Spring Security provides comprehensive security services for Java EE-based enterprise software applications. There is a particular emphasis on supporting projects built using The Spring Framework, which is the leading Java EE solution for enterprise software development. If you’re not using Spring for developing enterprise applications, we warmly encourage you to take a closer look at it. Some familiarity with Spring - and in particular dependency injection principles - will help you get up to speed with Spring Security more easily.

People use Spring Security for many reasons, but most are drawn to the project after finding the security features of Java EE’s Servlet Specification or EJB Specification lack the depth required for typical enterprise application scenarios. Whilst mentioning these standards, it’s important to recognise that they are not portable at a WAR or EAR level. Therefore, if you switch server environments, it is typically a lot of work to reconfigure your application’s security in the new target environment. Using Spring Security overcomes these problems, and also brings you dozens of other useful, customisable security features.

As you probably know two major areas of application security are "authentication" and "authorization" (or "access-control"). These are the two main areas that Spring Security targets. "Authentication" is the process of establishing a principal is who they claim to be (a "principal" generally means a user, device or some other system which can perform an action in your application)."Authorization" refers to the process of deciding whether a principal is allowed to perform an action within your application. To arrive at the point where an authorization decision is needed, the identity of the principal has already been established by the authentication process. These concepts are common, and not at all specific to Spring Security.

At an authentication level, Spring Security supports a wide range of authentication models. Most of these authentication models are either provided by third parties, or are developed by relevant standards bodies such as the Internet Engineering Task Force. In addition, Spring Security provides its own set of authentication features. Specifically, Spring Security currently supports authentication integration with all of these technologies:

(* Denotes provided by a third party

Many independent software vendors (ISVs) adopt Spring Security because of this significant choice of flexible authentication models. Doing so allows them to quickly integrate their solutions with whatever their end clients need, without undertaking a lot of engineering or requiring the client to change their environment. If none of the above authentication mechanisms suit your needs, Spring Security is an open platform and it is quite simple to write your own authentication mechanism. Many corporate users of Spring Security need to integrate with "legacy" systems that don’t follow any particular security standards, and Spring Security is happy to "play nicely" with such systems.

Irrespective of the authentication mechanism, Spring Security provides a deep set of authorization capabilities. There are three main areas of interest: authorizing web requests, authorizing whether methods can be invoked and authorizing access to individual domain object instances. To help you understand the differences, consider the authorization capabilities found in the Servlet Specification web pattern security, EJB Container Managed Security and file system security respectively. Spring Security provides deep capabilities in all of these important areas, which we’ll explore later in this reference guide.

Spring Security began in late 2003 as "The Acegi Security System for Spring". A question was posed on the Spring Developers' mailing list asking whether there had been any consideration given to a Spring-based security implementation. At the time the Spring community was relatively small (especially compared with the size today!), and indeed Spring itself had only existed as a SourceForge project from early 2003. The response to the question was that it was a worthwhile area, although a lack of time currently prevented its exploration.

With that in mind, a simple security implementation was built and not released. A few weeks later another member of the Spring community inquired about security, and at the time this code was offered to them. Several other requests followed, and by January 2004 around twenty people were using the code. These pioneering users were joined by others who suggested a SourceForge project was in order, which was duly established in March 2004.

In those early days, the project didn’t have any of its own authentication modules. Container Managed Security was relied upon for the authentication process, with Acegi Security instead focusing on authorization. This was suitable at first, but as more and more users requested additional container support, the fundamental limitation of container-specific authentication realm interfaces became clear. There was also a related issue of adding new JARs to the container’s classpath, which was a common source of end user confusion and misconfiguration.

Acegi Security-specific authentication services were subsequently introduced. Around a year later, Acegi Security became an official Spring Framework subproject. The 1.0.0 final release was published in May 2006 - after more than two and a half years of active use in numerous production software projects and many hundreds of improvements and community contributions.

Acegi Security became an official Spring Portfolio project towards the end of 2007 and was rebranded as "Spring Security".

Today Spring Security enjoys a strong and active open source community. There are thousands of messages about Spring Security on the support forums. There is an active core of developers who work on the code itself and an active community which also regularly share patches and support their peers.

It is useful to understand how Spring Security release numbers work, as it will help you identify the effort (or lack thereof) involved in migrating to future releases of the project. Each release uses a standard triplet of integers: MAJOR.MINOR.PATCH. The intent is that MAJOR versions are incompatible, large-scale upgrades of the API. MINOR versions should largely retain source and binary compatibility with older minor versions, thought there may be some design changes and incompatible updates. PATCH level should be perfectly compatible, forwards and backwards, with the possible exception of changes which are to fix bugs and defects.

The extent to which you are affected by changes will depend on how tightly integrated your code is. If you are doing a lot of customization you are more likely to be affected than if you are using a simple namespace configuration.

You should always test your application thoroughly before rolling out a new version.

You can get hold of Spring Security in several ways. You can download a packaged distribution from the main Spring Security page, download individual jars from the Maven Central repository (or a Spring Maven repository for snapshot and milestone releases) or, alternatively, you can build the project from source yourself.

2.4.1 Usage with Maven

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>4.2.6.RELEASE</version>
</dependency>
<dependency>
	<groupId>org.springframework.security</groupId>
	<artifactId>spring-security-config</artifactId>
	<version>4.2.6.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”.

Maven Repositories

All GA releases (i.e. versions ending in .RELEASE) are deployed to Maven Central, so no additional Maven repositories need to be declared in your pom.

If you are using a SNAPSHOT version, you will need to ensure you have the Spring Snapshot repository defined as shown below:

pom.xml. 

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

If you are using a milestone or release candidate version, you will need to ensure you have the Spring Milestone repository defined as shown below:

pom.xml. 

<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 4.3.17.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 4.3.17.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>4.3.17.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 4.3.17.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.

2.4.2 Gradle

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

build.gradle. 

dependencies {
	compile 'org.springframework.security:spring-security-web:4.2.6.RELEASE'
	compile 'org.springframework.security:spring-security-config:4.2.6.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”.

Gradle Repositories

All GA releases (i.e. versions ending in .RELEASE) are deployed to Maven Central, so using the mavenCentral() repository is sufficient for GA releases.

build.gradle. 

repositories {
	mavenCentral()
}

If you are using a SNAPSHOT version, you will need to ensure you have the Spring Snapshot repository defined as shown below:

build.gradle. 

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

If you are using a milestone or release candidate version, you will need to ensure you have the Spring Milestone repository defined as shown below:

build.gradle. 

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 4.2.6.RELEASE with Spring Framework 4.3.17.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 '4.3.17.RELEASE'
		}
	}
}

This will ensure that all the transitive dependencies of Spring Security use the Spring 4.3.17.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.

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

The first step is to create our Spring Security Java Configuration. The configuration creates a Servlet Filter known as the springSecurityFilterChain which is responsible for all the security (protecting the application URLs, validating submitted username and passwords, redirecting to the log in form, etc) within your application. You can find the most basic example of a Spring Security Java Configuration below:

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.context.annotation.*;
import org.springframework.security.config.annotation.authentication.builders.*;
import org.springframework.security.config.annotation.web.configuration.*;

@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {

	@Bean
	public UserDetailsService userDetailsService() throws Exception {
		InMemoryUserDetailsManager manager = new InMemoryUserDetailsManager();
		manager.createUser(User.withUsername("user").password("password").roles("USER").build());
		return manager;
	}
}

There really isn’t much to this configuration, but it does a lot. You can find a summary of the features below:

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

public class SecurityWebApplicationInitializer
	extends AbstractSecurityWebApplicationInitializer {

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

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

public class SecurityWebApplicationInitializer
	extends AbstractSecurityWebApplicationInitializer {

}

public class MvcWebApplicationInitializer extends
		AbstractAnnotationConfigDispatcherServletInitializer {

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

	// ... other overrides ...
}

Thus far our WebSecurityConfig only contains information about how to authenticate our users. How does Spring Security know that we want to require all users to be authenticated? How does Spring Security know we want to support form based authentication? The reason for this is that the WebSecurityConfigurerAdapter provides a default configuration in the configure(HttpSecurity http) method that looks like:

protected void configure(HttpSecurity http) throws Exception {
	http
		.authorizeRequests()
			.anyRequest().authenticated()
			.and()
		.formLogin()
			.and()
		.httpBasic();
}

The default configuration above:

You will notice that this configuration is quite similar the XML Namespace configuration:

<http>
	<intercept-url pattern="/**" access="authenticated"/>
	<form-login />
	<http-basic />
</http>

The Java Configuration equivalent of closing an XML tag is expressed using the and() method which allows us to continue configuring the parent. If you read the code it also makes sense. I want to configure authorized requests and configure form login and configure HTTP Basic authentication.

However, Java Configuration has different defaults URLs and parameters. Keep this in mind when creating custom login pages. The result is that our URLs are more RESTful. Additionally, it is not quite so obvious we are using Spring Security which helps to prevent information leaks. For example:

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. Since Spring Security’s default configuration does not 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.

While the automatically generated log in page is convenient to get up and running quickly, most applications will want to provide their own log in page. To do so we can update our configuration as seen below:

protected void configure(HttpSecurity http) throws Exception {
	http
		.authorizeRequests()
			.anyRequest().authenticated()
			.and()
		.formLogin()
			.loginPage("/login") 
			.permitAll();        
}

An example log in page implemented with JSPs for our current configuration can be seen below:

	Note
	The login page below represents our current configuration. We could easily update our configuration if some of the defaults do not meet our needs.

