filter Chain.

It’s important to realise that these unsecured requests will be completely oblivious to any Spring Security web-related configuration or additional attributes such as requires-channel, so you will not be able to access information on the current user or call secured methods during the request. Use access='IS_AUTHENTICATED_ANONYMOUSLY' as an alternative if you still want the security filter chain to be applied.

If you want to use basic authentication instead of form login, then change the configuration to

<http use-expressions="false">
<intercept-url pattern="/**" access="ROLE_USER" />
<http-basic />
</http>

Basic authentication will then take precedence and will be used to prompt for a login when a user attempts to access a protected resource. Form login is still available in this configuration if you wish to use it, for example through a login form embedded in another web page.

<http pattern="/login.htm*" security="none"/>
<http use-expressions="false">
<intercept-url pattern='/**' access='ROLE_USER' />
<form-login login-page='/login.htm' default-target-url='/home.htm'
		always-use-default-target='true' />
</http>

The logout element adds support for logging out by navigating to a particular URL. The default logout URL is /logout, but you can set it to something else using the logout-url attribute. More information on other available attributes may be found in the namespace appendix.

In practice you will need a more scalable source of user information than a few names added to the application context file. Most likely you will want to store your user information in something like a database or an LDAP server. LDAP namespace configuration is dealt with in the LDAP chapter, so we won’t cover it here. If you have a custom implementation of Spring Security’s UserDetailsService, called "myUserDetailsService" in your application context, then you can authenticate against this using

<authentication-manager>
	<authentication-provider user-service-ref='myUserDetailsService'/>
</authentication-manager>

If you want to use a database, then you can use

<authentication-manager>
<authentication-provider>
	<jdbc-user-service data-source-ref="securityDataSource"/>
</authentication-provider>
</authentication-manager>

Where "securityDataSource" is the name of a DataSource bean in the application context, pointing at a database containing the standard Spring Security user data tables. Alternatively, you could configure a Spring Security JdbcDaoImpl bean and point at that using the user-service-ref attribute:

<authentication-manager>
<authentication-provider user-service-ref='myUserDetailsService'/>
</authentication-manager>

<beans:bean id="myUserDetailsService"
	class="org.springframework.security.core.userdetails.jdbc.JdbcDaoImpl">
<beans:property name="dataSource" ref="dataSource"/>
</beans:bean>

You can also use standard AuthenticationProvider beans as follows

<authentication-manager>
	<authentication-provider ref='myAuthenticationProvider'/>
</authentication-manager>

where myAuthenticationProvider is the name of a bean in your application context which implements AuthenticationProvider. You can use multiple authentication-provider elements, in which case the providers will be queried in the order they are declared. See Section 6.6, “The Authentication Manager and the Namespace” for more information on how the Spring Security AuthenticationManager is configured using the namespace.

<beans:bean name="bcryptEncoder"
	class="org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder"/>

<authentication-manager>
<authentication-provider>
	<password-encoder ref="bcryptEncoder"/>
	<user-service>
	<user name="jimi" password="$2a$10$ddEWZUl8aU0GdZPPpy7wbu82dvEw/pBpbRvDQRqA41y6mK1CoH00m"
			authorities="ROLE_USER, ROLE_ADMIN" />
	<user name="bob" password="$2a$10$/elFpMBnAYYig6KRR5bvOOYeZr1ie1hSogJryg9qDlhza4oCw1Qka"
			authorities="ROLE_USER" />
	</user-service>
</authentication-provider>
</authentication-manager>

See the separate Remember-Me chapter for information on remember-me namespace configuration.

If your application supports both HTTP and HTTPS, and you require that particular URLs can only be accessed over HTTPS, then this is directly supported using the requires-channel attribute on <intercept-url>:

<http>
<intercept-url pattern="/secure/**" access="ROLE_USER" requires-channel="https"/>
<intercept-url pattern="/**" access="ROLE_USER" requires-channel="any"/>
...
</http>

With this configuration in place, if a user attempts to access anything matching the "/secure/**" pattern using HTTP, they will first be redirected to an HTTPS URL ^[5]. The available options are "http", "https" or "any". Using the value "any" means that either HTTP or HTTPS can be used.

If your application uses non-standard ports for HTTP and/or HTTPS, you can specify a list of port mappings as follows:

<http>
...
<port-mappings>
	<port-mapping http="9080" https="9443"/>
</port-mappings>
</http>

Note that in order to be truly secure, an application should not use HTTP at all or switch between HTTP and HTTPS. It should start in HTTPS (with the user entering an HTTPS URL) and use a secure connection throughout to avoid any possibility of man-in-the-middle attacks.

