Chapter 2. Using OpenID Connect to secure applications and services

The most important endpoint to understand is the well-known configuration endpoint. It lists endpoints and other configuration options relevant to the OpenID Connect implementation in Red Hat build of Keycloak. The endpoint is:

/realms/{realm-name}/.well-known/openid-configuration

To obtain the full URL, add the base URL for Red Hat build of Keycloak and replace {realm-name} with the name of your realm. For example:

http://localhost:8080/realms/master/.well-known/openid-configuration

Some RP libraries retrieve all required endpoints from this endpoint, but for others you might need to list the endpoints individually.

/realms/{realm-name}/protocol/openid-connect/auth

/realms/{realm-name}/protocol/openid-connect/token

/realms/{realm-name}/protocol/openid-connect/userinfo

/realms/{realm-name}/protocol/openid-connect/logout

/realms/{realm-name}/protocol/openid-connect/certs

/realms/{realm-name}/protocol/openid-connect/token/introspect

/realms/{realm-name}/clients-registrations/openid-connect

/realms/{realm-name}/protocol/openid-connect/revoke

/realms/{realm-name}/protocol/openid-connect/auth/device

/realms/{realm-name}/protocol/openid-connect/ext/ciba/auth

The Authorization Code flow redirects the user agent to Red Hat build of Keycloak. Once the user has successfully authenticated with Red Hat build of Keycloak, an Authorization Code is created and the user agent is redirected back to the application. The application then uses the authorization code along with its credentials to obtain an Access Token, Refresh Token and ID Token from Red Hat build of Keycloak.

The flow is targeted towards web applications, but is also recommended for native applications, including mobile applications, where it is possible to embed a user agent.

For more details refer to the Authorization Code Flow in the OpenID Connect specification.

The Implicit flow works similarly to the Authorization Code flow, but instead of returning an Authorization Code, the Access Token and ID Token is returned. This approach reduces the need for the extra invocation to exchange the Authorization Code for an Access Token. However, it does not include a Refresh Token. This results in the need to permit Access Tokens with a long expiration; however, that approach is not practical because it is very hard to invalidate these tokens. Alternatively, you can require a new redirect to obtain a new Access Token once the initial Access Token has expired. The Implicit flow is useful if the application only wants to authenticate the user and deals with logout itself.

You can instead use a Hybrid flow where both the Access Token and an Authorization Code are returned.

One thing to note is that both the Implicit flow and Hybrid flow have potential security risks as the Access Token may be leaked through web server logs and browser history. You can somewhat mitigate this problem by using short expiration for Access Tokens.

For more details, see the Implicit Flow in the OpenID Connect specification.

Per current OAuth 2.0 Security Best Current Practice, this flow should not be used. This flow is removed from the future OAuth 2.1 specification.

Resource Owner Password Credentials, referred to as Direct Grant in Red Hat build of Keycloak, allows exchanging user credentials for tokens. Per current OAuth 2.0 Security Best Practices, this flow should not be used, preferring alternative methods such as Section 2.2.5, “Device Authorization Grant” or Section 2.2.1, “Authorization code”.

The limitations of using this flow include:

Security concerns with this flow include:

For a client to be permitted to use the Resource Owner Password Credentials grant, the client has to have the Direct Access Grants Enabled option enabled.

This flow is not included in OpenID Connect, but is a part of the OAuth 2.0 specification. It is removed from the future OAuth 2.1 specification.

For more details, see the Resource Owner Password Credentials Grant chapter in the OAuth 2.0 specification.

curl \
  -d "client_id=myclient" \
  -d "client_secret=40cc097b-2a57-4c17-b36a-8fdf3fc2d578" \
  -d "username=user" \
  -d "password=password" \
  -d "grant_type=password" \
  "http://localhost:8080/realms/master/protocol/openid-connect/token"

Client Credentials are used when clients (applications and services) want to obtain access on behalf of themselves rather than on behalf of a user. For example, these credentials can be useful for background services that apply changes to the system in general rather than for a specific user.