<c:url value="/login" var="loginUrl"/>
<form action="${loginUrl}" method="post">       
	<c:if test="${param.error != null}">        
		<p>
			Invalid username and password.
		</p>
	</c:if>
	<c:if test="${param.logout != null}">       
		<p>
			You have been logged out.
		</p>
	</c:if>
	<p>
		<label for="username">Username</label>
		<input type="text" id="username" name="username"/>	
	</p>
	<p>
		<label for="password">Password</label>
		<input type="password" id="password" name="password"/>	
	</p>
	<input type="hidden"                        
		name="${_csrf.parameterName}"
		value="${_csrf.token}"/>
	<button type="submit" class="btn">Log in</button>
</form>

Our examples have only required users to be authenticated and have done so for every URL in our application. We can specify custom requirements for our URLs by adding multiple children to our http.authorizeRequests() method. For example:

protected void configure(HttpSecurity http) throws Exception {
	http
		.authorizeRequests()                                                                
			.antMatchers("/resources/**", "/signup", "/about").permitAll()                  
			.antMatchers("/admin/**").hasRole("ADMIN")                                      
			.antMatchers("/db/**").access("hasRole('ADMIN') and hasRole('DBA')")            
			.anyRequest().authenticated()                                                   
			.and()
		// ...
		.formLogin();
}

When using the WebSecurityConfigurerAdapter, logout capabilities are automatically applied. The default is that accessing the URL /logout will log the user out by:

Similar to configuring login capabilities, however, you also have various options to further customize your logout requirements:

protected void configure(HttpSecurity http) throws Exception {
	http
		.logout()                                                                
			.logoutUrl("/my/logout")                                                 
			.logoutSuccessUrl("/my/index")                                           
			.logoutSuccessHandler(logoutSuccessHandler)                              
			.invalidateHttpSession(true)                                             
			.addLogoutHandler(logoutHandler)                                         
			.deleteCookies(cookieNamesToClear)                                       
			.and()
		...
}

	Note
	Logouts can of course also be configured using the XML Namespace notation. Please see the documentation for the logout element in the Spring Security XML Namespace section for further details.

Generally, in order to customize logout functionality, you can add LogoutHandler and/or LogoutSuccessHandler implementations. For many common scenarios, these handlers are applied under the covers when using the fluent API.

Thus far we have only taken a look at the most basic authentication configuration. Let’s take a look at a few slightly more advanced options for configuring authentication.

@Bean
public UserDetailsService userDetailsService() throws Exception {
	InMemoryUserDetailsManager manager = new InMemoryUserDetailsManager();
	manager.createUser(User.withUsername("user").password("password").roles("USER").build());
	manager.createUser(User.withUsername("admin").password("password").roles("USER","ADMIN").build());
	return manager;
}

@Autowired
private DataSource dataSource;

@Autowired
public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
	auth
		.jdbcAuthentication()
			.dataSource(dataSource)
			.withDefaultSchema()
			.withUser("user").password("password").roles("USER").and()
			.withUser("admin").password("password").roles("USER", "ADMIN");
}

@Autowired
private DataSource dataSource;

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

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

5.6.4 AuthenticationProvider

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();
}

5.6.5 UserDetailsService

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 configure multiple HttpSecurity instances just as we can have multiple <http> blocks. The key is to extend the WebSecurityConfigurerAdapter multiple times. For example, the following is an example of having a different configuration for URL’s that start with /api/.

@EnableWebSecurity
public class MultiHttpSecurityConfig {
	@Bean
	public UserDetailsService userDetailsService() throws Exception {
		InMemoryUserDetailsManager manager = new InMemoryUserDetailsManager();
		manager.createUser(User.withUsername("user").password("password").roles("USER").build());
		manager.createUser(User.withUsername("admin").password("password").roles("USER","ADMIN").build());
		return manager;
	}

	@Configuration
	@Order(1)                                                        
	public static class ApiWebSecurityConfigurationAdapter extends WebSecurityConfigurerAdapter {
		protected void configure(HttpSecurity http) throws Exception {
			http
				.antMatcher("/api/**")                               
				.authorizeRequests()
					.anyRequest().hasRole("ADMIN")
					.and()
				.httpBasic();
		}
	}

	@Configuration                                                   
	public static class FormLoginWebSecurityConfigurerAdapter extends WebSecurityConfigurerAdapter {

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

From version 2.0 onwards Spring Security has improved support substantially for adding security to your service layer methods. It provides support for JSR-250 annotation security as well as the framework’s original @Secured annotation. From 3.0 you can also make use of new expression-based annotations. You can apply security to a single bean, using the intercept-methods element to decorate the bean declaration, or you can secure multiple beans across the entire service layer using the AspectJ style pointcuts.

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

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);
}

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

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

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);
}

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

Spring Security’s Java Configuration does not expose every property of every object that it configures. This simplifies the configuration for a majority of users. Afterall, if every property was exposed, users could use standard bean configuration.

While there are good reasons to not directly expose every property, users may still need more advanced configuration options. To address this Spring Security introduces the concept of an ObjectPostProcessor which can be used to modify or replace many of the Object instances created by the Java Configuration. For example, if you wanted to configure the filterSecurityPublishAuthorizationSuccess property on FilterSecurityInterceptor you could use the following:

@Override
protected void configure(HttpSecurity http) throws Exception {
	http
		.authorizeRequests()
			.anyRequest().authenticated()
			.withObjectPostProcessor(new ObjectPostProcessor<FilterSecurityInterceptor>() {
				public <O extends FilterSecurityInterceptor> O postProcess(
						O fsi) {
					fsi.setPublishAuthorizationSuccess(true);
					return fsi;
				}
			});
}

You can provide your own custom DSLs in Spring Security. For example, you might have something that looks like this:

public class MyCustomDsl extends AbstractHttpConfigurer<CorsConfigurerMyCustomDsl, HttpSecurity> {
	private boolean flag;

	@Override
	public void init(H http) throws Exception {
		// any method that adds another configurer
		// must be done in the init method
		http.csrf().disable();
	}

	@Override
	public void configure(H http) throws Exception {
		ApplicationContext context = http.getSharedObject(ApplicationContext.class);

		// here we lookup from the ApplicationContext. You can also just create a new instance.
		MyFilter myFilter = context.getBean(MyFilter.class);
		myFilter.setFlag(flag);
		http.addFilterBefore(myFilter, UsernamePasswordAuthenticationFilter.class);
	}

	public MyCustomDsl flag(boolean value) {
		this.flag = value;
		return this;
	}

	public static MyCustomDsl customDsl() {
		return new MyCustomDsl();
	}
}

	Note
	This is actually how methods like HttpSecurity.authorizeRequests() are implemented.

The custom DSL can then be used like this:

@EnableWebSecurity
public class Config extends WebSecurityConfigurerAdapter {
	@Override
	protected void configure(HttpSecurity http) throws Exception {
		http
			.apply(customDsl())
				.flag(true)
				.and()
			...;
	}
}

The code is invoked in the following order:

If you want, you can have WebSecurityConfiguerAdapter add MyCustomDsl by default by using SpringFactories. For example, you would create a resource on the classpath named META-INF/spring.factories with the following contents:

META-INF/spring.factories. 

org.springframework.security.config.annotation.web.configurers.AbstractHttpConfigurer = sample.MyCustomDsl

Users wishing to disable the default can do so explicitly.

@EnableWebSecurity
public class Config extends WebSecurityConfigurerAdapter {
	@Override
	protected void configure(HttpSecurity http) throws Exception {
		http
			.apply(customDsl()).disable()
			...;
	}
}

Namespace configuration has been available since version 2.0 of the Spring Framework. It allows you to supplement the traditional Spring beans application context syntax with elements from additional XML schema. You can find more information in the Spring Reference Documentation. A namespace element can be used simply to allow a more concise way of configuring an individual bean or, more powerfully, to define an alternative configuration syntax which more closely matches the problem domain and hides the underlying complexity from the user. A simple element may conceal the fact that multiple beans and processing steps are being added to the application context. For example, adding the following element from the security namespace to an application context will start up an embedded LDAP server for testing use within the application:

<security:ldap-server />

This is much simpler than wiring up the equivalent Apache Directory Server beans. The most common alternative configuration requirements are supported by attributes on the ldap-server element and the user is isolated from worrying about which beans they need to create and what the bean property names are. ^[1]. Use of a good XML editor while editing the application context file should provide information on the attributes and elements that are available. We would recommend that you try out the Spring Tool Suite as it has special features for working with standard Spring namespaces.

To start using the security namespace in your application context, you need to have the spring-security-config jar on your classpath. Then all you need to do is add the schema declaration to your application context file:

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:security="http://www.springframework.org/schema/security"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
		http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
		http://www.springframework.org/schema/security
		http://www.springframework.org/schema/security/spring-security.xsd">
	...
</beans>

In many of the examples you will see (and in the sample applications), we will often use "security" as the default namespace rather than "beans", which means we can omit the prefix on all the security namespace elements, making the content easier to read. You may also want to do this if you have your application context divided up into separate files and have most of your security configuration in one of them. Your security application context file would then start like this

<beans:beans xmlns="http://www.springframework.org/schema/security"
xmlns:beans="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
		http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
		http://www.springframework.org/schema/security
		http://www.springframework.org/schema/security/spring-security.xsd">
	...
</beans:beans>

We’ll assume this syntax is being used from now on in this chapter.

In this section, we’ll look at how you can build up a namespace configuration to use some of the main features of the framework. Let’s assume you initially want to get up and running as quickly as possible and add authentication support and access control to an existing web application, with a few test logins. Then we’ll look at how to change over to authenticating against a database or other security repository. In later sections we’ll introduce more advanced namespace configuration options.

<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>

6.2.2 A Minimal <http> Configuration

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>
	<user name="jimi" password="jimispassword" authorities="ROLE_USER, ROLE_ADMIN" />
	<user name="bob" password="bobspassword" authorities="ROLE_USER" />
	</user-service>
</authentication-provider>
</authentication-manager>

If you are familiar with pre-namespace versions of the framework, you can probably already guess roughly what’s going on here. The <http> element is responsible for creating a FilterChainProxy and the filter beans which it uses. Common problems like incorrect filter ordering are no longer an issue as the filter positions are predefined.

The <authentication-provider> element creates a DaoAuthenticationProvider bean and the <user-service> element creates an InMemoryDaoImpl. All authentication-provider elements must be children of the <authentication-manager> element, which creates a ProviderManager and registers the authentication providers with it. You can find more detailed information on the beans that are created in the namespace appendix. It’s worth cross-checking this if you want to start understanding what the important classes in the framework are and how they are used, particularly if you want to customise things later.