The namespace supports OpenID login either instead of, or in addition to normal form-based login, with a simple change:

<http>
<intercept-url pattern="/**" access="ROLE_USER" />
<openid-login />
</http>

You should then register yourself with an OpenID provider (such as myopenid.com), and add the user information to your in-memory <user-service>:

<user name="http://jimi.hendrix.myopenid.com/" authorities="ROLE_USER" />

You should be able to login using the myopenid.com site to authenticate. It is also possible to select a specific UserDetailsService bean for use OpenID by setting the user-service-ref attribute on the openid-login element. See the previous section on authentication providers for more information. Note that we have omitted the password attribute from the above user configuration, since this set of user data is only being used to load the authorities for the user. A random password will be generated internally, preventing you from accidentally using this user data as an authentication source elsewhere in your configuration.

<openid-login>
<attribute-exchange>
	<openid-attribute name="email" type="http://axschema.org/contact/email" required="true"/>
	<openid-attribute name="name" type="http://axschema.org/namePerson"/>
</attribute-exchange>
</openid-login>

OpenIDAuthenticationToken token =
	(OpenIDAuthenticationToken)SecurityContextHolder.getContext().getAuthentication();
List<OpenIDAttribute> attributes = token.getAttributes();

For additional information on how to customize the headers element refer to the Chapter 21, Security HTTP Response Headers section of the reference.

If you’ve used Spring Security before, you’ll know that the framework maintains a chain of filters in order to apply its services. You may want to add your own filters to the stack at particular locations or use a Spring Security filter for which there isn’t currently a namespace configuration option (CAS, for example). Or you might want to use a customized version of a standard namespace filter, such as the UsernamePasswordAuthenticationFilter which is created by the <form-login> element, taking advantage of some of the extra configuration options which are available by using the bean explicitly. How can you do this with namespace configuration, since the filter chain is not directly exposed?

The order of the filters is always strictly enforced when using the namespace. When the application context is being created, the filter beans are sorted by the namespace handling code and the standard Spring Security filters each have an alias in the namespace and a well-known position.

Note

In previous versions, the sorting took place after the filter instances had been created, during post-processing of the application context. In version 3.0+ the sorting is now done at the bean metadata level, before the classes have been instantiated. This has implications for how you add your own filters to the stack as the entire filter list must be known during the parsing of the <http> element, so the syntax has changed slightly in 3.0.

The filters, aliases and namespace elements/attributes which create the filters are shown in Table 6.1, “Standard Filter Aliases and Ordering”. The filters are listed in the order in which they occur in the filter chain.

You can add your own filter to the stack, using the custom-filter element and one of these names to specify the position your filter should appear at:

<http>
<custom-filter position="FORM_LOGIN_FILTER" ref="myFilter" />
</http>

<beans:bean id="myFilter" class="com.mycompany.MySpecialAuthenticationFilter"/>

You can also use the after or before attributes if you want your filter to be inserted before or after another filter in the stack. The names "FIRST" and "LAST" can be used with the position attribute to indicate that you want your filter to appear before or after the entire stack, respectively.

Avoiding filter position conflicts

If you are inserting a custom filter which may occupy the same position as one of the standard filters created by the namespace then it’s important that you don’t include the namespace versions by mistake. Remove any elements which create filters whose functionality you want to replace. Note that you can’t replace filters which are created by the use of the <http> element itself - SecurityContextPersistenceFilter, ExceptionTranslationFilter or FilterSecurityInterceptor. Some other filters are added by default, but you can disable them. An AnonymousAuthenticationFilter is added by default and unless you have session-fixation protection disabled, a SessionManagementFilter will also be added to the filter chain.

If you’re replacing a namespace filter which requires an authentication entry point (i.e. where the authentication process is triggered by an attempt by an unauthenticated user to access to a secured resource), you will need to add a custom entry point bean too.

This element is used to enable annotation-based security in your application (by setting the appropriate attributes on the element), and also to group together security pointcut declarations which will be applied across your entire application context. You should only declare one <global-method-security> element. The following declaration would enable support for Spring Security’s @Secured:

<global-method-security secured-annotations="enabled" />

Adding an annotation to a method (on an class or interface) would then limit the access to that method accordingly. Spring Security’s native annotation support defines a set of attributes for the method. These will be passed to the AccessDecisionManager for it to make the actual decision:

public interface BankService {

@Secured("IS_AUTHENTICATED_ANONYMOUSLY")
public Account readAccount(Long id);

@Secured("IS_AUTHENTICATED_ANONYMOUSLY")
public Account[] findAccounts();

@Secured("ROLE_TELLER")
public Account post(Account account, double amount);
}

Support for JSR-250 annotations can be enabled using

<global-method-security jsr250-annotations="enabled" />

These are standards-based and allow simple role-based constraints to be applied but do not have the power Spring Security’s native annotations. To use the new expression-based syntax, you would use

<global-method-security pre-post-annotations="enabled" />

and the equivalent Java code would be

public interface BankService {

@PreAuthorize("isAnonymous()")
public Account readAccount(Long id);

@PreAuthorize("isAnonymous()")
public Account[] findAccounts();

@PreAuthorize("hasAuthority('ROLE_TELLER')")
public Account post(Account account, double amount);
}

Expression-based annotations are a good choice if you need to define simple rules that go beyond checking the role names against the user’s list of authorities.