Red Hat build of Keycloak provides support for clients to authenticate either with a secret or with public/private keys.

This flow is not included in OpenID Connect, but is a part of the OAuth 2.0 specification.

For more details, see the Client Credentials Grant chapter in the OAuth 2.0 specification.

Device Authorization Grant is used by clients running on internet-connected devices that have limited input capabilities or lack a suitable browser.

For more details, see the OAuth 2.0 Device Authorization Grant specification.

Client Initiated Backchannel Authentication Grant is used by clients who want to initiate the authentication flow by communicating with the OpenID Provider directly without redirect through the user’s browser like OAuth 2.0’s authorization code grant.

The client requests from Red Hat build of Keycloak an auth_req_id that identifies the authentication request made by the client. Red Hat build of Keycloak creates the auth_req_id.

After receiving this auth_req_id, this client repeatedly needs to poll Red Hat build of Keycloak to obtain an Access Token, Refresh Token, and ID Token from Red Hat build of Keycloak in return for the auth_req_id until the user is authenticated.

In case that client uses ping mode, it does not need to repeatedly poll the token endpoint, but it can wait for the notification sent by Red Hat build of Keycloak to the specified Client Notification Endpoint. The Client Notification Endpoint can be configured in the Red Hat build of Keycloak Admin Console. The details of the contract for Client Notification Endpoint are described in the CIBA specification.

For more details, see OpenID Connect Client Initiated Backchannel Authentication Flow specification.

Also refer to other places of Red Hat build of Keycloak documentation such as Backchannel Authentication Endpoint of this guide and Client Initiated Backchannel Authentication Grant section of Server Administration Guide. For the details about FAPI CIBA compliance, see the FAPI section of this guide.

Red Hat build of Keycloak does not include any adapters for Red Hat JBoss Enterprise Application Platform. However, there are alternatives for existing applications deployed to Red Hat JBoss Enterprise Application Platform.

Red Hat build of Keycloak does not include any adapters for Spring Boot. However, there are alternatives for existing applications built with Spring Boot.

Spring Security provides comprehensive support for OAuth 2 and OpenID Connect. For more information, see the Spring Security documentation.

Alternatively, for Spring Boot 2.x the Spring Boot adapter from Red Hat Single Sign-On 7.6 can be used in combination with the Red Hat build of Keycloak server. For more information, see the Red Hat Single Sign-On documentation.

The adapter is distributed in several ways, but we recommend that you install the keycloak-js package from NPM:

npm install keycloak-js

Alternatively, the library can be retrieved directly from the Red Hat build of Keycloak server at /js/keycloak.js and is also distributed as a ZIP archive. We are however considering the inclusion of the adapter directly from the Keycloak server as deprecated, and this functionality might be removed in the future.

One important thing to consider about using client-side applications is that the client has to be a public client as there is no secure way to store client credentials in a client-side application. This consideration makes it very important to make sure the redirect URIs you have configured for the client are correct and as specific as possible.

To use the adapter, create a client for your application in the Red Hat build of Keycloak Admin Console. Make the client public by toggling Client authentication to Off on the Capability config page.

You also need to configure Valid Redirect URIs and Web Origins. Be as specific as possible as failing to do so may result in a security vulnerability.

The following example shows how to initialize the adapter. Make sure that you replace the options passed to the Keycloak constructor with those of the client you have configured.

import Keycloak from 'keycloak-js';

const keycloak = new Keycloak({
    url: 'http://keycloak-server${kc_base_path}',
    realm: 'myrealm',
    clientId: 'myapp'
});

try {
    const authenticated = await keycloak.init();
    console.log(`User is ${authenticated ? 'authenticated' : 'not authenticated'}`);
} catch (error) {
    console.error('Failed to initialize adapter:', error);
}

To authenticate, you call the login function. Two options exist to make the adapter automatically authenticate. You can pass login-required or check-sso to the init() function.

