spring-security/docs/modules/ROOT/pages/servlet/oauth2/login/advanced.adoc

[[oauth2login-advanced]]
= Advanced Configuration

`HttpSecurity.oauth2Login()` provides a number of configuration options for customizing OAuth 2.0 Login.
The main configuration options are grouped into their protocol endpoint counterparts.

For example, `oauth2Login().authorizationEndpoint()` allows configuring the _Authorization Endpoint_, whereas `oauth2Login().tokenEndpoint()` allows configuring the _Token Endpoint_.

The following code shows an example:

.Advanced OAuth2 Login Configuration
====
.Java
[source,java,role="primary"]
----
@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

	@Override
	protected void configure(HttpSecurity http) throws Exception {
		http
			.oauth2Login(oauth2 -> oauth2
			    .authorizationEndpoint(authorization -> authorization
			            ...
			    )
			    .redirectionEndpoint(redirection -> redirection
			            ...
			    )
			    .tokenEndpoint(token -> token
			            ...
			    )
			    .userInfoEndpoint(userInfo -> userInfo
			            ...
			    )
			);
	}
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@EnableWebSecurity
class OAuth2LoginSecurityConfig : WebSecurityConfigurerAdapter() {

    override fun configure(http: HttpSecurity) {
        http {
            oauth2Login {
                authorizationEndpoint {
                    ...
                }
                redirectionEndpoint {
                    ...
                }
                tokenEndpoint {
                    ...
                }
                userInfoEndpoint {
                    ...
                }
            }
        }
    }
}
----
====

The main goal of the `oauth2Login()` DSL was to closely align with the naming, as defined in the specifications.

The OAuth 2.0 Authorization Framework defines the https://tools.ietf.org/html/rfc6749#section-3[Protocol Endpoints] as follows:

The authorization process uses two authorization server endpoints (HTTP resources):

* Authorization Endpoint: Used by the client to obtain authorization from the resource owner through user-agent redirection.
* Token Endpoint: Used by the client to exchange an authorization grant for an access token, typically with client authentication.

The authorization process also uses one client endpoint:

* Redirection Endpoint: Used by the authorization server to return responses that contain authorization credentials to the client through the resource owner user-agent.

The OpenID Connect Core 1.0 specification defines the https://openid.net/specs/openid-connect-core-1_0.html#UserInfo[UserInfo Endpoint] as follows:

The UserInfo Endpoint is an OAuth 2.0 Protected Resource that returns claims about the authenticated end-user.
To obtain the requested claims about the end-user, the client makes a request to the UserInfo Endpoint by using an access token obtained through OpenID Connect Authentication.
These claims are normally represented by a JSON object that contains a collection of name-value pairs for the claims.

The following code shows the complete configuration options available for the `oauth2Login()` DSL:

.OAuth2 Login Configuration Options
====
.Java
[source,java,role="primary"]
----
@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

	@Override
	protected void configure(HttpSecurity http) throws Exception {
		http
			.oauth2Login(oauth2 -> oauth2
			    .clientRegistrationRepository(this.clientRegistrationRepository())
			    .authorizedClientRepository(this.authorizedClientRepository())
			    .authorizedClientService(this.authorizedClientService())
			    .loginPage("/login")
			    .authorizationEndpoint(authorization -> authorization
			        .baseUri(this.authorizationRequestBaseUri())
			        .authorizationRequestRepository(this.authorizationRequestRepository())
			        .authorizationRequestResolver(this.authorizationRequestResolver())
			    )
			    .redirectionEndpoint(redirection -> redirection
			        .baseUri(this.authorizationResponseBaseUri())
			    )
			    .tokenEndpoint(token -> token
			        .accessTokenResponseClient(this.accessTokenResponseClient())
			    )
			    .userInfoEndpoint(userInfo -> userInfo
			        .userAuthoritiesMapper(this.userAuthoritiesMapper())
			        .userService(this.oauth2UserService())
			        .oidcUserService(this.oidcUserService())
			    )
			);
	}
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@EnableWebSecurity
class OAuth2LoginSecurityConfig : WebSecurityConfigurerAdapter() {