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.

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

<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>

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

<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>

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

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

<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>

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

<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="d7e6351eaa13189a5a3641bab846c8e8c69ba39f"
			authorities="ROLE_USER, ROLE_ADMIN" />
	<user name="bob" password="4e7421b1b8765d8f9406d87e7cc6aa784c4ab97f"
			authorities="ROLE_USER" />
	</user-service>
</authentication-provider>
</authentication-manager>

From version 2.0 onwards Spring Security has improved support substantially for adding security to your service layer methods. It provides support for JSR-250 annotation security as well as the framework’s original @Secured annotation. From 3.0 you can also make use of new expression-based annotations. You can apply security to a single bean, using the intercept-methods element to decorate the bean declaration, or you can secure multiple beans across the entire service layer using the AspectJ style pointcuts.

6.4.1 The <global-method-security> Element

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.

Adding Security Pointcuts using protect-pointcut

The use of protect-pointcut is particularly powerful, as it allows you to apply security to many beans with only a simple declaration. Consider the following example:

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

This will protect all methods on beans declared in the application context whose classes are in the com.mycompany package and whose class names end in "Service". Only users with the ROLE_USER role will be able to invoke these methods. As with URL matching, the most specific matches must come first in the list of pointcuts, as the first matching expression will be used. Security annotations take precedence over pointcuts.

This section assumes you have some knowledge of the underlying architecture for access-control within Spring Security. If you don’t you can skip it and come back to it later, as this section is only really relevant for people who need to do some customization in order to use more than simple role-based security.

When you use a namespace configuration, a default instance of AccessDecisionManager is automatically registered for you and will be used for making access decisions for method invocations and web URL access, based on the access attributes you specify in your intercept-url and protect-pointcut declarations (and in annotations if you are using annotation secured methods).

The default strategy is to use an AffirmativeBased AccessDecisionManager with a RoleVoter and an AuthenticatedVoter. You can find out more about these in the chapter on authorization.

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

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

The main interface which provides authentication services in Spring Security is the AuthenticationManager. This is usually an instance of Spring Security’s ProviderManager class, which you may already be familiar with if you’ve used the framework before. If not, it will be covered later, in the technical overview chapter. The bean instance is registered using the authentication-manager namespace element. You can’t use a custom AuthenticationManager if you are using either HTTP or method security through the namespace, but this should not be a problem as you have full control over the AuthenticationProvider s that are used.

You may want to register additional AuthenticationProvider beans with the ProviderManager and you can do this using the <authentication-provider> element with the ref attribute, where the value of the attribute is the name of the provider bean you want to add. For example:

<authentication-manager>
<authentication-provider ref="casAuthenticationProvider"/>
</authentication-manager>

<bean id="casAuthenticationProvider"
	class="org.springframework.security.cas.authentication.CasAuthenticationProvider">
...
</bean>

Another common requirement is that another bean in the context may require a reference to the AuthenticationManager. You can easily register an alias for the AuthenticationManager and use this name elsewhere in your application context.

<security:authentication-manager alias="authenticationManager">
...
</security:authentication-manager>

<bean id="customizedFormLoginFilter"
	class="com.somecompany.security.web.CustomFormLoginFilter">
<property name="authenticationManager" ref="authenticationManager"/>
...
</bean>

The tutorial sample is a nice basic example to get you started. It uses simple namespace configuration throughout. The compiled application is included in the distribution zip file, ready to be deployed into your web container (spring-security-samples-tutorial-3.1.x.war). The form-based authentication mechanism is used in combination with the commonly-used remember-me authentication provider to automatically remember the login using cookies.

We recommend you start with the tutorial sample, as the XML is minimal and easy to follow. Most importantly, you can easily add this one XML file (and its corresponding web.xml entries) to your existing application. Only when this basic integration is achieved do we suggest you attempt adding in method authorization or domain object security.

The Contacts Sample is an advanced example in that it illustrates the more powerful features of domain object access control lists (ACLs) in addition to basic application security. The application provides an interface with which the users are able to administer a simple database of contacts (the domain objects).

To deploy, simply copy the WAR file from Spring Security distribution into your container’s webapps directory. The war should be called spring-security-samples-contacts-3.1.x.war (the appended version number will vary depending on what release you are using).

After starting your container, check the application can load. Visit http://localhost:8080/contacts (or whichever URL is appropriate for your web container and the WAR you deployed).

Next, click "Debug". You will be prompted to authenticate, and a series of usernames and passwords are suggested on that page. Simply authenticate with any of these and view the resulting page. It should contain a success message similar to the following:

Security Debug Information

Authentication object is of type:
org.springframework.security.authentication.UsernamePasswordAuthenticationToken

Authentication object as a String:

org.springframework.security.authentication.UsernamePasswordAuthenticationToken@1f127853:
Principal: org.springframework.security.core.userdetails.User@b07ed00: Username: rod; \
Password: [PROTECTED]; Enabled: true; AccountNonExpired: true;
credentialsNonExpired: true; AccountNonLocked: true; \
Granted Authorities: ROLE_SUPERVISOR, ROLE_USER; \
Password: [PROTECTED]; Authenticated: true; \
Details: org.springframework.security.web.authentication.WebAuthenticationDetails@0: \
RemoteIpAddress: 127.0.0.1; SessionId: 8fkp8t83ohar; \
Granted Authorities: ROLE_SUPERVISOR, ROLE_USER

Authentication object holds the following granted authorities:

ROLE_SUPERVISOR (getAuthority(): ROLE_SUPERVISOR)
ROLE_USER (getAuthority(): ROLE_USER)

Success! Your web filters appear to be properly configured!

Once you successfully receive the above message, return to the sample application’s home page and click "Manage". You can then try out the application. Notice that only the contacts available to the currently logged on user are displayed, and only users with ROLE_SUPERVISOR are granted access to delete their contacts. Behind the scenes, the MethodSecurityInterceptor is securing the business objects.

The application allows you to modify the access control lists associated with different contacts. Be sure to give this a try and understand how it works by reviewing the application context XML files.

The LDAP sample application provides a basic configuration and sets up both a namespace configuration and an equivalent configuration using traditional beans, both in the same application context file. This means there are actually two identical authentication providers configured in this application.

The OpenID sample demonstrates how to use the namespace to configure OpenID and how to set up attribute exchange configurations for Google, Yahoo and MyOpenID identity providers (you can experiment with adding others if you wish). It uses the JQuery-based openid-selector project to provide a user-friendly login page which allows the user to easily select a provider, rather than typing in the full OpenID identifier.

The application differs from normal authentication scenarios in that it allows any user to access the site (provided their OpenID authentication is successful). The first time you login, you will get a "Welcome [your name]"" message. If you logout and log back in (with the same OpenID identity) then this should change to "Welcome Back". This is achieved by using a custom UserDetailsService which assigns a standard role to any user and stores the identities internally in a map. Obviously a real application would use a database instead. Have a look at the source form more information. This class also takes into account the fact that different attributes may be returned from different providers and builds the name with which it addresses the user accordingly.

The CAS sample requires that you run both a CAS server and CAS client. It isn’t included in the distribution so you should check out the project code as described in the introduction. You’ll find the relevant files under the sample/cas directory. There’s also a Readme.txt file in there which explains how to run both the server and the client directly from the source tree, complete with SSL support.

The JAAS sample is very simple example of how to use a JAAS LoginModule with Spring Security. The provided LoginModule will successfully authenticate a user if the username equals the password otherwise a LoginException is thrown. The AuthorityGranter used in this example always grants the role ROLE_USER. The sample application also demonstrates how to run as the JAAS Subject returned by the LoginModule by setting jaas-api-provision equal to "true".

This sample application demonstrates how to wire up beans from the pre-authentication framework to make use of login information from a Java EE container. The user name and roles are those setup by the container.

The code is in samples/preauth.

Spring Security uses JIRA to manage bug reports and enhancement requests. If you find a bug, please log a report using JIRA. Do not log it on the support forum, mailing list or by emailing the project’s developers. Such approaches are ad-hoc and we prefer to manage bugs using a more formal process.

If possible, in your issue report please provide a JUnit test that demonstrates any incorrect behaviour. Or, better yet, provide a patch that corrects the issue. Similarly, enhancements are welcome to be logged in the issue tracker, although we only accept enhancement requests if you include corresponding unit tests. This is necessary to ensure project test coverage is adequately maintained.

You can access the issue tracker at https://github.com/spring-projects/spring-security/issues.

We welcome your involvement in the Spring Security project. There are many ways of contributing, including reading the forum and responding to questions from other people, writing new code, improving existing code, assisting with documentation, developing samples or tutorials, or simply making suggestions.

Questions and comments on Spring Security are welcome. You can use the Spring at Stack Overflow web site at http://spring.io/questions to discuss Spring Security with other users of the framework. Remember to use JIRA for bug reports, as explained above.

Spring Security 3.0 requires a Java 5.0 Runtime Environment or higher. As Spring Security aims to operate in a self-contained manner, there is no need to place any special configuration files into your Java Runtime Environment. In particular, there is no need to configure a special Java Authentication and Authorization Service (JAAS) policy file or place Spring Security into common classpath locations.

Similarly, if you are using an EJB Container or Servlet Container there is no need to put any special configuration files anywhere, nor include Spring Security in a server classloader. All the required files will be contained within your application.

This design offers maximum deployment time flexibility, as you can simply copy your target artifact (be it a JAR, WAR or EAR) from one system to another and it will immediately work.

In Spring Security 3.0, the contents of the spring-security-core jar were stripped down to the bare minimum. It no longer contains any code related to web-application security, LDAP or namespace configuration. We’ll take a look here at some of the Java types that you’ll find in the core module. They represent the building blocks of the framework, so if you ever need to go beyond a simple namespace configuration then it’s important that you understand what they are, even if you don’t actually need to interact with them directly.