You can configure a silent check-sso option. With this feature enabled, your browser will not perform a full redirect to the Red Hat build of Keycloak server and back to your application, but this action will be performed in a hidden iframe. Therefore, your application resources are only loaded and parsed once by the browser, namely when the application is initialized and not again after the redirect back from Red Hat build of Keycloak to your application. This approach is particularly useful in case of SPAs (Single Page Applications).

To enable the silent check-sso, you provide a silentCheckSsoRedirectUri attribute in the init method. Make sure this URI is a valid endpoint in the application; it must be configured as a valid redirect for the client in the Red Hat build of Keycloak Admin Console:

keycloak.init({
    onLoad: 'check-sso',
    silentCheckSsoRedirectUri: `${location.origin}/silent-check-sso.html`
});

The page at the silent check-sso redirect uri is loaded in the iframe after successfully checking your authentication state and retrieving the tokens from the Red Hat build of Keycloak server. It has no other task than sending the received tokens to the main application and should only look like this:

<!doctype html>
<html>
<body>
    <script>
        parent.postMessage(location.href, location.origin);
    </script>
</body>
</html>

Remember that this page must be served by your application at the specified location in silentCheckSsoRedirectUri and is not part of the adapter.

To enable login-required set onLoad to login-required and pass to the init method:

keycloak.init({
    onLoad: 'login-required'
});

After the user is authenticated the application can make requests to RESTful services secured by Red Hat build of Keycloak by including the bearer token in the Authorization header. For example:

async function fetchUsers() {
    const response = await fetch('/api/users', {
        headers: {
            accept: 'application/json',
            authorization: `Bearer ${keycloak.token}`
        }
    });

    return response.json();
}

One thing to keep in mind is that the access token by default has a short life expiration so you may need to refresh the access token prior to sending the request. You refresh this token by calling the updateToken() method. This method returns a Promise, which makes it easy to invoke the service only if the token was successfully refreshed and displays an error to the user if it was not refreshed. For example:

try {
    await keycloak.updateToken(30);
} catch (error) {
    console.error('Failed to refresh token:', error);
}

const users = await fetchUsers();

By default, the adapter creates a hidden iframe that is used to detect if a Single-Sign Out has occurred. This iframe does not require any network traffic. Instead the status is retrieved by looking at a special status cookie. This feature can be disabled by setting checkLoginIframe: false in the options passed to the init() method.

You should not rely on looking at this cookie directly. Its format can change and it’s also associated with the URL of the Red Hat build of Keycloak server, not your application.

By default, the adapter uses the Authorization Code flow.

With this flow, the Red Hat build of Keycloak server returns an authorization code, not an authentication token, to the application. The JavaScript adapter exchanges the code for an access token and a refresh token after the browser is redirected back to the application.

Red Hat build of Keycloak also supports the Implicit flow where an access token is sent immediately after successful authentication with Red Hat build of Keycloak. This flow may have better performance than the standard flow because no additional request exists to exchange the code for tokens, but it has implications when the access token expires.

However, sending the access token in the URL fragment can be a security vulnerability. For example the token could be leaked through web server logs and or browser history.

To enable implicit flow, you enable the Implicit Flow Enabled flag for the client in the Red Hat build of Keycloak Admin Console. You also pass the parameter flow with the value implicit to init method:

keycloak.init({
    flow: 'implicit'
})

Note that only an access token is provided and no refresh token exists. This situation means that once the access token has expired, the application has to redirect to Red Hat build of Keycloak again to obtain a new access token.

Red Hat build of Keycloak also supports the Hybrid flow.

This flow requires the client to have both the Standard Flow and Implicit Flow enabled in the Admin Console. The Red Hat build of Keycloak server then sends both the code and tokens to your application. The access token can be used immediately while the code can be exchanged for access and refresh tokens. Similar to the implicit flow, the hybrid flow is good for performance because the access token is available immediately. But, the token is still sent in the URL, and the security vulnerability mentioned earlier may still apply.