    override fun configure(http: HttpSecurity) {
        http {
            oauth2Login {
                clientRegistrationRepository = clientRegistrationRepository()
                authorizedClientRepository = authorizedClientRepository()
                authorizedClientService = authorizedClientService()
                loginPage = "/login"
                authorizationEndpoint {
                    baseUri = authorizationRequestBaseUri()
                    authorizationRequestRepository = authorizationRequestRepository()
                    authorizationRequestResolver = authorizationRequestResolver()
                }
                redirectionEndpoint {
                    baseUri = authorizationResponseBaseUri()
                }
                tokenEndpoint {
                    accessTokenResponseClient = accessTokenResponseClient()
                }
                userInfoEndpoint {
                    userAuthoritiesMapper = userAuthoritiesMapper()
                    userService = oauth2UserService()
                    oidcUserService = oidcUserService()
                }
            }
        }
    }
}
----
====

In addition to the `oauth2Login()` DSL, XML configuration is also supported.

The following code shows the complete configuration options available in the xref:servlet/appendix/namespace/http.adoc#nsa-oauth2-login[ security namespace]:

.OAuth2 Login XML Configuration Options
====
[source,xml]
----
<http>
	<oauth2-login client-registration-repository-ref="clientRegistrationRepository"
				  authorized-client-repository-ref="authorizedClientRepository"
				  authorized-client-service-ref="authorizedClientService"
				  authorization-request-repository-ref="authorizationRequestRepository"
				  authorization-request-resolver-ref="authorizationRequestResolver"
				  access-token-response-client-ref="accessTokenResponseClient"
				  user-authorities-mapper-ref="userAuthoritiesMapper"
				  user-service-ref="oauth2UserService"
				  oidc-user-service-ref="oidcUserService"
				  login-processing-url="/login/oauth2/code/*"
				  login-page="/login"
				  authentication-success-handler-ref="authenticationSuccessHandler"
				  authentication-failure-handler-ref="authenticationFailureHandler"
				  jwt-decoder-factory-ref="jwtDecoderFactory"/>
</http>
----
====

The following sections go into more detail on each of the configuration options available:

* <<oauth2login-advanced-login-page>>
* <<oauth2login-advanced-redirection-endpoint>>
* <<oauth2login-advanced-userinfo-endpoint>>
* <<oauth2login-advanced-idtoken-verify>>
* <<oauth2login-advanced-oidc-logout>>


[[oauth2login-advanced-login-page]]
== OAuth 2.0 Login Page

By default, the OAuth 2.0 Login Page is auto-generated by the `DefaultLoginPageGeneratingFilter`.
The default login page shows each configured OAuth Client with its `ClientRegistration.clientName` as a link, which is capable of initiating the Authorization Request (or OAuth 2.0 Login).

[NOTE]
====
For `DefaultLoginPageGeneratingFilter` to show links for configured OAuth Clients, the registered `ClientRegistrationRepository` needs to also implement `Iterable<ClientRegistration>`.
See `InMemoryClientRegistrationRepository` for reference.
====

The link's destination for each OAuth Client defaults to the following:

`+OAuth2AuthorizationRequestRedirectFilter.DEFAULT_AUTHORIZATION_REQUEST_BASE_URI + "/{registrationId}"+`

The following line shows an example:

====
[source,html]
----
<a href="/oauth2/authorization/google">Google</a>
----
====

To override the default login page, configure `oauth2Login().loginPage()` and (optionally) `oauth2Login().authorizationEndpoint().baseUri()`.

The following listing shows an example:

.OAuth2 Login Page Configuration
====
.Java
[source,java,role="primary"]
----
@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

	@Override
	protected void configure(HttpSecurity http) throws Exception {
		http
			.oauth2Login(oauth2 -> oauth2
			    .loginPage("/login/oauth2")
			    ...
			    .authorizationEndpoint(authorization -> authorization
			        .baseUri("/login/oauth2/authorization")
			        ...
			    )
			);
	}
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@EnableWebSecurity
class OAuth2LoginSecurityConfig : WebSecurityConfigurerAdapter() {

    override fun configure(http: HttpSecurity) {
        http {
            oauth2Login {
                loginPage = "/login/oauth2"
                authorizationEndpoint {
                    baseUri = "/login/oauth2/authorization"
                }
            }
        }
    }
}
----

.Xml
[source,xml,role="secondary"]
----
<http>
	<oauth2-login login-page="/login/oauth2"
				  ...
    />
</http>
----
====

[IMPORTANT]
====
You need to provide a `@Controller` with a `@RequestMapping("/login/oauth2")` that is capable of rendering the custom login page.
====

[TIP]
=====
As noted earlier, configuring `oauth2Login().authorizationEndpoint().baseUri()` is optional.
However, if you choose to customize it, ensure the link to each OAuth Client matches the `authorizationEndpoint().baseUri()`.

