# 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:

Example 1. Advanced OAuth2 Login Configuration

Java

```
@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

```
@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 [Protocol Endpoints](https://tools.ietf.org/html/rfc6749#section-3) as follows:

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

* Authorization Endpoint: Used by the client to obtain authorization from the resource owner via user-agent redirection.

* Token Endpoint: Used by the client to exchange an authorization grant for an access token, typically with client authentication.

As well as one client endpoint:

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

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

Example 2. OAuth2 Login Configuration Options

Java

```
@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

```
@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 [ security namespace](../../appendix/namespace/http.html#nsa-oauth2-login):

Example 3. OAuth2 Login XML Configuration Options

```
<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:

* [OAuth 2.0 Login Page](#oauth2login-advanced-login-page)

* [Redirection Endpoint](#oauth2login-advanced-redirection-endpoint)

* [UserInfo Endpoint](#oauth2login-advanced-userinfo-endpoint)

* [ID Token Signature Verification](#oauth2login-advanced-idtoken-verify)

* [OpenID Connect 1.0 Logout](#oauth2login-advanced-oidc-logout)

## 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).

|   |In order for `DefaultLoginPageGeneratingFilter` to show links for configured OAuth Clients, the registered `ClientRegistrationRepository` needs to also implement `Iterable<ClientRegistration>`.<br/>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:

```
<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:

Example 4. OAuth2 Login Page Configuration

Java

```
@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

```
@EnableWebSecurity
class OAuth2LoginSecurityConfig : WebSecurityConfigurerAdapter() {

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

Xml

```
<http>
	<oauth2-login login-page="/login/oauth2"
				  ...
    />
</http>
```

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

|   |As noted earlier, configuring `oauth2Login().authorizationEndpoint().baseUri()` is optional.<br/>However, if you choose to customize it, ensure the link to each OAuth Client matches the `authorizationEndpoint().baseUri()`.<br/><br/>The following line shows an example:<br/><br/>```<br/><a href="/login/oauth2/authorization/google">Google</a><br/>```|
|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

## Redirection Endpoint

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

|   |OAuth 2.0 Login leverages the Authorization Code Grant.<br/>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 shown in the following example:

Example 5. Redirection Endpoint Configuration

Java

```
@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

```
@EnableWebSecurity
class OAuth2LoginSecurityConfig : WebSecurityConfigurerAdapter() {

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

Xml

```
<http>
	<oauth2-login login-processing-url="/login/oauth2/callback/*"
				  ...
    />
</http>
```

|   |You also need to ensure the `ClientRegistration.redirectUri` matches the custom Authorization Response `baseUri`.<br/><br/>The following listing shows an example:<br/><br/>Java<br/><br/>```<br/>return CommonOAuth2Provider.GOOGLE.getBuilder("google")<br/>	.clientId("google-client-id")<br/>	.clientSecret("google-client-secret")<br/>	.redirectUri("{baseUrl}/login/oauth2/callback/{registrationId}")<br/>	.build();<br/>```<br/><br/>Kotlin<br/><br/>```<br/>return CommonOAuth2Provider.GOOGLE.getBuilder("google")<br/>    .clientId("google-client-id")<br/>    .clientSecret("google-client-secret")<br/>    .redirectUri("{baseUrl}/login/oauth2/callback/{registrationId}")<br/>    .build()<br/>```|
|---| |

## UserInfo Endpoint

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

* [Mapping User Authorities](#oauth2login-advanced-map-authorities)

* [OAuth 2.0 UserService](#oauth2login-advanced-oauth2-user-service)

* [OpenID Connect 1.0 UserService](#oauth2login-advanced-oidc-user-service)

### Mapping User Authorities

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

|   |`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:

* [Using a GrantedAuthoritiesMapper](#oauth2login-advanced-map-authorities-grantedauthoritiesmapper)

* [Delegation-based strategy with OAuth2UserService](#oauth2login-advanced-map-authorities-oauth2userservice)

#### Using a GrantedAuthoritiesMapper

Provide an implementation of `GrantedAuthoritiesMapper` and configure it as shown in the following example:

Example 6. Granted Authorities Mapper Configuration

Java

```
@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

```
@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

```
<http>
	<oauth2-login user-authorities-mapper-ref="userAuthoritiesMapper"
				  ...
    />
</http>
```

Alternatively, you may register a `GrantedAuthoritiesMapper` `@Bean` to have it automatically applied to the configuration, as shown in the following example:

Example 7. Granted Authorities Mapper Bean Configuration

Java

```
@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

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

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

Kotlin

```
@EnableWebSecurity
class OAuth2LoginSecurityConfig : WebSecurityConfigurerAdapter() {

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

    @Bean
    fun userAuthoritiesMapper(): GrantedAuthoritiesMapper {
        ...
    }
}
```

#### Delegation-based strategy with OAuth2UserService

This strategy is advanced compared to using a `GrantedAuthoritiesMapper`, however, it’s 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 the 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:

Example 8. OAuth2UserService Configuration

Java

```
@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

```
@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

```
<http>
	<oauth2-login oidc-user-service-ref="oidcUserService"
				  ...
    />
</http>
```

### OAuth 2.0 UserService

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

|   |`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` 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 will need to provide `DefaultOAuth2UserService.setRestOperations()` with a custom configured `RestOperations`.
The default `RestOperations` is configured as follows:

```
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’ll need to configure it as shown in the following example:

Java

```
@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

```
@EnableWebSecurity
class OAuth2LoginSecurityConfig : WebSecurityConfigurerAdapter() {

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

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

### 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 and/or the post-handling of the UserInfo Response, you will 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’ll need to configure it as shown in the following example:

Java

```
@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

```
@EnableWebSecurity
class OAuth2LoginSecurityConfig : WebSecurityConfigurerAdapter() {

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

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

## ID Token Signature Verification

OpenID Connect 1.0 Authentication introduces the [ID Token](https://openid.net/specs/openid-connect-core-1_0.html#IDToken), 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 [JSON Web Token](https://tools.ietf.org/html/rfc7519) (JWT) and MUST be signed using [JSON Web Signature](https://tools.ietf.org/html/rfc7515) (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, a resolver may be configured 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, eg. `SignatureAlgorithm.RS256` or `MacAlgorithm.HS256`

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

Java

```
@Bean
public JwtDecoderFactory<ClientRegistration> idTokenDecoderFactory() {
	OidcIdTokenDecoderFactory idTokenDecoderFactory = new OidcIdTokenDecoderFactory();
	idTokenDecoderFactory.setJwsAlgorithmResolver(clientRegistration -> MacAlgorithm.HS256);
	return idTokenDecoderFactory;
}
```

Kotlin

```
@Bean
fun idTokenDecoderFactory(): JwtDecoderFactory<ClientRegistration?> {
    val idTokenDecoderFactory = OidcIdTokenDecoderFactory()
    idTokenDecoderFactory.setJwsAlgorithmResolver { MacAlgorithm.HS256 }
    return idTokenDecoderFactory
}
```

|   |For MAC based algorithms such as `HS256`, `HS384` or `HS512`, the `client-secret` corresponding to the `client-id` is used as the symmetric key for signature verification.|
|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   |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.|
|---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

## OpenID Connect 1.0 Logout

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

If the OpenID Provider supports both Session Management and [Discovery](https://openid.net/specs/openid-connect-discovery-1_0.html), the client may obtain the `end_session_endpoint` `URL` from the OpenID Provider’s [Discovery Metadata](https://openid.net/specs/openid-connect-session-1_0.html#OPMetadata).
This can be achieved by configuring the `ClientRegistration` with the `issuer-uri`, as in the following example:

```
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
```

…​and the `OidcClientInitiatedLogoutSuccessHandler`, which implements RP-Initiated Logout, may be configured as follows:

Java

```
@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

```
@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
    }
}
```

|   |`OidcClientInitiatedLogoutSuccessHandler` supports the `{baseUrl}` placeholder.<br/>If used, the application’s base URL, like `[https://app.example.org](https://app.example.org)`, will replace it at request time.|
|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

[Core Configuration](core.html)[OAuth2 Client](../client/index.html)