One advantage in the Hybrid flow is that the refresh token is made available to the application.

For the Hybrid flow, you need to pass the parameter flow with value hybrid to the init method:

keycloak.init({
    flow: 'hybrid'
});

Red Hat build of Keycloak supports hybrid mobile apps developed with Apache Cordova. The adapter has two modes for this: cordova and cordova-native:

The default is cordova, which the adapter automatically selects if no adapter type has been explicitly configured and window.cordova is present. When logging in, it opens an InApp Browser that lets the user interact with Red Hat build of Keycloak and afterwards returns to the app by redirecting to http://localhost. Because of this behavior, you whitelist this URL as a valid redirect-uri in the client configuration section of the Admin Console.

While this mode is easy to set up, it also has some disadvantages:

The alternative mode is`cordova-native`, which takes a different approach. It opens the login page using the system’s browser. After the user has authenticated, the browser redirects back into the application using a special URL. From there, the Red Hat build of Keycloak adapter can finish the login by reading the code or token from the URL.

You can activate the native mode by passing the adapter type cordova-native to the init() method:

keycloak.init({
    adapter: 'cordova-native'
});

This adapter requires two additional plugins:

The technical details for linking to an app differ on each platform and special setup is needed. Please refer to the Android and iOS sections of the deeplinks plugin documentation for further instructions.

Different kinds of links exist for opening apps: * custom schemes, such as myapp://login or android-app://com.example.myapp/https/example.com/login * Universal Links (iOS)) / Deep Links (Android). While the former are easier to set up and tend to work more reliably, the latter offer extra security because they are unique and only the owner of a domain can register them. Custom-URLs are deprecated on iOS. For best reliability, we recommend that you use universal links combined with a fallback site that uses a custom-url link.

Furthermore, we recommend the following steps to improve compatibility with the adapter:

<preference name="AndroidLaunchMode" value="singleTask" />

In some situations, you may need to run the adapter in environments that are not supported by default, such as Capacitor. To use the JavasScript client in these environments, you can pass a custom adapter. For example, a third-party library could provide such an adapter to make it possible to reliably run the adapter:

import Keycloak from 'keycloak-js';
import KeycloakCapacitorAdapter from 'keycloak-capacitor-adapter';

const keycloak = new Keycloak();

keycloak.init({
    adapter: KeycloakCapacitorAdapter,
});

This specific package does not exist, but it gives a pretty good example of how such an adapter could be passed into the client.

It’s also possible to make your own adapter, to do so you will have to implement the methods described in the KeycloakAdapter interface. For example the following TypeScript code ensures that all the methods are properly implemented:

import Keycloak, { KeycloakAdapter } from 'keycloak-js';

// Implement the 'KeycloakAdapter' interface so that all required methods are guaranteed to be present.
const MyCustomAdapter: KeycloakAdapter = {
    login(options) {
        // Write your own implementation here.
    }

    // The other methods go here...
};

const keycloak = new Keycloak();

keycloak.init({
    adapter: MyCustomAdapter,
});

Naturally you can also do this without TypeScript by omitting the type information, but ensuring implementing the interface properly will then be left entirely up to you.

In the latest versions of some browsers, various cookies policies are applied to prevent tracking of the users by third parties, such as SameSite in Chrome or completely blocked third-party cookies. Those policies are likely to become more restrictive and adopted by other browsers over time. Eventually cookies in third-party contexts may become completely unsupported and blocked by the browsers. As a result, the affected adapter features might ultimately be deprecated.

The adapter relies on third-party cookies for Session Status iframe, silent check-sso and partially also for regular (non-silent) check-sso. Those features have limited functionality or are completely disabled based on how restrictive the browser is regarding cookies. The adapter tries to detect this setting and reacts accordingly.