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

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

9.2.2 The UserDetailsService

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.

Spring Security can participate in many different authentication environments. While we recommend people use Spring Security for authentication and not integrate with existing Container Managed Authentication, it is nevertheless supported - as is integrating with your own proprietary authentication system.

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");
}
}

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

<b:bean id="httpFirewall"
      class="org.springframework.security.web.firewall.StrictHttpFirewall"
      p:allowSemicolon="true"/>

<http-firewall ref="httpFirewall"/>

@Bean
public StrictHttpFirewall httpFirewall() {
    StrictHttpFirewall firewall = new StrictHttpFirewall();
    firewall.setAllowSemicolon(true);
    return firewall;
}

Now let’s explore the situation where you are using Spring Security in a web application (without web.xml security enabled). How is a user authenticated and the security context established?

Consider a typical web application’s authentication process:

Spring Security has distinct classes responsible for most of the steps described above. The main participants (in the order that they are used) are the ExceptionTranslationFilter, an AuthenticationEntryPoint and an "authentication mechanism", which is responsible for calling the AuthenticationManager which we saw in the previous section.

9.4.4 Storing the SecurityContext between requests

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.

The main interface responsible for making access-control decisions in Spring Security is the AccessDecisionManager. It has a decide method which takes an Authentication object representing the principal requesting access, a "secure object" (see below) and a list of security metadata attributes which apply for the object (such as a list of roles which are required for access to be granted).

9.5.2 Secure Objects and the AbstractSecurityInterceptor

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:

1. Look up the "configuration attributes" associated with the present request
2. Submitting the secure object, current Authentication and configuration attributes to the AccessDecisionManager for an authorization decision
3. Optionally change the Authentication under which the invocation takes place
4. Allow the secure object invocation to proceed (assuming access was granted)
5. Call the AfterInvocationManager if configured, once the invocation has returned. If the invocation raised an exception, the AfterInvocationManager will not be invoked.

What are Configuration Attributes?

A "configuration attribute" can be thought of as a String that has special meaning to the classes used by AbstractSecurityInterceptor. They are represented by the interface ConfigAttribute within the framework. They may be simple role names or have more complex meaning, depending on the how sophisticated the AccessDecisionManager implementation is. The AbstractSecurityInterceptor is configured with a SecurityMetadataSource which it uses to look up the attributes for a secure object. Usually this configuration will be hidden from the user. Configuration attributes will be entered as annotations on secured methods or as access attributes on secured URLs. For example, when we saw something like <intercept-url pattern='/secure/**' access='ROLE_A,ROLE_B'/> in the namespace introduction, this is saying that the configuration attributes ROLE_A and ROLE_B apply to web requests matching the given pattern. In practice, with the default AccessDecisionManager configuration, this means that anyone who has a GrantedAuthority matching either of these two attributes will be allowed access. Strictly speaking though, they are just attributes and the interpretation is dependent on the AccessDecisionManager implementation. The use of the prefix ROLE_ is a marker to indicate that these attributes are roles and should be consumed by Spring Security’s RoleVoter. This is only relevant when a voter-based AccessDecisionManager is in use. We’ll see how the AccessDecisionManager is implemented in the authorization chapter.

RunAsManager

Assuming AccessDecisionManager decides to allow the request, the AbstractSecurityInterceptor will normally just proceed with the request. Having said that, on rare occasions users may want to replace the Authentication inside the SecurityContext with a different Authentication, which is handled by the AccessDecisionManager calling a RunAsManager. This might be useful in reasonably unusual situations, such as if a services layer method needs to call a remote system and present a different identity. Because Spring Security automatically propagates security identity from one server to another (assuming you’re using a properly-configured RMI or HttpInvoker remoting protocol client), this may be useful.

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

Extending the Secure Object Model

Only developers contemplating an entirely new way of intercepting and authorizing requests would need to use secure objects directly. For example, it would be possible to build a new secure object to secure calls to a messaging system. Anything that requires security and also provides a way of intercepting a call (like the AOP around advice semantics) is capable of being made into a secure object. Having said that, most Spring applications will simply use the three currently supported secure object types (AOP Alliance MethodInvocation, AspectJ JoinPoint and web request FilterInvocation) with complete transparency.

Spring Security supports localization of exception messages that end users are likely to see. If your application is designed for English-speaking users, you don’t need to do anything as by default all Security messages are in English. If you need to support other locales, everything you need to know is contained in this section.

All exception messages can be localized, including messages related to authentication failures and access being denied (authorization failures). Exceptions and logging messages that are focused on developers or system deployers (including incorrect attributes, interface contract violations, using incorrect constructors, startup time validation, debug-level logging) are not localized and instead are hard-coded in English within Spring Security’s code.

Shipping in the spring-security-core-xx.jar you will find an org.springframework.security package that in turn contains a messages.properties file, as well as localized versions for some common languages. This should be referred to by your ApplicationContext, as Spring Security classes implement Spring’s MessageSourceAware interface and expect the message resolver to be dependency injected at application context startup time. Usually all you need to do is register a bean inside your application context to refer to the messages. An example is shown below:

<bean id="messageSource"
	class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
<property name="basename" value="classpath:org/springframework/security/messages"/>
</bean>

The messages.properties is named in accordance with standard resource bundles and represents the default language supported by Spring Security messages. This default file is in English.

If you wish to customize the messages.properties file, or support other languages, you should copy the file, rename it accordingly, and register it inside the above bean definition. There are not a large number of message keys inside this file, so localization should not be considered a major initiative. If you do perform localization of this file, please consider sharing your work with the community by logging a JIRA task and attaching your appropriately-named localized version of messages.properties.

Spring Security relies on Spring’s localization support in order to actually lookup the appropriate message. In order for this to work, you have to make sure that the locale from the incoming request is stored in Spring’s org.springframework.context.i18n.LocaleContextHolder. Spring MVC’s DispatcherServlet does this for your application automatically, but since Spring Security’s filters are invoked before this, the LocaleContextHolder needs to be set up to contain the correct Locale before the filters are called. You can either do this in a filter yourself (which must come before the Spring Security filters in web.xml) or you can use Spring’s RequestContextFilter. Please refer to the Spring Framework documentation for further details on using localization with Spring.

The "contacts" sample application is set up to use localized messages.

The AuthenticationManager is just an interface, so the implementation can be anything we choose, but how does it work in practice? What if we need to check multiple authentication databases or a combination of different authentication services such as a database and an LDAP server?

The default implementation in Spring Security is called ProviderManager and rather than handling the authentication request itself, it delegates to a list of configured AuthenticationProvider s, each of which is queried in turn to see if it can perform the authentication. Each provider will either throw an exception or return a fully populated Authentication object. Remember our good friends, UserDetails and UserDetailsService? If not, head back to the previous chapter and refresh your memory. The most common approach to verifying an authentication request is to load the corresponding UserDetails and check the loaded password against the one that has been entered by the user. This is the approach used by the DaoAuthenticationProvider (see below). The loaded UserDetails object - and particularly the GrantedAuthority s it contains - will be used when building the fully populated Authentication object which is returned from a successful authentication and stored in the SecurityContext.

If you are using the namespace, an instance of ProviderManager is created and maintained internally, and you add providers to it by using the namespace authentication provider elements (see the namespace chapter). In this case, you should not declare a ProviderManager bean in your application context. However, if you are not using the namespace then you would declare it like so:

<bean id="authenticationManager"
		class="org.springframework.security.authentication.ProviderManager">
	<constructor-arg>
		<list>
			<ref local="daoAuthenticationProvider"/>
			<ref local="anonymousAuthenticationProvider"/>
			<ref local="ldapAuthenticationProvider"/>
		</list>
	</constructor-arg>
</bean>

In the above example we have three providers. They are tried in the order shown (which is implied by the use of a List), with each provider able to attempt authentication, or skip authentication by simply returning null. If all implementations return null, the ProviderManager will throw a ProviderNotFoundException. If you’re interested in learning more about chaining providers, please refer to the ProviderManager Javadoc.

Authentication mechanisms such as a web form-login processing filter are injected with a reference to the ProviderManager and will call it to handle their authentication requests. The providers you require will sometimes be interchangeable with the authentication mechanisms, while at other times they will depend on a specific authentication mechanism. For example, DaoAuthenticationProvider and LdapAuthenticationProvider are compatible with any mechanism which submits a simple username/password authentication request and so will work with form-based logins or HTTP Basic authentication. On the other hand, some authentication mechanisms create an authentication request object which can only be interpreted by a single type of AuthenticationProvider. An example of this would be JA-SIG CAS, which uses the notion of a service ticket and so can therefore only be authenticated by a CasAuthenticationProvider. You needn’t be too concerned about this, because if you forget to register a suitable provider, you’ll simply receive a ProviderNotFoundException when an attempt to authenticate is made.

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

As mentioned in the earlier in this reference guide, most authentication providers take advantage of the UserDetails and UserDetailsService interfaces. Recall that the contract for UserDetailsService is a single method:

UserDetails loadUserByUsername(String username) throws UsernameNotFoundException;

The returned UserDetails is an interface that provides getters that guarantee non-null provision of authentication information such as the username, password, granted authorities and whether the user account is enabled or disabled. Most authentication providers will use a UserDetailsService, even if the username and password are not actually used as part of the authentication decision. They may use the returned UserDetails object just for its GrantedAuthority information, because some other system (like LDAP or X.509 or CAS etc) has undertaken the responsibility of actually validating the credentials.

Given UserDetailsService is so simple to implement, it should be easy for users to retrieve authentication information using a persistence strategy of their choice. Having said that, Spring Security does include a couple of useful base implementations, which we’ll look at below.