The following line shows an example:
====
[source,html]
----
<a href="/login/oauth2/authorization/google">Google</a>
----
====
=====


[[oauth2login-advanced-redirection-endpoint]]
== Redirection Endpoint

The Redirection Endpoint is used by the Authorization Server for returning the Authorization Response (which contains the authorization credentials) to the client through the Resource Owner user-agent.

[TIP]
====
OAuth 2.0 Login leverages the Authorization Code Grant.
Therefore, the authorization credential is the authorization code.
====

The default Authorization Response `baseUri` (redirection endpoint) is `*/login/oauth2/code/**`, which is defined in `OAuth2LoginAuthenticationFilter.DEFAULT_FILTER_PROCESSES_URI`.

If you would like to customize the Authorization Response `baseUri`, configure it as follows:

.Redirection Endpoint Configuration
====
.Java
[source,java,role="primary"]
----
@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

	@Override
	protected void configure(HttpSecurity http) throws Exception {
		http
			.oauth2Login(oauth2 -> oauth2
			    .redirectionEndpoint(redirection -> redirection
			        .baseUri("/login/oauth2/callback/*")
			        ...
			    )
			);
	}
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@EnableWebSecurity
class OAuth2LoginSecurityConfig : WebSecurityConfigurerAdapter() {

    override fun configure(http: HttpSecurity) {
        http {
            oauth2Login {
                redirectionEndpoint {
                    baseUri = "/login/oauth2/callback/*"
                }
            }
        }
    }
}
----

.Xml
[source,xml,role="secondary"]
----
<http>
	<oauth2-login login-processing-url="/login/oauth2/callback/*"
				  ...
    />
</http>
----
====

[IMPORTANT]
=====
You also need to ensure the `ClientRegistration.redirectUri` matches the custom Authorization Response `baseUri`.

The following listing shows an example:

====
.Java
[source,java,role="primary",subs="-attributes"]
----
return CommonOAuth2Provider.GOOGLE.getBuilder("google")
	.clientId("google-client-id")
	.clientSecret("google-client-secret")
	.redirectUri("{baseUrl}/login/oauth2/callback/{registrationId}")
	.build();
----

.Kotlin
[source,kotlin,role="secondary",subs="-attributes"]
----
return CommonOAuth2Provider.GOOGLE.getBuilder("google")
    .clientId("google-client-id")
    .clientSecret("google-client-secret")
    .redirectUri("{baseUrl}/login/oauth2/callback/{registrationId}")
    .build()
----
====
=====


[[oauth2login-advanced-userinfo-endpoint]]
== UserInfo Endpoint

The UserInfo Endpoint includes a number of configuration options, as described in the following sub-sections:

* <<oauth2login-advanced-map-authorities>>
* <<oauth2login-advanced-oauth2-user-service>>
* <<oauth2login-advanced-oidc-user-service>>


[[oauth2login-advanced-map-authorities]]
=== Mapping User Authorities

After the user successfully authenticates with the OAuth 2.0 Provider, the `OAuth2User.getAuthorities()` (or `OidcUser.getAuthorities()`) can be mapped to a new set of `GrantedAuthority` instances, which are supplied to `OAuth2AuthenticationToken` when completing the authentication.

[TIP]
`OAuth2AuthenticationToken.getAuthorities()` is used for authorizing requests, such as in `hasRole('USER')` or `hasRole('ADMIN')`.