Assuming you have already installed Node.js, create a folder for your application:

mkdir myapp && cd myapp

Use npm init command to create a package.json for your application. Now add the Red Hat build of Keycloak connect adapter in the dependencies list:

    "dependencies": {
        "keycloak-connect": "file:keycloak-connect-24.0.0+redhat-00001.tgz"
    }

In the root directory of your project create a file called server.js and add the following code:

    const session = require('express-session');
    const Keycloak = require('keycloak-connect');

    const memoryStore = new session.MemoryStore();
    const keycloak = new Keycloak({ store: memoryStore });

Install the express-session dependency:

    npm install express-session

To start the server.js script, add the following command in the 'scripts' section of the package.json:

    "scripts": {
        "test": "echo \"Error: no test specified\" && exit 1",
        "start": "node server.js"
    },

Now we have the ability to run our server with following command:

    npm run start

By default, this will locate a file named keycloak.json alongside the main executable of your application, in our case on the root folder, to initialize Red Hat build of Keycloak specific settings such as public key, realm name, various URLs.

In that case a Red Hat build of Keycloak deployment is necessary to access Red Hat build of Keycloak admin console.

Please visit links on how to deploy a Red Hat build of Keycloak admin console with Podman or Docker

Now we are ready to obtain the keycloak.json file by visiting the Red Hat build of Keycloak Admin Console clients (left sidebar) choose your client Installation Format Option Keycloak OIDC JSON Download

Paste the downloaded file on the root folder of our project.

Instantiation with this method results in all the reasonable defaults being used. As alternative, it’s also possible to provide a configuration object, rather than the keycloak.json file:

    const kcConfig = {
        clientId: 'myclient',
        bearerOnly: true,
        serverUrl: 'http://localhost:8080',
        realm: 'myrealm',
        realmPublicKey: 'MIIBIjANB...'
    };

    const keycloak = new Keycloak({ store: memoryStore }, kcConfig);

Applications can also redirect users to their preferred identity provider by using:

    const keycloak = new Keycloak({ store: memoryStore, idpHint: myIdP }, kcConfig);

    const session = require('express-session');
    const memoryStore = new session.MemoryStore();

    // Configure session
    app.use(
      session({
        secret: 'mySecret',
        resave: false,
        saveUninitialized: true,
        store: memoryStore,
      })
    );

    const keycloak = new Keycloak({ store: memoryStore });

    const keycloak = new Keycloak({ scope: 'offline_access' });

Once instantiated, install the middleware into your connect-capable app:

In order to do so, first we have to install Express:

    npm install express

then require Express in our project as outlined below:

    const express = require('express');
    const app = express();

and configure Keycloak middleware in Express, by adding at the code below:

    app.use( keycloak.middleware() );

Last but not least, let’s set up our server to listen for HTTP requests on port 3000 by adding the following code to main.js:

    app.listen(3000, function () {
        console.log('App listening on port 3000');
    });

If the application is running behind a proxy that terminates an SSL connection Express must be configured per the express behind proxies guide. Using an incorrect proxy configuration can result in invalid redirect URIs being generated.

Example configuration:

    const app = express();

    app.set( 'trust proxy', true );

    app.use( keycloak.middleware() );

    app.get( '/complain', keycloak.protect(), complaintHandler );

    app.get( '/special', keycloak.protect('special'), specialHandler );

To secure a resource with an application role for a different app:

    app.get( '/extra-special', keycloak.protect('other-app:special'), extraSpecialHandler );

To secure a resource with a realm role:

    app.get( '/admin', keycloak.protect( 'realm:admin' ), adminHandler );

    app.get('/apis/me', keycloak.enforcer('user:profile'), userProfileHandler);

The keycloak-enforcer method operates in two modes, depending on the value of the response_mode configuration option.

    app.get('/apis/me', keycloak.enforcer('user:profile', {response_mode: 'token'}), userProfileHandler);