<user-service id="userDetailsService">
<user name="jimi" password="jimispassword" authorities="ROLE_USER, ROLE_ADMIN" />
<user name="bob" password="bobspassword" authorities="ROLE_USER" />
</user-service>

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

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

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

<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>

Spring Security’s PasswordEncoder interface is used to support the use of passwords which are encoded in some way in persistent storage. You should never store passwords in plain text. Always use a one-way password hashing algorithm such as bcrypt which uses a built-in salt value which is different for each stored password. Do not use a plain hash function such as MD5 or SHA, or even a salted version. Bcrypt is deliberately designed to be slow and to hinder offline password cracking, whereas standard hash algorithms are fast and can easily be used to test thousands of passwords in parallel on custom hardware. You might think this doesn’t apply to you since your password database is secure and offline attacks aren’t a risk. If so, do some research and read up on all the high-profile sites which have been compromised in this way and have been pilloried for storing their passwords insecurely. It’s best to be on the safe side. Using org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder" is a good choice for security. There are also compatible implementations in other common programming languages so it a good choice for interoperability too.

If you are using a legacy system which already has hashed passwords, then you will need to use an encoder which matches your current algorithm, at least until you can migrate your users to a more secure scheme (usually this will involve asking the user to set a new password, since hashes are irreversible). Spring Security has a package containing legacy password encoding implementation, namely, org.springframework.security.authentication.encoding. The DaoAuthenticationProvider can be injected with either the new or legacy PasswordEncoder types.

5f4dcc3b5aa765d61d8327deb882cf99

10.3.2 Adding Salt to a Hash

One potential problem with the use of password hashes that it is relatively easy to get round the one-way property of the hash if a common word is used for the input. People tend to choose similar passwords and huge dictionaries of these from previously hacked sites are available online. For example, if you search for the hash value 5f4dcc3b5aa765d61d8327deb882cf99 using google, you will quickly find the original word "password". In a similar way, an attacker can build a dictionary of hashes from a standard word list and use this to lookup the original password. One way to help prevent this is to have a suitably strong password policy to try to prevent common words from being used. Another is to use a "salt" when calculating the hashes. This is an additional string of known data for each user which is combined with the password before calculating the hash. Ideally the data should be as random as possible, but in practice any salt value is usually preferable to none. Using a salt means that an attacker has to build a separate dictionary of hashes for each salt value, making the attack more complicated (but not impossible).

Bcrypt automatically generates a random salt value for each password when it is encoded, and stores it in the bcrypt string in a standard format.

Note

The legacy approach to handling salt was to inject a SaltSource into the DaoAuthenticationProvider, which would obtain a salt value for a particular user and pass it to the PasswordEncoder. Using bcrypt means you don’t have worry about the details of salt handling (such as where the value is stored), as it is all done internally. So we’d strongly recommend you use bcrypt unless you already have a system in place which stores the salt separately.

Spring Security has added Jackson Support for persisting Spring Security related classes. This can improve the performance of serializing Spring Security related classes when working with distributed sessions (i.e. session replication, Spring Session, etc).

To use it, register the JacksonJacksonModules.getModules(ClassLoader) as Jackson Modules.

ObjectMapper mapper = new ObjectMapper();
ClassLoader loader = getClass().getClassLoader();
List<Module> modules = SecurityJackson2Modules.getModules(loader);
mapper.registerModules(modules);

// ... use ObjectMapper as normally ...
SecurityContext context = new SecurityContextImpl();
// ...
String json = mapper.writeValueAsString(context);

Before we can use Spring Security Test support, we must perform some setup. An example can be seen below:

@RunWith(SpringJUnit4ClassRunner.class) 
@ContextConfiguration 
public class WithMockUserTests {

This is a basic example of how to setup Spring Security Test. The highlights are:

Note

Spring Security hooks into Spring Test support using the WithSecurityContextTestExecutionListener which will ensure our tests are ran with the correct user. It does this by populating the SecurityContextHolder prior to running our tests. After the test is done, it will clear out the SecurityContextHolder. If you only need Spring Security related support, you can replace @ContextConfiguration with @SecurityTestExecutionListeners.

Remember we added the @PreAuthorize annotation to our HelloMessageService and so it requires an authenticated user to invoke it. If we ran the following test, we would expect the following test will pass:

@Test(expected = AuthenticationCredentialsNotFoundException.class)
public void getMessageUnauthenticated() {
	messageService.getMessage();
}

The question is "How could we most easily run the test as a specific user?" The answer is to use @WithMockUser. The following test will be run as a user with the username "user", the password "password", and the roles "ROLE_USER".

@Test
@WithMockUser
public void getMessageWithMockUser() {
String message = messageService.getMessage();
...
}

Specifically the following is true:

Our example is nice because we are able to leverage a lot of defaults. What if we wanted to run the test with a different username? The following test would run with the username "customUser". Again, the user does not need to actually exist.

@Test
@WithMockUser("customUsername")
public void getMessageWithMockUserCustomUsername() {
	String message = messageService.getMessage();
...
}

We can also easily customize the roles. For example, this test will be invoked with the username "admin" and the roles "ROLE_USER" and "ROLE_ADMIN".

@Test
@WithMockUser(username="admin",roles={"USER","ADMIN"})
public void getMessageWithMockUserCustomUser() {
	String message = messageService.getMessage();
	...
}

If we do not want the value to automatically be prefixed with ROLE_ we can leverage the authorities attribute. For example, this test will be invoked with the username "admin" and the authorities "USER" and "ADMIN".

@Test
@WithMockUser(username = "admin", authorities = { "ADMIN", "USER" })
public void getMessageWithMockUserCustomAuthorities() {
	String message = messageService.getMessage();
	...
}

Of course it can be a bit tedious placing the annotation on every test method. Instead, we can place the annotation at the class level and every test will use the specified user. For example, the following would run every test with a user with the username "admin", the password "password", and the roles "ROLE_USER" and "ROLE_ADMIN".

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration
@WithMockUser(username="admin",roles={"USER","ADMIN"})
public class WithMockUserTests {

Using @WithAnonymousUser allows running as an anonymous user. This is especially convenient when you wish to run most of your tests with a specific user, but want to run a few tests as an anonymous user. For example, the following will run withMockUser1 and withMockUser2 using @WithMockUser and anonymous as an anonymous user.

@RunWith(SpringJUnit4ClassRunner.class)
@WithMockUser
public class WithUserClassLevelAuthenticationTests {

	@Test
	public void withMockUser1() {
	}

	@Test
	public void withMockUser2() {
	}

	@Test
	@WithAnonymousUser
	public void anonymous() throws Exception {
		// override default to run as anonymous user
	}
}

While @WithMockUser is a very convenient way to get started, it may not work in all instances. For example, it is common for applications to expect that the Authentication principal be of a specific type. This is done so that the application can refer to the principal as the custom type and reduce coupling on Spring Security.

The custom principal is often times returned by a custom UserDetailsService that returns an object that implements both UserDetails and the custom type. For situations like this, it is useful to create the test user using the custom UserDetailsService. That is exactly what @WithUserDetails does.

Assuming we have a UserDetailsService exposed as a bean, the following test will be invoked with an Authentication of type UsernamePasswordAuthenticationToken and a principal that is returned from the UserDetailsService with the username of "user".

@Test
@WithUserDetails
public void getMessageWithUserDetails() {
	String message = messageService.getMessage();
	...
}

We can also customize the username used to lookup the user from our UserDetailsService. For example, this test would be executed with a principal that is returned from the UserDetailsService with the username of "customUsername".

@Test
@WithUserDetails("customUsername")
public void getMessageWithUserDetailsCustomUsername() {
	String message = messageService.getMessage();
	...
}

We can also provide an explicit bean name to look up the UserDetailsService. For example, this test would look up the username of "customUsername" using the UserDetailsService with the bean name "myUserDetailsService".

@Test
@WithUserDetails(value="customUsername", userDetailsServiceBeanName="myUserDetailsService")
public void getMessageWithUserDetailsServiceBeanName() {
	String message = messageService.getMessage();
	...
}

Like @WithMockUser we can also place our annotation at the class level so that every test uses the same user. However unlike @WithMockUser, @WithUserDetails requires the user to exist.

We have seen that @WithMockUser is an excellent choice if we are not using a custom Authentication principal. Next we discovered that @WithUserDetails would allow us to use a custom UserDetailsService to create our Authentication principal but required the user to exist. We will now see an option that allows the most flexibility.

We can create our own annotation that uses the @WithSecurityContext to create any SecurityContext we want. For example, we might create an annotation named @WithMockCustomUser as shown below:

@Retention(RetentionPolicy.RUNTIME)
@WithSecurityContext(factory = WithMockCustomUserSecurityContextFactory.class)
public @interface WithMockCustomUser {

	String username() default "rob";

	String name() default "Rob Winch";
}

You can see that @WithMockCustomUser is annotated with the @WithSecurityContext annotation. This is what signals to Spring Security Test support that we intend to create a SecurityContext for the test. The @WithSecurityContext annotation requires we specify a SecurityContextFactory that will create a new SecurityContext given our @WithMockCustomUser annotation. You can find our WithMockCustomUserSecurityContextFactory implementation below:

public class WithMockCustomUserSecurityContextFactory
	implements WithSecurityContextFactory<WithMockCustomUser> {
	@Override
	public SecurityContext createSecurityContext(WithMockCustomUser customUser) {
		SecurityContext context = SecurityContextHolder.createEmptyContext();

		CustomUserDetails principal =
			new CustomUserDetails(customUser.name(), customUser.username());
		Authentication auth =
			new UsernamePasswordAuthenticationToken(principal, "password", principal.getAuthorities());
		context.setAuthentication(auth);
		return context;
	}
}

We can now annotate a test class or a test method with our new annotation and Spring Security’s WithSecurityContextTestExecutionListener will ensure that our SecurityContext is populated appropriately.