	Note
	The annotated methods will only be secured for instances which are defined as Spring beans (in the same application context in which method-security is enabled). If you want to secure instances which are not created by Spring (using the new operator, for example) then you need to use AspectJ.

	Note
	You can enable more than one type of annotation in the same application, but only one type should be used for any interface or class as the behaviour will not be well-defined otherwise. If two annotations are found which apply to a particular method, then only one of them will be applied.

<global-method-security>
<protect-pointcut expression="execution(* com.mycompany.*Service.*(..))"
	access="ROLE_USER"/>
</global-method-security>

If you need to use a more complicated access control strategy then it is easy to set an alternative for both method and web security.

For method security, you do this by setting the access-decision-manager-ref attribute on global-method-security to the id of the appropriate AccessDecisionManager bean in the application context:

<global-method-security access-decision-manager-ref="myAccessDecisionManagerBean">
...
</global-method-security>

The syntax for web security is the same, but on the http element:

<http access-decision-manager-ref="myAccessDecisionManagerBean">
...
</http>

The most fundamental object is SecurityContextHolder. This is where we store details of the present security context of the application, which includes details of the principal currently using the application. By default the SecurityContextHolder uses a ThreadLocal to store these details, which means that the security context is always available to methods in the same thread of execution, even if the security context is not explicitly passed around as an argument to those methods. Using a ThreadLocal in this way is quite safe if care is taken to clear the thread after the present principal’s request is processed. Of course, Spring Security takes care of this for you automatically so there is no need to worry about it.

Some applications aren’t entirely suitable for using a ThreadLocal, because of the specific way they work with threads. For example, a Swing client might want all threads in a Java Virtual Machine to use the same security context. SecurityContextHolder can be configured with a strategy on startup to specify how you would like the context to be stored. For a standalone application you would use the SecurityContextHolder.MODE_GLOBAL strategy. Other applications might want to have threads spawned by the secure thread also assume the same security identity. This is achieved by using SecurityContextHolder.MODE_INHERITABLETHREADLOCAL. You can change the mode from the default SecurityContextHolder.MODE_THREADLOCAL in two ways. The first is to set a system property, the second is to call a static method on SecurityContextHolder. Most applications won’t need to change from the default, but if you do, take a look at the JavaDoc for SecurityContextHolder to learn more.

Object principal = SecurityContextHolder.getContext().getAuthentication().getPrincipal();

if (principal instanceof UserDetails) {
String username = ((UserDetails)principal).getUsername();
} else {
String username = principal.toString();
}

Another item to note from the above code fragment is that you can obtain a principal from the Authentication object. The principal is just an Object. Most of the time this can be cast into a UserDetails object. UserDetails is a core interface in Spring Security. It represents a principal, but in an extensible and application-specific way. Think of UserDetails as the adapter between your own user database and what Spring Security needs inside the SecurityContextHolder. Being a representation of something from your own user database, quite often you will cast the UserDetails to the original object that your application provided, so you can call business-specific methods (like getEmail(), getEmployeeNumber() and so on).

By now you’re probably wondering, so when do I provide a UserDetails object? How do I do that? I thought you said this thing was declarative and I didn’t need to write any Java code - what gives? The short answer is that there is a special interface called UserDetailsService. The only method on this interface accepts a String-based username argument and returns a UserDetails:

UserDetails loadUserByUsername(String username) throws UsernameNotFoundException;

This is the most common approach to loading information for a user within Spring Security and you will see it used throughout the framework whenever information on a user is required.

On successful authentication, UserDetails is used to build the Authentication object that is stored in the SecurityContextHolder (more on this below). The good news is that we provide a number of UserDetailsService implementations, including one that uses an in-memory map (InMemoryDaoImpl) and another that uses JDBC (JdbcDaoImpl). Most users tend to write their own, though, with their implementations often simply sitting on top of an existing Data Access Object (DAO) that represents their employees, customers, or other users of the application. Remember the advantage that whatever your UserDetailsService returns can always be obtained from the SecurityContextHolder using the above code fragment.

Note

There is often some confusion about UserDetailsService. It is purely a DAO for user data and performs no other function other than to supply that data to other components within the framework. In particular, it does not authenticate the user, which is done by the AuthenticationManager. In many cases it makes more sense to implement AuthenticationProvider directly if you require a custom authentication process.

Besides the principal, another important method provided by Authentication is getAuthorities(). This method provides an array of GrantedAuthority objects. A GrantedAuthority is, not surprisingly, an authority that is granted to the principal. Such authorities are usually "roles", such as ROLE_ADMINISTRATOR or ROLE_HR_SUPERVISOR. These roles are later on configured for web authorization, method authorization and domain object authorization. Other parts of Spring Security are capable of interpreting these authorities, and expect them to be present. GrantedAuthority objects are usually loaded by the UserDetailsService.