There are a couple of options to choose from when mapping user authorities:

* <<oauth2login-advanced-map-authorities-grantedauthoritiesmapper>>
* <<oauth2login-advanced-map-authorities-oauth2userservice>>


[[oauth2login-advanced-map-authorities-grantedauthoritiesmapper]]
==== Using a GrantedAuthoritiesMapper

Provide an implementation of `GrantedAuthoritiesMapper` and configure it, as follows:

.Granted Authorities Mapper Configuration
====
.Java
[source,java,role="primary"]
----
@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

	@Override
	protected void configure(HttpSecurity http) throws Exception {
		http
			.oauth2Login(oauth2 -> oauth2
			    .userInfoEndpoint(userInfo -> userInfo
			        .userAuthoritiesMapper(this.userAuthoritiesMapper())
			        ...
			    )
			);
	}

	private GrantedAuthoritiesMapper userAuthoritiesMapper() {
		return (authorities) -> {
			Set<GrantedAuthority> mappedAuthorities = new HashSet<>();

			authorities.forEach(authority -> {
				if (OidcUserAuthority.class.isInstance(authority)) {
					OidcUserAuthority oidcUserAuthority = (OidcUserAuthority)authority;

					OidcIdToken idToken = oidcUserAuthority.getIdToken();
					OidcUserInfo userInfo = oidcUserAuthority.getUserInfo();

					// Map the claims found in idToken and/or userInfo
					// to one or more GrantedAuthority's and add it to mappedAuthorities

				} else if (OAuth2UserAuthority.class.isInstance(authority)) {
					OAuth2UserAuthority oauth2UserAuthority = (OAuth2UserAuthority)authority;

					Map<String, Object> userAttributes = oauth2UserAuthority.getAttributes();

					// Map the attributes found in userAttributes
					// to one or more GrantedAuthority's and add it to mappedAuthorities

				}
			});

			return mappedAuthorities;
		};
	}
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@EnableWebSecurity
class OAuth2LoginSecurityConfig : WebSecurityConfigurerAdapter() {

    override fun configure(http: HttpSecurity) {
        http {
            oauth2Login {
                userInfoEndpoint {
                    userAuthoritiesMapper = userAuthoritiesMapper()
                }
            }
        }
    }

    private fun userAuthoritiesMapper(): GrantedAuthoritiesMapper = GrantedAuthoritiesMapper { authorities: Collection<GrantedAuthority> ->
        val mappedAuthorities = emptySet<GrantedAuthority>()

        authorities.forEach { authority ->
            if (authority is OidcUserAuthority) {
                val idToken = authority.idToken
                val userInfo = authority.userInfo
                // Map the claims found in idToken and/or userInfo
                // to one or more GrantedAuthority's and add it to mappedAuthorities
            } else if (authority is OAuth2UserAuthority) {
                val userAttributes = authority.attributes
                // Map the attributes found in userAttributes
                // to one or more GrantedAuthority's and add it to mappedAuthorities
            }
        }

        mappedAuthorities
    }
}
----

.Xml
[source,xml,role="secondary"]
----
<http>
	<oauth2-login user-authorities-mapper-ref="userAuthoritiesMapper"
				  ...
    />
</http>
----
====

Alternatively, you can register a `GrantedAuthoritiesMapper` `@Bean` to have it automatically applied to the configuration, as follows:

.Granted Authorities Mapper Bean Configuration
====
.Java
[source,java,role="primary"]
----
@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

	@Override
	protected void configure(HttpSecurity http) throws Exception {
		http
		    .oauth2Login(withDefaults());
	}

	@Bean
	public GrantedAuthoritiesMapper userAuthoritiesMapper() {
		...
	}
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@EnableWebSecurity
class OAuth2LoginSecurityConfig : WebSecurityConfigurerAdapter() {

    override fun configure(http: HttpSecurity) {
        http {
            oauth2Login { }
        }
    }

    @Bean
    fun userAuthoritiesMapper(): GrantedAuthoritiesMapper {
        ...
    }
}
----
====

[[oauth2login-advanced-map-authorities-oauth2userservice]]
==== Delegation-based Strategy with OAuth2UserService

This strategy is advanced compared to using a `GrantedAuthoritiesMapper`. However, it is also more flexible, as it gives you access to the `OAuth2UserRequest` and `OAuth2User` (when using an OAuth 2.0 UserService) or `OidcUserRequest` and `OidcUser` (when using an OpenID Connect 1.0 UserService).