When creating your own WithSecurityContextFactory implementations, it is nice to know that they can be annotated with standard Spring annotations. For example, the WithUserDetailsSecurityContextFactory uses the @Autowired annotation to acquire the UserDetailsService:

final class WithUserDetailsSecurityContextFactory
	implements WithSecurityContextFactory<WithUserDetails> {

	private UserDetailsService userDetailsService;

	@Autowired
	public WithUserDetailsSecurityContextFactory(UserDetailsService userDetailsService) {
		this.userDetailsService = userDetailsService;
	}

	public SecurityContext createSecurityContext(WithUserDetails withUser) {
		String username = withUser.value();
		Assert.hasLength(username, "value() must be non-empty String");
		UserDetails principal = userDetailsService.loadUserByUsername(username);
		Authentication authentication = new UsernamePasswordAuthenticationToken(principal, principal.getPassword(), principal.getAuthorities());
		SecurityContext context = SecurityContextHolder.createEmptyContext();
		context.setAuthentication(authentication);
		return context;
	}
}

If you reuse the same user within your tests often, it is not ideal to have to repeatedly specify the attributes. For example, if there are many tests related to an administrative user with the username "admin" and the roles ROLE_USER and ROLE_ADMIN you would have to write:

@WithMockUser(username="admin",roles={"USER","ADMIN"})

Rather than repeating this everywhere, we can use a meta annotation. For example, we could create a meta annotation named WithMockAdmin:

@Retention(RetentionPolicy.RUNTIME)
@WithMockUser(value="rob",roles="ADMIN")
public @interface WithMockAdmin { }

Now we can use @WithMockAdmin in the same way as the more verbose @WithMockUser.

Meta annotations work with any of the testing annotations described above. For example, this means we could create a meta annotation for @WithUserDetails("admin") as well.

In order to use Spring Security with Spring MVC Test it is necessary to add the Spring Security FilterChainProxy as a Filter. It is also necessary to add Spring Security’s TestSecurityContextHolderPostProcessor to support Running as a User in Spring MVC Test with Annotations. This can be done using Spring Security’s SecurityMockMvcConfigurers.springSecurity(). For example:

	Note
	Spring Security’s testing support requires spring-test-4.1.3.RELEASE or greater.

import static org.springframework.security.test.web.servlet.setup.SecurityMockMvcConfigurers.*;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration
@WebAppConfiguration
public class CsrfShowcaseTests {

	@Autowired
	private WebApplicationContext context;

	private MockMvc mvc;

	@Before
	public void setup() {
		mvc = MockMvcBuilders
				.webAppContextSetup(context)
				.apply(springSecurity()) 
				.build();
	}

...

Spring MVC Test provides a convenient interface called a RequestPostProcessor that can be used to modify a request. Spring Security provides a number of RequestPostProcessor implementations that make testing easier. In order to use Spring Security’s RequestPostProcessor implementations ensure the following static import is used:

import static org.springframework.security.test.web.servlet.request.SecurityMockMvcRequestPostProcessors.*;

mvc
	.perform(post("/").with(csrf()))

mvc
	.perform(post("/").with(csrf().asHeader()))

mvc
	.perform(post("/").with(csrf().useInvalidToken()))

12.2.3 Running as a User in Spring MVC Test with RequestPostProcessor

There are a number of options available to associate a user to the current HttpServletRequest. For example, the following will run as a user (which does not need to exist) with the username "user", the password "password", and the role "ROLE_USER":

Note

The support works by associating the user to the HttpServletRequest. To associate the request to the SecurityContextHolder you need to ensure that the SecurityContextPersistenceFilter is associated with the MockMvc instance. A few ways to do this are: Invoking apply(springSecurity()) Adding Spring Security’s FilterChainProxy to MockMvc Manually adding SecurityContextPersistenceFilter to the MockMvc instance may make sense when using MockMvcBuilders.standaloneSetup

mvc
	.perform(get("/").with(user("user")))

You can easily make customizations. For example, the following will run as a user (which does not need to exist) with the username "admin", the password "pass", and the roles "ROLE_USER" and "ROLE_ADMIN".

mvc
	.perform(get("/admin").with(user("admin").password("pass").roles("USER","ADMIN")))

If you have a custom UserDetails that you would like to use, you can easily specify that as well. For example, the following will use the specified UserDetails (which does not need to exist) to run with a UsernamePasswordAuthenticationToken that has a principal of the specified UserDetails:

mvc
	.perform(get("/").with(user(userDetails)))

You can run as anonymous user using the following:

mvc
	.perform(get("/").with(anonymous()))

This is especially useful if you are running with a default user and wish to execute a few requests as an anonymous user.

If you want a custom Authentication (which does not need to exist) you can do so using the following:

mvc
	.perform(get("/").with(authentication(authentication)))

You can even customize the SecurityContext using the following:

mvc
	.perform(get("/").with(securityContext(securityContext)))

We can also ensure to run as a specific user for every request by using MockMvcBuilders's default request. For example, the following will run as a user (which does not need to exist) with the username "admin", the password "password", and the role "ROLE_ADMIN":

mvc = MockMvcBuilders
		.webAppContextSetup(context)
		.defaultRequest(get("/").with(user("user").roles("ADMIN")))
		.apply(springSecurity())
		.build();

If you find you are using the same user in many of your tests, it is recommended to move the user to a method. For example, you can specify the following in your own class named CustomSecurityMockMvcRequestPostProcessors:

public static RequestPostProcessor rob() {
	return user("rob").roles("ADMIN");
}

Now you can perform a static import on SecurityMockMvcRequestPostProcessors and use that within your tests:

import static sample.CustomSecurityMockMvcRequestPostProcessors.*;

...

mvc
	.perform(get("/").with(rob()))

Running as a User in Spring MVC Test with Annotations

As an alternative to using a RequestPostProcessor to create your user, you can use annotations described in Chapter 11, Testing Method Security. For example, the following will run the test with the user with username "user", password "password", and role "ROLE_USER":

@Test
@WithMockUser
public void requestProtectedUrlWithUser() throws Exception {
mvc
		.perform(get("/"))
		...
}

Alternatively, the following will run the test with the user with username "user", password "password", and role "ROLE_ADMIN":

@Test
@WithMockUser(roles="ADMIN")
public void requestProtectedUrlWithUser() throws Exception {
mvc
		.perform(get("/"))
		...
}

mvc
	.perform(get("/").with(httpBasic("user","password")))

Authorization: Basic dXNlcjpwYXNzd29yZA==

Spring MVC Test also provides a RequestBuilder interface that can be used to create the MockHttpServletRequest used in your test. Spring Security provides a few RequestBuilder implementations that can be used to make testing easier. In order to use Spring Security’s RequestBuilder implementations ensure the following static import is used:

import static org.springframework.security.test.web.servlet.request.SecurityMockMvcRequestBuilders.*;

mvc
	.perform(formLogin())

mvc
	.perform(formLogin("/auth").user("admin").password("pass"))

mvc
	.perform(formLogin("/auth").user("u","admin").password("p","pass"))

mvc
	.perform(logout())

mvc
	.perform(logout("/signout"))

At times it is desirable to make various security related assertions about a request. To accommodate this need, Spring Security Test support implements Spring MVC Test’s ResultMatcher interface. In order to use Spring Security’s ResultMatcher implementations ensure the following static import is used:

import static org.springframework.security.test.web.servlet.response.SecurityMockMvcResultMatchers.*;

mvc
	.perform(formLogin().password("invalid"))
	.andExpect(unauthenticated());

mvc
	.perform(formLogin())
	.andExpect(authenticated());

mvc
	.perform(formLogin().user("admin"))
	.andExpect(authenticated().withRoles("USER","ADMIN"));

mvc
	.perform(formLogin().user("admin"))
	.andExpect(authenticated().withUsername("admin"));

mvc
	.perform(formLogin().user("admin").roles("USER","ADMIN"))
	.andExpect(authenticated().withUsername("admin"));

When using servlet filters, you obviously need to declare them in your web.xml, or they will be ignored by the servlet container. In Spring Security, the filter classes are also Spring beans defined in the application context and thus able to take advantage of Spring’s rich dependency-injection facilities and lifecycle interfaces. Spring’s DelegatingFilterProxy provides the link between web.xml and the application context.

When using DelegatingFilterProxy, you will see something like this in the web.xml file:

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

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

Notice that the filter is actually a DelegatingFilterProxy, and not the class that will actually implement the logic of the filter. What DelegatingFilterProxy does is delegate the Filter 's methods through to a bean which is obtained from the Spring application context. This enables the bean to benefit from the Spring web application context lifecycle support and configuration flexibility. The bean must implement javax.servlet.Filter and it must have the same name as that in the filter-name element. Read the Javadoc for DelegatingFilterProxy for more information

Spring Security’s web infrastructure should only be used by delegating to an instance of FilterChainProxy. The security filters should not be used by themselves. In theory you could declare each Spring Security filter bean that you require in your application context file and add a corresponding DelegatingFilterProxy entry to web.xml for each filter, making sure that they are ordered correctly, but this would be cumbersome and would clutter up the web.xml file quickly if you have a lot of filters. FilterChainProxy lets us add a single entry to web.xml and deal entirely with the application context file for managing our web security beans. It is wired using a DelegatingFilterProxy, just like in the example above, but with the filter-name set to the bean name "filterChainProxy". The filter chain is then declared in the application context with the same bean name. Here’s an example:

<bean id="filterChainProxy" class="org.springframework.security.web.FilterChainProxy">
<constructor-arg>
	<list>
	<sec:filter-chain pattern="/restful/**" filters="
		securityContextPersistenceFilterWithASCFalse,
		basicAuthenticationFilter,
		exceptionTranslationFilter,
		filterSecurityInterceptor" />
	<sec:filter-chain pattern="/**" filters="
		securityContextPersistenceFilterWithASCTrue,
		formLoginFilter,
		exceptionTranslationFilter,
		filterSecurityInterceptor" />
	</list>
</constructor-arg>
</bean>

The namespace element filter-chain is used for convenience to set up the security filter chain(s) which are required within the application. ^[6]. It maps a particular URL pattern to a list of filters built up from the bean names specified in the filters element, and combines them in a bean of type SecurityFilterChain. The pattern attribute takes an Ant Paths and the most specific URIs should appear first ^[7]. At runtime the FilterChainProxy will locate the first URI pattern that matches the current web request and the list of filter beans specified by the filters attribute will be applied to that request. The filters will be invoked in the order they are defined, so you have complete control over the filter chain which is applied to a particular URL.