Usually the GrantedAuthority objects are application-wide permissions. They are not specific to a given domain object. Thus, you wouldn’t likely have a GrantedAuthority to represent a permission to Employee object number 54, because if there are thousands of such authorities you would quickly run out of memory (or, at the very least, cause the application to take a long time to authenticate a user). Of course, Spring Security is expressly designed to handle this common requirement, but you’d instead use the project’s domain object security capabilities for this purpose.

Just to recap, the major building blocks of Spring Security that we’ve seen so far are:

Now that you’ve gained an understanding of these repeatedly-used components, let’s take a closer look at the process of authentication.

Let’s consider a standard authentication scenario that everyone is familiar with.

The first three items constitute the authentication process so we’ll take a look at how these take place within Spring Security.

From that point on, the user is considered to be authenticated. Let’s look at some code as an example.

import org.springframework.security.authentication.*;
import org.springframework.security.core.*;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.context.SecurityContextHolder;

public class AuthenticationExample {
private static AuthenticationManager am = new SampleAuthenticationManager();

public static void main(String[] args) throws Exception {
	BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

	while(true) {
	System.out.println("Please enter your username:");
	String name = in.readLine();
	System.out.println("Please enter your password:");
	String password = in.readLine();
	try {
		Authentication request = new UsernamePasswordAuthenticationToken(name, password);
		Authentication result = am.authenticate(request);
		SecurityContextHolder.getContext().setAuthentication(result);
		break;
	} catch(AuthenticationException e) {
		System.out.println("Authentication failed: " + e.getMessage());
	}
	}
	System.out.println("Successfully authenticated. Security context contains: " +
			SecurityContextHolder.getContext().getAuthentication());
}
}

class SampleAuthenticationManager implements AuthenticationManager {
static final List<GrantedAuthority> AUTHORITIES = new ArrayList<GrantedAuthority>();

static {
	AUTHORITIES.add(new SimpleGrantedAuthority("ROLE_USER"));
}

public Authentication authenticate(Authentication auth) throws AuthenticationException {
	if (auth.getName().equals(auth.getCredentials())) {
	return new UsernamePasswordAuthenticationToken(auth.getName(),
		auth.getCredentials(), AUTHORITIES);
	}
	throw new BadCredentialsException("Bad Credentials");
}
}

Here we have written a little program that asks the user to enter a username and password and performs the above sequence. The AuthenticationManager which we’ve implemented here will authenticate any user whose username and password are the same. It assigns a single role to every user. The output from the above will be something like:

Please enter your username:
bob
Please enter your password:
password
Authentication failed: Bad Credentials
Please enter your username:
bob
Please enter your password:
bob
Successfully authenticated. Security context contains: \
org.springframework.security.authentication.UsernamePasswordAuthenticationToken@441d0230: \
Principal: bob; Password: [PROTECTED]; \
Authenticated: true; Details: null; \
Granted Authorities: ROLE_USER

Note that you don’t normally need to write any code like this. The process will normally occur internally, in a web authentication filter for example. We’ve just included the code here to show that the question of what actually constitutes authentication in Spring Security has quite a simple answer. A user is authenticated when the SecurityContextHolder contains a fully populated Authentication object.

In fact, Spring Security doesn’t mind how you put the Authentication object inside the SecurityContextHolder. The only critical requirement is that the SecurityContextHolder contains an Authentication which represents a principal before the AbstractSecurityInterceptor (which we’ll see more about later) needs to authorize a user operation.

You can (and many users do) write their own filters or MVC controllers to provide interoperability with authentication systems that are not based on Spring Security. For example, you might be using Container-Managed Authentication which makes the current user available from a ThreadLocal or JNDI location. Or you might work for a company that has a legacy proprietary authentication system, which is a corporate "standard" over which you have little control. In situations like this it’s quite easy to get Spring Security to work, and still provide authorization capabilities. All you need to do is write a filter (or equivalent) that reads the third-party user information from a location, build a Spring Security-specific Authentication object, and put it into the SecurityContextHolder. In this case you also need to think about things which are normally taken care of automatically by the built-in authentication infrastructure. For example, you might need to pre-emptively create an HTTP session to cache the context between requests, before you write the response to the client footnote:[It isn’t possible to create a session once the response has been committed.

If you’re wondering how the AuthenticationManager is implemented in a real world example, we’ll look at that in the core services chapter.

ExceptionTranslationFilter is a Spring Security filter that has responsibility for detecting any Spring Security exceptions that are thrown. Such exceptions will generally be thrown by an AbstractSecurityInterceptor, which is the main provider of authorization services. We will discuss AbstractSecurityInterceptor in the next section, but for now we just need to know that it produces Java exceptions and knows nothing about HTTP or how to go about authenticating a principal. Instead the ExceptionTranslationFilter offers this service, with specific responsibility for either returning error code 403 (if the principal has been authenticated and therefore simply lacks sufficient access - as per step seven above), or launching an AuthenticationEntryPoint (if the principal has not been authenticated and therefore we need to go commence step three).