The `OAuth2UserRequest` (and `OidcUserRequest`) provides you access to the associated `OAuth2AccessToken`, which is very useful in cases where the _delegator_ needs to fetch authority information from a protected resource before it can map the custom authorities for the user.

The following example shows how to implement and configure a delegation-based strategy using an OpenID Connect 1.0 UserService:

.OAuth2UserService Configuration
====
.Java
[source,java,role="primary"]
----
@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

	@Override
	protected void configure(HttpSecurity http) throws Exception {
		http
			.oauth2Login(oauth2 -> oauth2
			    .userInfoEndpoint(userInfo -> userInfo
			        .oidcUserService(this.oidcUserService())
			        ...
			    )
			);
	}

	private OAuth2UserService<OidcUserRequest, OidcUser> oidcUserService() {
		final OidcUserService delegate = new OidcUserService();

		return (userRequest) -> {
			// Delegate to the default implementation for loading a user
			OidcUser oidcUser = delegate.loadUser(userRequest);

			OAuth2AccessToken accessToken = userRequest.getAccessToken();
			Set<GrantedAuthority> mappedAuthorities = new HashSet<>();

			// TODO
			// 1) Fetch the authority information from the protected resource using accessToken
			// 2) Map the authority information to one or more GrantedAuthority's and add it to mappedAuthorities

			// 3) Create a copy of oidcUser but use the mappedAuthorities instead
			oidcUser = new DefaultOidcUser(mappedAuthorities, oidcUser.getIdToken(), oidcUser.getUserInfo());

			return oidcUser;
		};
	}
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@EnableWebSecurity
class OAuth2LoginSecurityConfig : WebSecurityConfigurerAdapter() {

    override fun configure(http: HttpSecurity) {
        http {
            oauth2Login {
                userInfoEndpoint {
                    oidcUserService = oidcUserService()
                }
            }
        }
    }

    @Bean
    fun oidcUserService(): OAuth2UserService<OidcUserRequest, OidcUser> {
        val delegate = OidcUserService()

        return OAuth2UserService { userRequest ->
            // Delegate to the default implementation for loading a user
            var oidcUser = delegate.loadUser(userRequest)

            val accessToken = userRequest.accessToken
            val mappedAuthorities = HashSet<GrantedAuthority>()

            // TODO
            // 1) Fetch the authority information from the protected resource using accessToken
            // 2) Map the authority information to one or more GrantedAuthority's and add it to mappedAuthorities
            // 3) Create a copy of oidcUser but use the mappedAuthorities instead
            oidcUser = DefaultOidcUser(mappedAuthorities, oidcUser.idToken, oidcUser.userInfo)

            oidcUser
        }
    }
}
----

.Xml
[source,xml,role="secondary"]
----
<http>
	<oauth2-login oidc-user-service-ref="oidcUserService"
				  ...
    />
</http>
----
====


[[oauth2login-advanced-oauth2-user-service]]
=== OAuth 2.0 UserService

`DefaultOAuth2UserService` is an implementation of an `OAuth2UserService` that supports standard OAuth 2.0 Provider's.

[NOTE]
====
`OAuth2UserService` obtains the user attributes of the end-user (the resource owner) from the UserInfo Endpoint (by using the access token granted to the client during the authorization flow) and returns an `AuthenticatedPrincipal` in the form of an `OAuth2User`.
====

`DefaultOAuth2UserService` uses a `RestOperations` instance when requesting the user attributes at the UserInfo Endpoint.

If you need to customize the pre-processing of the UserInfo Request, you can provide `DefaultOAuth2UserService.setRequestEntityConverter()` with a custom `Converter<OAuth2UserRequest, RequestEntity<?>>`.
The default implementation `OAuth2UserRequestEntityConverter` builds a `RequestEntity` representation of a UserInfo Request that sets the `OAuth2AccessToken` in the `Authorization` header by default.

On the other end, if you need to customize the post-handling of the UserInfo Response, you need to provide `DefaultOAuth2UserService.setRestOperations()` with a custom configured `RestOperations`.
The default `RestOperations` is configured as follows:

====
[source,java]
----
RestTemplate restTemplate = new RestTemplate();
restTemplate.setErrorHandler(new OAuth2ErrorResponseErrorHandler());
----
====

`OAuth2ErrorResponseErrorHandler` is a `ResponseErrorHandler` that can handle an OAuth 2.0 Error (400 Bad Request).
It uses an `OAuth2ErrorHttpMessageConverter` for converting the OAuth 2.0 Error parameters to an `OAuth2Error`.