You may have noticed we have declared two SecurityContextPersistenceFilter s in the filter chain (ASC is short for allowSessionCreation, a property of SecurityContextPersistenceFilter). As web services will never present a jsessionid on future requests, creating HttpSession s for such user agents would be wasteful. If you had a high-volume application which required maximum scalability, we recommend you use the approach shown above. For smaller applications, using a single SecurityContextPersistenceFilter (with its default allowSessionCreation as true) would likely be sufficient.

Note that FilterChainProxy does not invoke standard filter lifecycle methods on the filters it is configured with. We recommend you use Spring’s application context lifecycle interfaces as an alternative, just as you would for any other Spring bean.

When we looked at how to set up web security using namespace configuration, we used a DelegatingFilterProxy with the name "springSecurityFilterChain". You should now be able to see that this is the name of the FilterChainProxy which is created by the namespace.

The order that filters are defined in the chain is very important. Irrespective of which filters you are actually using, the order should be as follows:

Spring Security has several areas where patterns you have defined are tested against incoming requests in order to decide how the request should be handled. This occurs when the FilterChainProxy decides which filter chain a request should be passed through and also when the FilterSecurityInterceptor decides which security constraints apply to a request. It’s important to understand what the mechanism is and what URL value is used when testing against the patterns that you define.

The Servlet Specification defines several properties for the HttpServletRequest which are accessible via getter methods, and which we might want to match against. These are the contextPath, servletPath, pathInfo and queryString. Spring Security is only interested in securing paths within the application, so the contextPath is ignored. Unfortunately, the servlet spec does not define exactly what the values of servletPath and pathInfo will contain for a particular request URI. For example, each path segment of a URL may contain parameters, as defined in RFC 2396 ^[8]. The Specification does not clearly state whether these should be included in the servletPath and pathInfo values and the behaviour varies between different servlet containers. There is a danger that when an application is deployed in a container which does not strip path parameters from these values, an attacker could add them to the requested URL in order to cause a pattern match to succeed or fail unexpectedly. ^[9]. Other variations in the incoming URL are also possible. For example, it could contain path-traversal sequences (like /../) or multiple forward slashes (//) which could also cause pattern-matches to fail. Some containers normalize these out before performing the servlet mapping, but others don’t. To protect against issues like these, FilterChainProxy uses an HttpFirewall strategy to check and wrap the request. Un-normalized requests are automatically rejected by default, and path parameters and duplicate slashes are removed for matching purposes. ^[10]. It is therefore essential that a FilterChainProxy is used to manage the security filter chain. Note that the servletPath and pathInfo values are decoded by the container, so your application should not have any valid paths which contain semi-colons, as these parts will be removed for matching purposes.

As mentioned above, the default strategy is to use Ant-style paths for matching and this is likely to be the best choice for most users. The strategy is implemented in the class AntPathRequestMatcher which uses Spring’s AntPathMatcher to perform a case-insensitive match of the pattern against the concatenated servletPath and pathInfo, ignoring the queryString.

If for some reason, you need a more powerful matching strategy, you can use regular expressions. The strategy implementation is then RegexRequestMatcher. See the Javadoc for this class for more information.

In practice we recommend that you use method security at your service layer, to control access to your application, and do not rely entirely on the use of security constraints defined at the web-application level. URLs change and it is difficult to take account of all the possible URLs that an application might support and how requests might be manipulated. You should try and restrict yourself to using a few simple ant paths which are simple to understand. Always try to use a "deny-by-default" approach where you have a catch-all wildcard ( / or ) defined last and denying access.

Security defined at the service layer is much more robust and harder to bypass, so you should always take advantage of Spring Security’s method security options.

The HttpFirewall also prevents HTTP Response Splitting by rejecting new line characters in the HTTP Response headers.

By default the StrictHttpFirewall is used. This implementation rejects requests that appear to be malicious. If it is too strict for your needs, then you can customize what types of requests are rejected. However, it is important that you do so knowing that this can open your application up to attacks. For example, if you wish to leverage Spring MVC’s Matrix Variables, the following configuration could be used in XML:

<b:bean id="httpFirewall"
      class="org.springframework.security.web.firewall.StrictHttpFirewall"
      p:allowSemicolon="true"/>

<http-firewall ref="httpFirewall"/>

The same thing can be achieved with Java Configuration by exposing a StrictHttpFirewall bean.

@Bean
public StrictHttpFirewall httpFirewall() {
    StrictHttpFirewall firewall = new StrictHttpFirewall();
    firewall.setAllowSemicolon(true);
    return firewall;
}

If you’re using some other framework that is also filter-based, then you need to make sure that the Spring Security filters come first. This enables the SecurityContextHolder to be populated in time for use by the other filters. Examples are the use of SiteMesh to decorate your web pages or a web framework like Wicket which uses a filter to handle its requests.

As we saw earlier in the namespace chapter, it’s possible to use multiple http elements to define different security configurations for different URL patterns. Each element creates a filter chain within the internal FilterChainProxy and the URL pattern that should be mapped to it. The elements will be added in the order they are declared, so the most specific patterns must again be declared first. Here’s another example, for a similar situation to that above, where the application supports both a stateless RESTful API and also a normal web application which users log into using a form.

<!-- Stateless RESTful service using Basic authentication -->
<http pattern="/restful/**" create-session="stateless">
<intercept-url pattern='/**' access="hasRole('REMOTE')" />
<http-basic />
</http>

<!-- Empty filter chain for the login page -->
<http pattern="/login.htm*" security="none"/>

<!-- Additional filter chain for normal users, matching all other requests -->
<http>
<intercept-url pattern='/**' access="hasRole('USER')" />
<form-login login-page='/login.htm' default-target-url="/home.htm"/>
<logout />
</http>

We’ve already seen FilterSecurityInterceptor briefly when discussing access-control in general, and we’ve already used it with the namespace where the <intercept-url> elements are combined to configure it internally. Now we’ll see how to explicitly configure it for use with a FilterChainProxy, along with its companion filter ExceptionTranslationFilter. A typical configuration example is shown below:

<bean id="filterSecurityInterceptor"
	class="org.springframework.security.web.access.intercept.FilterSecurityInterceptor">
<property name="authenticationManager" ref="authenticationManager"/>
<property name="accessDecisionManager" ref="accessDecisionManager"/>
<property name="securityMetadataSource">
	<security:filter-security-metadata-source>
	<security:intercept-url pattern="/secure/super/**" access="ROLE_WE_DONT_HAVE"/>
	<security:intercept-url pattern="/secure/**" access="ROLE_SUPERVISOR,ROLE_TELLER"/>
	</security:filter-security-metadata-source>
</property>
</bean>

FilterSecurityInterceptor is responsible for handling the security of HTTP resources. It requires a reference to an AuthenticationManager and an AccessDecisionManager. It is also supplied with configuration attributes that apply to different HTTP URL requests. Refer back to the original discussion on these in the technical introduction.

The FilterSecurityInterceptor can be configured with configuration attributes in two ways. The first, which is shown above, is using the <filter-security-metadata-source> namespace element. This is similar to the <http> element from the namespace chapter but the <intercept-url> child elements only use the pattern and access attributes. Commas are used to delimit the different configuration attributes that apply to each HTTP URL. The second option is to write your own SecurityMetadataSource, but this is beyond the scope of this document. Irrespective of the approach used, the SecurityMetadataSource is responsible for returning a List<ConfigAttribute> containing all of the configuration attributes associated with a single secure HTTP URL.

It should be noted that the FilterSecurityInterceptor.setSecurityMetadataSource() method actually expects an instance of FilterInvocationSecurityMetadataSource. This is a marker interface which subclasses SecurityMetadataSource. It simply denotes the SecurityMetadataSource understands FilterInvocation s. In the interests of simplicity we’ll continue to refer to the FilterInvocationSecurityMetadataSource as a SecurityMetadataSource, as the distinction is of little relevance to most users.

The SecurityMetadataSource created by the namespace syntax obtains the configuration attributes for a particular FilterInvocation by matching the request URL against the configured pattern attributes. This behaves in the same way as it does for namespace configuration. The default is to treat all expressions as Apache Ant paths and regular expressions are also supported for more complex cases. The request-matcher attribute is used to specify the type of pattern being used. It is not possible to mix expression syntaxes within the same definition. As an example, the previous configuration using regular expressions instead of Ant paths would be written as follows:

<bean id="filterInvocationInterceptor"
	class="org.springframework.security.web.access.intercept.FilterSecurityInterceptor">
<property name="authenticationManager" ref="authenticationManager"/>
<property name="accessDecisionManager" ref="accessDecisionManager"/>
<property name="runAsManager" ref="runAsManager"/>
<property name="securityMetadataSource">
	<security:filter-security-metadata-source request-matcher="regex">
	<security:intercept-url pattern="\A/secure/super/.*\Z" access="ROLE_WE_DONT_HAVE"/>
	<security:intercept-url pattern="\A/secure/.*\" access="ROLE_SUPERVISOR,ROLE_TELLER"/>
	</security:filter-security-metadata-source>
</property>
</bean>

Patterns are always evaluated in the order they are defined. Thus it is important that more specific patterns are defined higher in the list than less specific patterns. This is reflected in our example above, where the more specific /secure/super/ pattern appears higher than the less specific /secure/ pattern. If they were reversed, the /secure/ pattern would always match and the /secure/super/ pattern would never be evaluated.

The ExceptionTranslationFilter sits above the FilterSecurityInterceptor in the security filter stack. It doesn’t do any actual security enforcement itself, but handles exceptions thrown by the security interceptors and provides suitable and HTTP responses.