If response_mode is set to token, permissions are obtained from the server on behalf of the subject represented by the bearer token that was sent to your application. In this case, a new access token is issued by Keycloak with the permissions granted by the server. If the server did not respond with a token with the expected permissions, the request is denied. When using this mode, you should be able to obtain the token from the request as follows:

    app.get('/apis/me', keycloak.enforcer('user:profile', {response_mode: 'token'}), function (req, res) {
        const token = req.kauth.grant.access_token.content;
        const permissions = token.authorization ? token.authorization.permissions : undefined;

        // show user profile
    });

Prefer this mode when your application is using sessions and you want to cache previous decisions from the server, as well automatically handle refresh tokens. This mode is especially useful for applications acting as a client and resource server.

If response_mode is set to permissions (default mode), the server only returns the list of granted permissions, without issuing a new access token. In addition to not issuing a new token, this method exposes the permissions granted by the server through the request as follows:

    app.get('/apis/me', keycloak.enforcer('user:profile', {response_mode: 'permissions'}), function (req, res) {
        const permissions = req.permissions;

        // show user profile
    });

Regardless of the response_mode in use, the keycloak.enforcer method will first try to check the permissions within the bearer token that was sent to your application. If the bearer token already carries the expected permissions, there is no need to interact with the server to obtain a decision. This is specially useful when your clients are capable of obtaining access tokens from the server with the expected permissions before accessing a protected resource, so they can use some capabilities provided by Keycloak Authorization Services such as incremental authorization and avoid additional requests to the server when keycloak.enforcer is enforcing access to the resource.

By default, the policy enforcer will use the client_id defined to the application (for instance, via keycloak.json) to reference a client in Keycloak that supports Keycloak Authorization Services. In this case, the client can not be public given that it is actually a resource server.

If your application is acting as both a public client(frontend) and resource server(backend), you can use the following configuration to reference a different client in Keycloak with the policies that you want to enforce:

      keycloak.enforcer('user:profile', {resource_server_id: 'my-apiserver'})

It is recommended to use distinct clients in Keycloak to represent your frontend and backend.

If the application you are protecting is enabled with Keycloak authorization services and you have defined client credentials in keycloak.json, you can push additional claims to the server and make them available to your policies in order to make decisions. For that, you can define a claims configuration option which expects a function that returns a JSON with the claims you want to push:

      app.get('/protected/resource', keycloak.enforcer(['resource:view', 'resource:write'], {
          claims: function(request) {
            return {
              "http.uri": ["/protected/resource"],
              "user.agent": // get user agent  from request
            }
          }
        }), function (req, res) {
          // access granted

For more details about how to configure Keycloak to protected your application resources, please take a look at the Authorization Services Guide.

    function protectBySection(token, request) {
      return token.hasRole( request.params.section );
    }

    app.get( '/:section/:page', keycloak.protect( protectBySection ), sectionHandler );

Advanced Login Configuration:

By default, all unauthorized requests will be redirected to the Red Hat build of Keycloak login page unless your client is bearer-only. However, a confidential or public client may host both browsable and API endpoints. To prevent redirects on unauthenticated API requests and instead return an HTTP 401, you can override the redirectToLogin function.

For example, this override checks if the URL contains /api/ and disables login redirects:

    Keycloak.prototype.redirectToLogin = function(req) {
    const apiReqMatcher = /\/api\//i;
    return !apiReqMatcher.test(req.originalUrl || req.url);
    };

    app.use( keycloak.middleware( { logout: '/logoff' } ));

When the user-triggered logout is invoked a query parameter redirect_url can be passed:

https://example.com/logoff?redirect_url=https%3A%2F%2Fexample.com%3A3000%2Flogged%2Fout

This parameter is then used as the redirect url of the OIDC logout endpoint and the user will be redirected to https://example.com/logged/out.

    app.use( keycloak.middleware( { admin: '/callbacks' } );

A complete example using the Node.js adapter usage can be found in Keycloak quickstarts for Node.js

To make sure that your clients are FAPI compliant, you can configure Client Policies in your realm as described in the Server Administration Guide and link them to the global client profiles for FAPI support, which are automatically available in each realm. You can use either fapi-1-baseline or fapi-1-advanced profile based on which FAPI profile you need your clients to conform with. You can use also profiles fapi-2-security-profile or fapi-2-message-signing for the compliance with FAPI 2 Draft specifications.