The AuthenticationEntryPoint is responsible for step three in the above list. As you can imagine, each web application will have a default authentication strategy (well, this can be configured like nearly everything else in Spring Security, but let’s keep it simple for now). Each major authentication system will have its own AuthenticationEntryPoint implementation, which typically performs one of the actions described in step 3.

Once your browser submits your authentication credentials (either as an HTTP form post or HTTP header) there needs to be something on the server that "collects" these authentication details. By now we’re at step six in the above list. In Spring Security we have a special name for the function of collecting authentication details from a user agent (usually a web browser), referring to it as the "authentication mechanism". Examples are form-base login and Basic authentication. Once the authentication details have been collected from the user agent, an Authentication "request" object is built and then presented to the AuthenticationManager.

After the authentication mechanism receives back the fully-populated Authentication object, it will deem the request valid, put the Authentication into the SecurityContextHolder, and cause the original request to be retried (step seven above). If, on the other hand, the AuthenticationManager rejected the request, the authentication mechanism will ask the user agent to retry (step two above).

Depending on the type of application, there may need to be a strategy in place to store the security context between user operations. In a typical web application, a user logs in once and is subsequently identified by their session Id. The server caches the principal information for the duration session. In Spring Security, the responsibility for storing the SecurityContext between requests falls to the SecurityContextPersistenceFilter, which by default stores the context as an HttpSession attribute between HTTP requests. It restores the context to the SecurityContextHolder for each request and, crucially, clears the SecurityContextHolder when the request completes. You shouldn’t interact directly with the HttpSession for security purposes. There is simply no justification for doing so - always use the SecurityContextHolder instead.

Many other types of application (for example, a stateless RESTful web service) do not use HTTP sessions and will re-authenticate on every request. However, it is still important that the SecurityContextPersistenceFilter is included in the chain to make sure that the SecurityContextHolder is cleared after each request.

Note

In an application which receives concurrent requests in a single session, the same SecurityContext instance will be shared between threads. Even though a ThreadLocal is being used, it is the same instance that is retrieved from the HttpSession for each thread. This has implications if you wish to temporarily change the context under which a thread is running. If you just use SecurityContextHolder.getContext(), and call setAuthentication(anAuthentication) on the returned context object, then the Authentication object will change in all concurrent threads which share the same SecurityContext instance. You can customize the behaviour of SecurityContextPersistenceFilter to create a completely new SecurityContext for each request, preventing changes in one thread from affecting another. Alternatively you can create a new instance just at the point where you temporarily change the context. The method SecurityContextHolder.createEmptyContext() always returns a new context instance.

If you’re familiar with AOP, you’d be aware there are different types of advice available: before, after, throws and around. An around advice is very useful, because an advisor can elect whether or not to proceed with a method invocation, whether or not to modify the response, and whether or not to throw an exception. Spring Security provides an around advice for method invocations as well as web requests. We achieve an around advice for method invocations using Spring’s standard AOP support and we achieve an around advice for web requests using a standard Filter.

For those not familiar with AOP, the key point to understand is that Spring Security can help you protect method invocations as well as web requests. Most people are interested in securing method invocations on their services layer. This is because the services layer is where most business logic resides in current-generation Java EE applications. If you just need to secure method invocations in the services layer, Spring’s standard AOP will be adequate. If you need to secure domain objects directly, you will likely find that AspectJ is worth considering.

You can elect to perform method authorization using AspectJ or Spring AOP, or you can elect to perform web request authorization using filters. You can use zero, one, two or three of these approaches together. The mainstream usage pattern is to perform some web request authorization, coupled with some Spring AOP method invocation authorization on the services layer.

So what is a "secure object" anyway? Spring Security uses the term to refer to any object that can have security (such as an authorization decision) applied to it. The most common examples are method invocations and web requests.

Each supported secure object type has its own interceptor class, which is a subclass of AbstractSecurityInterceptor. Importantly, by the time the AbstractSecurityInterceptor is called, the SecurityContextHolder will contain a valid Authentication if the principal has been authenticated.

AbstractSecurityInterceptor provides a consistent workflow for handling secure object requests, typically:

AfterInvocationManager

Following the secure object invocation proceeding and then returning - which may mean a method invocation completing or a filter chain proceeding - the AbstractSecurityInterceptor gets one final chance to handle the invocation. At this stage the AbstractSecurityInterceptor is interested in possibly modifying the return object. We might want this to happen because an authorization decision couldn’t be made "on the way in" to a secure object invocation. Being highly pluggable, AbstractSecurityInterceptor will pass control to an AfterInvocationManager to actually modify the object if needed. This class can even entirely replace the object, or throw an exception, or not change it in any way as it chooses. The after-invocation checks will only be executed if the invocation is successful. If an exception occurs, the additional checks will be skipped.

AbstractSecurityInterceptor and its related objects are shown in Figure 9.1, “Security interceptors and the "secure object" model”

Figure 9.1. Security interceptors and the "secure object" model

By default (from Spring Security 3.1 onwards) the ProviderManager will attempt to clear any sensitive credentials information from the Authentication object which is returned by a successful authentication request. This prevents information like passwords being retained longer than necessary.

This may cause issues when you are using a cache of user objects, for example, to improve performance in a stateless application. If the Authentication contains a reference to an object in the cache (such as a UserDetails instance) and this has its credentials removed, then it will no longer be possible to authenticate against the cached value. You need to take this into account if you are using a cache. An obvious solution is to make a copy of the object first, either in the cache implementation or in the AuthenticationProvider which creates the returned Authentication object. Alternatively, you can disable the eraseCredentialsAfterAuthentication property on ProviderManager. See the Javadoc for more information.

The simplest AuthenticationProvider implemented by Spring Security is DaoAuthenticationProvider, which is also one of the earliest supported by the framework. It leverages a UserDetailsService (as a DAO) in order to lookup the username, password and GrantedAuthority s. It authenticates the user simply by comparing the password submitted in a UsernamePasswordAuthenticationToken against the one loaded by the UserDetailsService. Configuring the provider is quite simple:

<bean id="daoAuthenticationProvider"
	class="org.springframework.security.authentication.dao.DaoAuthenticationProvider">
<property name="userDetailsService" ref="inMemoryDaoImpl"/>
<property name="passwordEncoder" ref="passwordEncoder"/>
</bean>

The PasswordEncoder is optional. A PasswordEncoder provides encoding and decoding of passwords presented in the UserDetails object that is returned from the configured UserDetailsService. This will be discussed in more detail below.

Is easy to use create a custom UserDetailsService implementation that extracts information from a persistence engine of choice, but many applications do not require such complexity. This is particularly true if you’re building a prototype application or just starting integrating Spring Security, when you don’t really want to spend time configuring databases or writing UserDetailsService implementations. For this sort of situation, a simple option is to use the user-service element from the security namespace:

<user-service id="userDetailsService">
<!-- Password is prefixed with {noop} to indicate to DelegatingPasswordEncoder that
NoOpPasswordEncoder should be used. This is not safe for production, but makes reading
in samples easier. Normally passwords should be hashed using BCrypt -->
<user name="jimi" password="{noop}jimispassword" authorities="ROLE_USER, ROLE_ADMIN" />
<user name="bob" password="{noop}bobspassword" authorities="ROLE_USER" />
</user-service>

This also supports the use of an external properties file:

<user-service id="userDetailsService" properties="users.properties"/>

The properties file should contain entries in the form

username=password,grantedAuthority[,grantedAuthority][,enabled|disabled]

For example

jimi=jimispassword,ROLE_USER,ROLE_ADMIN,enabled
bob=bobspassword,ROLE_USER,enabled

Spring Security also includes a UserDetailsService that can obtain authentication information from a JDBC data source. Internally Spring JDBC is used, so it avoids the complexity of a fully-featured object relational mapper (ORM) just to store user details. If your application does use an ORM tool, you might prefer to write a custom UserDetailsService to reuse the mapping files you’ve probably already created. Returning to JdbcDaoImpl, an example configuration is shown below:

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="org.hsqldb.jdbcDriver"/>
<property name="url" value="jdbc:hsqldb:hsql://localhost:9001"/>
<property name="username" value="sa"/>
<property name="password" value=""/>
</bean>

<bean id="userDetailsService"
	class="org.springframework.security.core.userdetails.jdbc.JdbcDaoImpl">
<property name="dataSource" ref="dataSource"/>
</bean>

You can use different relational database management systems by modifying the DriverManagerDataSource shown above. You can also use a global data source obtained from JNDI, as with any other Spring configuration.

Throughout the years the standard mechanism for storing passwords has evolved. In the beginning passwords were stored in plain text. The passwords were assumed to be safe because the data store the passwords were saved in required credentials to access it. However, malicious users were able to find ways to get large "data dumps" of usernames and passwords using attacks like SQL Injection. As more and more user credentials became public security experts realized we needed to do more to protect users passwords.

Developers were then encouraged to store passwords after running them through a one way hash such as SHA-256. When a user tried to authenticate, the hashed password would be compared to the hash of the password that they typed. This meant that the system only needed to store the one way hash of the password. If a breach occurred, then only the one way hashes of the passwords were exposed. Since the hashes were one way and it was computationally difficult to guess the passwords given the hash, it would not be worth the effort to figure out each password in the system. To defeat this new system malicious users decided to create lookup tables known as Rainbow Tables. Rather than doing the work of guessing each password every time, they computed the password once and stored it in a lookup table.

To mitigate the effectiveness of Rainbow Tables, developers were encouraged to use salted passwords. Instead of using just the password as input to the hash function, random bytes (known as salt) would be generated for every users' password. The salt and the user’s password would be ran through the hash function which produced a unique hash. The salt would be stored alongside the user’s password in clear text. Then when a user tried to authenticate, the hashed password would be compared to the hash of the stored salt and the password that they typed. The unique salt meant that Rainbow Tables were no longer effective because the hash was different for every salt and password combination.

In modern times we realize that cryptographic hashes (like SHA-256) are no longer secure. The reason is that with modern hardware we can perform billions of hash calculations a second. This means that we can crack each password individually with ease.

Developers are now encouraged to leverage adaptive one-way functions to store a password. Validation of passwords with adaptive one-way functions are intentionally resource (i.e. CPU, memory, etc) intensive. An adaptive one-way function allows configuring a "work factor" which can grow as hardware gets better. It is recommended that the "work factor" be tuned to take about 1 second to verify a password on your system. This trade off is to make it difficult for attackers to crack the password, but not so costly it puts excessive burden on your own system. Spring Security has attempted to provide a good starting point for the "work factor", but users are encouraged to customize the "work factor" for their own system since the performance will vary drastically from system to system. Examples of adaptive one-way functions that should be used include bcrypt, PBKDF2, scrypt, and Argon2.

Because adaptive one-way functions are intentionally resource intensive, validating a username and password for every request will degrade performance of an application significantly. There is nothing Spring Security (or any other library) can do to speed up the validation of the password since security is gained by making the validation resource intensive. Users are encouraged to exchange the long term credentials (i.e. username and password) for a short term credential (i.e. session, OAuth Token, etc). The short term credential can be validated quickly without any loss in security.

Prior to Spring Security 5.0 the default PasswordEncoder was NoOpPasswordEncoder which required plain text passwords. Based upon the Password History section you might expect that the default PasswordEncoder is now something like BCryptPasswordEncoder. However, this ignores three real world problems:

Instead Spring Security introduces DelegatingPasswordEncoder which solves all of the problems by:

You can easily construct an instance of DelegatingPasswordEncoder using PasswordEncoderFactories.

PasswordEncoder passwordEncoder =
    PasswordEncoderFactories.createDelegatingPasswordEncoder();

Alternatively, you may create your own custom instance. For example:

String idForEncode = "bcrypt";
Map encoders = new HashMap<>();
encoders.put(idForEncode, new BCryptPasswordEncoder());
encoders.put("noop", NoOpPasswordEncoder.getInstance());
encoders.put("pbkdf2", new Pbkdf2PasswordEncoder());
encoders.put("scrypt", new SCryptPasswordEncoder());
encoders.put("sha256", new StandardPasswordEncoder());

PasswordEncoder passwordEncoder =
    new DelegatingPasswordEncoder(idForEncode, encoders);

Password Storage Format

The general format for a password is:

{id}encodedPassword

Such that id is an identifier used to look up which PasswordEncoder should be used and encodedPassword is the original encoded password for the selected PasswordEncoder. The id must be at the beginning of the password, start with { and end with }. If the id cannot be found, the id will be null. For example, the following might be a list of passwords encoded using different id. All of the original passwords are "password".

{bcrypt}$2a$10$dXJ3SW6G7P50lGmMkkmwe.20cQQubK3.HZWzG3YB1tlRy.fqvM/BG 
{noop}password 
{pbkdf2}5d923b44a6d129f3ddf3e3c8d29412723dcbde72445e8ef6bf3b508fbf17fa4ed4d6b99ca763d8dc 
{scrypt}$e0801$8bWJaSu2IKSn9Z9kM+TPXfOc/9bdYSrN1oD9qfVThWEwdRTnO7re7Ei+fUZRJ68k9lTyuTeUp4of4g24hHnazw==$OAOec05+bXxvuu/1qZ6NUR+xQYvYv7BeL1QxwRpY5Pc=  
{sha256}97cde38028ad898ebc02e690819fa220e88c62e0699403e94fff291cfffaf8410849f27605abcbc0 

	The first password would have a PasswordEncoder id of bcrypt and encodedPassword of $2a$10$dXJ3SW6G7P50lGmMkkmwe.20cQQubK3.HZWzG3YB1tlRy.fqvM/BG. When matching it would delegate to BCryptPasswordEncoder
	The second password would have a PasswordEncoder id of noop and encodedPassword of password. When matching it would delegate to NoOpPasswordEncoder
	The third password would have a PasswordEncoder id of pbkdf2 and encodedPassword of 5d923b44a6d129f3ddf3e3c8d29412723dcbde72445e8ef6bf3b508fbf17fa4ed4d6b99ca763d8dc. When matching it would delegate to Pbkdf2PasswordEncoder
	The fourth password would have a PasswordEncoder id of scrypt and encodedPassword of $e0801$8bWJaSu2IKSn9Z9kM+TPXfOc/9bdYSrN1oD9qfVThWEwdRTnO7re7Ei+fUZRJ68k9lTyuTeUp4of4g24hHnazw==$OAOec05+bXxvuu/1qZ6NUR+xQYvYv7BeL1QxwRpY5Pc= When matching it would delegate to SCryptPasswordEncoder
	The final password would have a PasswordEncoder id of sha256 and encodedPassword of 97cde38028ad898ebc02e690819fa220e88c62e0699403e94fff291cfffaf8410849f27605abcbc0. When matching it would delegate to StandardPasswordEncoder

	Note
	Some users might be concerned that the storage format is provided for a potential hacker. This is not a concern because the storage of the password does not rely on the algorithm being a secret. Additionally, most formats are easy for an attacker to figure out without the prefix. For example, BCrypt passwords often start with $2a$.

{bcrypt}$2a$10$dXJ3SW6G7P50lGmMkkmwe.20cQQubK3.HZWzG3YB1tlRy.fqvM/BG

User user = User.withDefaultPasswordEncoder()
  .username("user")
  .password("password")
  .roles("user")
  .build();
System.out.println(user.getPassword());
// {bcrypt}$2a$10$dXJ3SW6G7P50lGmMkkmwe.20cQQubK3.HZWzG3YB1tlRy.fqvM/BG

UserBuilder users = User.withDefaultPasswordEncoder();
User user = users
  .username("user")
  .password("password")
  .roles("USER")
  .build();
User admin = users
  .username("admin")
  .password("password")
  .roles("USER","ADMIN")
  .build();

Troubleshooting

The following error occurs when one of the passwords that are stored has no id as described in the section called “Password Storage Format”.

java.lang.IllegalArgumentException: There is no PasswordEncoder mapped for the id "null"
	at org.springframework.security.crypto.password.DelegatingPasswordEncoder$UnmappedIdPasswordEncoder.matches(DelegatingPasswordEncoder.java:233)
	at org.springframework.security.crypto.password.DelegatingPasswordEncoder.matches(DelegatingPasswordEncoder.java:196)

The easiest way to resolve the error is to switch to explicitly provide the PasswordEncoder that you passwords are encoded with. The easiest way to resolve it is to figure out how your passwords are currently being stored and explicitly provide the correct PasswordEncoder. If you are migrating from Spring Security 4.2.x you can revert to the previous behavior by exposing a NoOpPasswordEncoder bean. For example, if you are using Java Configuration, you can create a configuration that looks like:

	Warning
	Reverting to NoOpPasswordEncoder is not considered to be secure. You should instead migrate to using DelegatingPasswordEncoder to support secure password encoding.

@Bean
public static NoOpPasswordEncoder passwordEncoder() {
    return NoOpPasswordEncoder.getInstance();
}

if you are using XML configuration, you can expose a PasswordEncoder with the id passwordEncoder:

<b:bean id="passwordEncoder"
        class="org.springframework.security.crypto.password.NoOpPasswordEncoder" factory-method="getInstance"/>

Alternatively, you can prefix all of your passwords with the correct id and continue to use DelegatingPasswordEncoder. For example, if you are using BCrypt, you would migrate your password from something like:

$2a$10$dXJ3SW6G7P50lGmMkkmwe.20cQQubK3.HZWzG3YB1tlRy.fqvM/BG

to

{bcrypt}$2a$10$dXJ3SW6G7P50lGmMkkmwe.20cQQubK3.HZWzG3YB1tlRy.fqvM/BG

For a complete listing of the mappings refer to the Javadoc on PasswordEncoderFactories.

The BCryptPasswordEncoder implementation uses the widely supported bcrypt algorithm to hash the passwords. In order to make it more resistent to password cracking, bcrypt is deliberately slow. Like other adaptive one-way functions, it should be tuned to take about 1 second to verify a password on your system.

// Create an encoder with strength 16
BCryptPasswordEncoder encoder = new BCryptPasswordEncoder(16);
String result = encoder.encode("myPassword");
assertTrue(encoder.matches("myPassword", result));

The Pbkdf2PasswordEncoder implementation uses the PBKDF2 algorithm to hash the passwords. In order to defeat password cracking PBKDF2 is a deliberately slow algorithm. Like other adaptive one-way functions, it should be tuned to take about 1 second to verify a password on your system. This algorithm is a good choice when FIPS certification is required.

// Create an encoder with all the defaults
Pbkdf2PasswordEncoder encoder = new Pbkdf2PasswordEncoder();
String result = encoder.encode("myPassword");
assertTrue(encoder.matches("myPassword", result));

The SCryptPasswordEncoder implementation uses scrypt algorithm to hash the passwords. In order to defeat password cracking on custom hardware scrypt is a deliberately slow algorithm that requires large amounts of memory. Like other adaptive one-way functions, it should be tuned to take about 1 second to verify a password on your system.

// Create an encoder with all the defaults
SCryptPasswordEncoder encoder = new SCryptPasswordEncoder();
String result = encoder.encode("myPassword");
assertTrue(encoder.matches("myPassword", result));

There are a significant number of other PasswordEncoder implementations that exist entirely for backward compatibility. They are all deprecated to indicate that they are no longer considered secure. However, there are no plans to remove them since it is difficult to migrate existing legacy systems.