<bean id="exceptionTranslationFilter"
class="org.springframework.security.web.access.ExceptionTranslationFilter">
<property name="authenticationEntryPoint" ref="authenticationEntryPoint"/>
<property name="accessDeniedHandler" ref="accessDeniedHandler"/>
</bean>

<bean id="authenticationEntryPoint"
class="org.springframework.security.web.authentication.LoginUrlAuthenticationEntryPoint">
<property name="loginFormUrl" value="/login.jsp"/>
</bean>

<bean id="accessDeniedHandler"
	class="org.springframework.security.web.access.AccessDeniedHandlerImpl">
<property name="errorPage" value="/accessDenied.htm"/>
</bean>

We covered the purpose of this all-important filter in the Technical Overview chapter so you might want to re-read that section at this point. Let’s first take a look at how you would configure it for use with a FilterChainProxy. A basic configuration only requires the bean itself

<bean id="securityContextPersistenceFilter"
class="org.springframework.security.web.context.SecurityContextPersistenceFilter"/>

As we saw previously, this filter has two main tasks. It is responsible for storage of the SecurityContext contents between HTTP requests and for clearing the SecurityContextHolder when a request is completed. Clearing the ThreadLocal in which the context is stored is essential, as it might otherwise be possible for a thread to be replaced into the servlet container’s thread pool, with the security context for a particular user still attached. This thread might then be used at a later stage, performing operations with the wrong credentials.

public interface SecurityContextRepository {

SecurityContext loadContext(HttpRequestResponseHolder requestResponseHolder);

void saveContext(SecurityContext context, HttpServletRequest request,
		HttpServletResponse response);
}

<bean id="securityContextPersistenceFilter"
	class="org.springframework.security.web.context.SecurityContextPersistenceFilter">
<property name='securityContextRepository'>
	<bean class='org.springframework.security.web.context.HttpSessionSecurityContextRepository'>
	<property name='allowSessionCreation' value='false' />
	</bean>
</property>
</bean>

We’ve now seen the three main filters which are always present in a Spring Security web configuration. These are also the three which are automatically created by the namespace <http> element and cannot be substituted with alternatives. The only thing that’s missing now is an actual authentication mechanism, something that will allow a user to authenticate. This filter is the most commonly used authentication filter and the one that is most often customized ^[13]. It also provides the implementation used by the <form-login> element from the namespace. There are three stages required to configure it.

The login form simply contains username and password input fields, and posts to the URL that is monitored by the filter (by default this is /login). The basic filter configuration looks something like this:

<bean id="authenticationFilter" class=
"org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter">
<property name="authenticationManager" ref="authenticationManager"/>
</bean>

14.4.1 Application Flow on Authentication Success and Failure

The filter calls the configured AuthenticationManager to process each authentication request. The destination following a successful authentication or an authentication failure is controlled by the AuthenticationSuccessHandler and AuthenticationFailureHandler strategy interfaces, respectively. The filter has properties which allow you to set these so you can customize the behaviour completely ^[14]. Some standard implementations are supplied such as SimpleUrlAuthenticationSuccessHandler, SavedRequestAwareAuthenticationSuccessHandler, SimpleUrlAuthenticationFailureHandler, ExceptionMappingAuthenticationFailureHandler and DelegatingAuthenticationFailureHandler. Have a look at the Javadoc for these classes and also for AbstractAuthenticationProcessingFilter to get an overview of how they work and the supported features.

If authentication is successful, the resulting Authentication object will be placed into the SecurityContextHolder. The configured AuthenticationSuccessHandler will then be called to either redirect or forward the user to the appropriate destination. By default a SavedRequestAwareAuthenticationSuccessHandler is used, which means that the user will be redirected to the original destination they requested before they were asked to login.

	Note
	The ExceptionTranslationFilter caches the original request a user makes. When the user authenticates, the request handler makes use of this cached request to obtain the original URL and redirect to it. The original request is then rebuilt and used as an alternative.

If authentication fails, the configured AuthenticationFailureHandler will be invoked.

The following section describes the Servlet 3 methods that Spring Security integrates with.

15.2.2 HttpServletRequest.login(String,String)

The HttpServletRequest.login(String,String) method can be used to authenticate the user with the current AuthenticationManager. For example, the following would attempt to authenticate with the username "user" and password "password":

try {
httpServletRequest.login("user","password");
} catch(ServletException e) {
// fail to authenticate
}

	Note
	It is not necessary to catch the ServletException if you want Spring Security to process the failed authentication attempt.

final AsyncContext async = httpServletRequest.startAsync();
async.start(new Runnable() {
	public void run() {
		Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
		try {
			final HttpServletResponse asyncResponse = (HttpServletResponse) async.getResponse();
			asyncResponse.setStatus(HttpServletResponse.SC_OK);
			asyncResponse.getWriter().write(String.valueOf(authentication));
			async.complete();
		} catch(Exception e) {
			throw new RuntimeException(e);
		}
	}
});

<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">

</web-app>

<filter>
<filter-name>springSecurityFilterChain</filter-name>
<filter-class>
	org.springframework.web.filter.DelegatingFilterProxy
</filter-class>
<async-supported>true</async-supported>
</filter>
<filter-mapping>
<filter-name>springSecurityFilterChain</filter-name>
<url-pattern>/*</url-pattern>
<dispatcher>REQUEST</dispatcher>
<dispatcher>ASYNC</dispatcher>
</filter-mapping>

httpServletRequest.startAsync();
new Thread("AsyncThread") {
	@Override
	public void run() {
		try {
			// Do work
			TimeUnit.SECONDS.sleep(1);

			// Write to and commit the httpServletResponse
			httpServletResponse.getOutputStream().flush();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}.start();

The following section describes the Servlet 3.1 methods that Spring Security integrates with.

BasicAuthenticationFilter is responsible for processing basic authentication credentials presented in HTTP headers. This can be used for authenticating calls made by Spring remoting protocols (such as Hessian and Burlap), as well as normal browser user agents (such as Firefox and Internet Explorer). The standard governing HTTP Basic Authentication is defined by RFC 1945, Section 11, and BasicAuthenticationFilter conforms with this RFC. Basic Authentication is an attractive approach to authentication, because it is very widely deployed in user agents and implementation is extremely simple (it’s just a Base64 encoding of the username:password, specified in an HTTP header).

<bean id="basicAuthenticationFilter"
class="org.springframework.security.web.authentication.www.BasicAuthenticationFilter">
<property name="authenticationManager" ref="authenticationManager"/>
<property name="authenticationEntryPoint" ref="authenticationEntryPoint"/>
</bean>

<bean id="authenticationEntryPoint"
class="org.springframework.security.web.authentication.www.BasicAuthenticationEntryPoint">
<property name="realmName" value="Name Of Your Realm"/>
</bean>

DigestAuthenticationFilter is capable of processing digest authentication credentials presented in HTTP headers. Digest Authentication attempts to solve many of the weaknesses of Basic authentication, specifically by ensuring credentials are never sent in clear text across the wire. Many user agents support Digest Authentication, including Mozilla Firefox and Internet Explorer. The standard governing HTTP Digest Authentication is defined by RFC 2617, which updates an earlier version of the Digest Authentication standard prescribed by RFC 2069. Most user agents implement RFC 2617. Spring Security’s DigestAuthenticationFilter is compatible with the “auth” quality of protection (qop) prescribed by RFC 2617, which also provides backward compatibility with RFC 2069. Digest Authentication is a more attractive option if you need to use unencrypted HTTP (i.e. no TLS/HTTPS) and wish to maximise security of the authentication process. Indeed Digest Authentication is a mandatory requirement for the WebDAV protocol, as noted by RFC 2518 Section 17.1.

	Note
	You should not use Digest in modern applications because it is not considered secure. The most obvious problem is that you must store your passwords in plaintext, encrypted, or an MD5 format. All of these storage formats are considered insecure. Instead, you should use a one way adaptive password hash (i.e. bCrypt, PBKDF2, SCrypt, etc).

Central to Digest Authentication is a "nonce". This is a value the server generates. Spring Security’s nonce adopts the following format:

base64(expirationTime + ":" + md5Hex(expirationTime + ":" + key))
expirationTime:   The date and time when the nonce expires, expressed in milliseconds
key:              A private key to prevent modification of the nonce token

The DigestAuthenticationEntryPoint has a property specifying the key used for generating the nonce tokens, along with a nonceValiditySeconds property for determining the expiration time (default 300, which equals five minutes). Whist ever the nonce is valid, the digest is computed by concatenating various strings including the username, password, nonce, URI being requested, a client-generated nonce (merely a random value which the user agent generates each request), the realm name etc, then performing an MD5 hash. Both the server and user agent perform this digest computation, resulting in different hash codes if they disagree on an included value (eg password). In Spring Security implementation, if the server-generated nonce has merely expired (but the digest was otherwise valid), the DigestAuthenticationEntryPoint will send a "stale=true" header. This tells the user agent there is no need to disturb the user (as the password and username etc is correct), but simply to try again using a new nonce.

An appropriate value for the nonceValiditySeconds parameter of DigestAuthenticationEntryPoint depends on your application. Extremely secure applications should note that an intercepted authentication header can be used to impersonate the principal until the expirationTime contained in the nonce is reached. This is the key principle when selecting an appropriate setting, but it would be unusual for immensely secure applications to not be running over TLS/HTTPS in the first instance.

Because of the more complex implementation of Digest Authentication, there are often user agent issues. For example, Internet Explorer fails to present an “opaque” token on subsequent requests in the same session. Spring Security filters therefore encapsulate all state information into the “nonce” token instead. In our testing, Spring Security’s implementation works reliably with Mozilla Firefox and Internet Explorer, correctly handling nonce timeouts etc.

<bean id="digestFilter" class=
	"org.springframework.security.web.authentication.www.DigestAuthenticationFilter">
<property name="userDetailsService" ref="jdbcDaoImpl"/>
<property name="authenticationEntryPoint" ref="digestEntryPoint"/>
<property name="userCache" ref="userCache"/>
</bean>

<bean id="digestEntryPoint" class=
	"org.springframework.security.web.authentication.www.DigestAuthenticationEntryPoint">
<property name="realmName" value="Contacts Realm via Digest Authentication"/>
<property name="key" value="acegi"/>
<property name="nonceValiditySeconds" value="10"/>
</bean>