Whether you customize `DefaultOAuth2UserService` or provide your own implementation of `OAuth2UserService`, you need to configure it as follows:

====
.Java
[source,java,role="primary"]
----
@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

	@Override
	protected void configure(HttpSecurity http) throws Exception {
		http
			.oauth2Login(oauth2 -> oauth2
			    .userInfoEndpoint(userInfo -> userInfo
			        .userService(this.oauth2UserService())
			        ...
			    )
			);
	}

	private OAuth2UserService<OAuth2UserRequest, OAuth2User> oauth2UserService() {
		...
	}
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@EnableWebSecurity
class OAuth2LoginSecurityConfig : WebSecurityConfigurerAdapter() {

    override fun configure(http: HttpSecurity) {
        http {
            oauth2Login {
                userInfoEndpoint {
                    userService = oauth2UserService()
                    // ...
                }
            }
        }
    }

    private fun oauth2UserService(): OAuth2UserService<OAuth2UserRequest, OAuth2User> {
        // ...
    }
}
----
====


[[oauth2login-advanced-oidc-user-service]]
=== OpenID Connect 1.0 UserService

`OidcUserService` is an implementation of an `OAuth2UserService` that supports OpenID Connect 1.0 Provider's.

The `OidcUserService` leverages the `DefaultOAuth2UserService` when requesting the user attributes at the UserInfo Endpoint.

If you need to customize the pre-processing of the UserInfo Request or the post-handling of the UserInfo Response, you need to provide `OidcUserService.setOauth2UserService()` with a custom configured `DefaultOAuth2UserService`.

Whether you customize `OidcUserService` or provide your own implementation of `OAuth2UserService` for OpenID Connect 1.0 Provider's, you need to configure it as follows:

====
.Java
[source,java,role="primary"]
----
@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

	@Override
	protected void configure(HttpSecurity http) throws Exception {
		http
			.oauth2Login(oauth2 -> oauth2
				.userInfoEndpoint(userInfo -> userInfo
				    .oidcUserService(this.oidcUserService())
				    ...
			    )
			);
	}

	private OAuth2UserService<OidcUserRequest, OidcUser> oidcUserService() {
		...
	}
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@EnableWebSecurity
class OAuth2LoginSecurityConfig : WebSecurityConfigurerAdapter() {

    override fun configure(http: HttpSecurity) {
        http {
            oauth2Login {
                userInfoEndpoint {
                    oidcUserService = oidcUserService()
                    // ...
                }
            }
        }
    }

    private fun oidcUserService(): OAuth2UserService<OidcUserRequest, OidcUser> {
        // ...
    }
}
----
====


[[oauth2login-advanced-idtoken-verify]]
== ID Token Signature Verification

OpenID Connect 1.0 Authentication introduces the https://openid.net/specs/openid-connect-core-1_0.html#IDToken[ID Token], which is a security token that contains Claims about the Authentication of an End-User by an Authorization Server when used by a Client.

The ID Token is represented as a https://tools.ietf.org/html/rfc7519[JSON Web Token] (JWT) and MUST be signed by using https://tools.ietf.org/html/rfc7515[JSON Web Signature] (JWS).

The `OidcIdTokenDecoderFactory` provides a `JwtDecoder` used for `OidcIdToken` signature verification. The default algorithm is `RS256` but may be different when assigned during client registration.
For these cases, you can configure a resolver to return the expected JWS algorithm assigned for a specific client.

The JWS algorithm resolver is a `Function` that accepts a `ClientRegistration` and returns the expected `JwsAlgorithm` for the client, such as `SignatureAlgorithm.RS256` or `MacAlgorithm.HS256`

The following code shows how to configure the `OidcIdTokenDecoderFactory` `@Bean` to default to `MacAlgorithm.HS256` for all `ClientRegistration` instances:

====
.Java
[source,java,role="primary"]
----
@Bean
public JwtDecoderFactory<ClientRegistration> idTokenDecoderFactory() {
	OidcIdTokenDecoderFactory idTokenDecoderFactory = new OidcIdTokenDecoderFactory();
	idTokenDecoderFactory.setJwsAlgorithmResolver(clientRegistration -> MacAlgorithm.HS256);
	return idTokenDecoderFactory;
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Bean
fun idTokenDecoderFactory(): JwtDecoderFactory<ClientRegistration?> {
    val idTokenDecoderFactory = OidcIdTokenDecoderFactory()
    idTokenDecoderFactory.setJwsAlgorithmResolver { MacAlgorithm.HS256 }
    return idTokenDecoderFactory
}
----
====

[NOTE]
====
For MAC-based algorithms (such as `HS256`, `HS384`, or `HS512`), the `client-secret` that corresponds to the `client-id` is used as the symmetric key for signature verification.
====

[TIP]
====
If more than one `ClientRegistration` is configured for OpenID Connect 1.0 Authentication, the JWS algorithm resolver may evaluate the provided `ClientRegistration` to determine which algorithm to return.
====


[[oauth2login-advanced-oidc-logout]]
== OpenID Connect 1.0 Logout

OpenID Connect Session Management 1.0 allows the ability to log out the end user at the Provider by using the Client.
One of the strategies available is https://openid.net/specs/openid-connect-session-1_0.html#RPLogout[RP-Initiated Logout].

If the OpenID Provider supports both Session Management and https://openid.net/specs/openid-connect-discovery-1_0.html[Discovery], the client can obtain the `end_session_endpoint` `URL` from the OpenID Provider's https://openid.net/specs/openid-connect-session-1_0.html#OPMetadata[Discovery Metadata].
You can do so by configuring the `ClientRegistration` with the `issuer-uri`, as follows:

====
[source,yaml]
----
spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            client-id: okta-client-id
            client-secret: okta-client-secret
            ...
        provider:
          okta:
            issuer-uri: https://dev-1234.oktapreview.com
----
====

Also, you can configure `OidcClientInitiatedLogoutSuccessHandler`, which implements RP-Initiated Logout, as follows:

====
.Java
[source,java,role="primary"]
----
@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

	@Autowired
	private ClientRegistrationRepository clientRegistrationRepository;

	@Override
	protected void configure(HttpSecurity http) throws Exception {
		http
			.authorizeHttpRequests(authorize -> authorize
				.anyRequest().authenticated()
			)
			.oauth2Login(withDefaults())
			.logout(logout -> logout
				.logoutSuccessHandler(oidcLogoutSuccessHandler())
			);
	}

	private LogoutSuccessHandler oidcLogoutSuccessHandler() {
		OidcClientInitiatedLogoutSuccessHandler oidcLogoutSuccessHandler =
				new OidcClientInitiatedLogoutSuccessHandler(this.clientRegistrationRepository);

		// Sets the location that the End-User's User Agent will be redirected to
		// after the logout has been performed at the Provider
		oidcLogoutSuccessHandler.setPostLogoutRedirectUri("{baseUrl}");

		return oidcLogoutSuccessHandler;
	}
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@EnableWebSecurity
class OAuth2LoginSecurityConfig : WebSecurityConfigurerAdapter() {
    @Autowired
    private lateinit var clientRegistrationRepository: ClientRegistrationRepository

    override fun configure(http: HttpSecurity) {
        http {
            authorizeRequests {
                authorize(anyRequest, authenticated)
            }
            oauth2Login { }
            logout {
                logoutSuccessHandler = oidcLogoutSuccessHandler()
            }
        }
    }

    private fun oidcLogoutSuccessHandler(): LogoutSuccessHandler {
        val oidcLogoutSuccessHandler = OidcClientInitiatedLogoutSuccessHandler(clientRegistrationRepository)

        // Sets the location that the End-User's User Agent will be redirected to
        // after the logout has been performed at the Provider
        oidcLogoutSuccessHandler.setPostLogoutRedirectUri("{baseUrl}")
        return oidcLogoutSuccessHandler
    }
}
----
====

[NOTE]
====
`OidcClientInitiatedLogoutSuccessHandler` supports the `+{baseUrl}+` placeholder.
If used, the application's base URL, such as `https://app.example.org`, replaces it at request time.
====