In case you want to use Pushed Authorization Request (PAR), it is recommended that your client use both the fapi-1-baseline profile and fapi-1-advanced for PAR requests. Specifically, the fapi-1-baseline profile contains pkce-enforcer executor, which makes sure that client use PKCE with secured S256 algorithm. This is not required for FAPI Advanced clients unless they use PAR requests.

In case you want to use CIBA in a FAPI compliant way, make sure that your clients use both fapi-1-advanced and fapi-ciba client profiles. There is a need to use the fapi-1-advanced profile, or other client profile containing the requested executors, as the fapi-ciba profile contains just CIBA-specific executors. When enforcing the requirements of the FAPI CIBA specification, there is a need for more requirements, such as enforcement of confidential clients or certificate-bound access tokens.

Red Hat build of Keycloak is compliant with the Open Finance Brasil Financial-grade API Security Profile 1.0 Implementers Draft 3. This one is stricter in some requirements than the FAPI 1 Advanced specification and hence it may be needed to configure Client Policies in the more strict way to enforce some of the requirements. Especially:

Red Hat build of Keycloak is compliant with the Australia Consumer Data Right Security Profile.

If you want to apply the Australia CDR security profile, you need to use fapi-1-advanced profile because the Australia CDR security profile is based on FAPI 1.0 Advanced security profile. If your client also applies PAR, make sure that client applies RFC 7637 Proof Key for Code Exchange (PKCE) because the Australia CDR security profile requires that you apply PKCE when applying PAR. This can be achieved by using a client profile with the pkce-enforcer executor.

As confidential information is being exchanged, all interactions shall be encrypted with TLS (HTTPS). Moreover, there are some requirements in the FAPI specification for the cipher suites and TLS protocol versions used. To match these requirements, you can consider configure allowed ciphers. This configuration can be done by setting the https-protocols and https-cipher-suites options. Red Hat build of Keycloak uses TLSv1.3 by default and hence it is possibly not needed to change the default settings. However it may be needed to adjust ciphers if you need to fall back to lower TLS version for some reason. For more details, see Configuring TLS chapter.

To make sure that your clients are OAuth 2.1 compliant, you can configure Client Policies in your realm as described in the Server Administration Guide and link them to the global client profiles for OAuth 2.1 support, which are automatically available in each realm. You can use either oauth-2-1-for-confidential-client profile for confidential clients or oauth-2-1-for-public-client profile for public clients.

If you need to manually validate access tokens issued by Red Hat build of Keycloak, you can invoke the Introspection Endpoint. The downside to this approach is that you have to make a network invocation to the Red Hat build of Keycloak server. This can be slow and possibly overload the server if you have too many validation requests going on at the same time. Red Hat build of Keycloak issued access tokens are JSON Web Tokens (JWT) digitally signed and encoded using JSON Web Signature (JWS). Because they are encoded in this way, you can locally validate access tokens using the public key of the issuing realm. You can either hard code the realm’s public key in your validation code, or lookup and cache the public key using the certificate endpoint with the Key ID (KID) embedded within the JWS. Depending on what language you code in, many third party libraries exist and they can help you with JWS validation.

When using the redirect based flows, be sure to use valid redirect uris for your clients. The redirect uris should be as specific as possible. This especially applies to client-side (public clients) applications. Failing to do so could result in:

In production for web applications always use https for all redirect URIs. Do not allow redirects to http.

A few special redirect URIs also exist: