For our new friends:

Logto is an Auth0 alternative designed for modern apps and SaaS products. It offers both Cloud and Open-source services to help you quickly launch your identity and management (IAM) system. Enjoy authentication, authorization, and multi-tenant management all in one.

We recommend starting with a free development tenant on Logto Cloud. This allows you to explore all the features easily.

In this article, we will go through the steps to quickly build the Microsoft Entra ID SAML enterprise SSO sign-in experience (user authentication) with Flutter and Logto.

Prerequisites

• A running Logto instance. Check out the introduction page to get started.
• Basic knowledge of Flutter.
• A usable Microsoft Entra ID SAML enterprise SSO account.

Create an application in Logto

Logto is based on OpenID Connect (OIDC) authentication and OAuth 2.0 authorization. It supports federated identity management across multiple applications, commonly called Single Sign-On (SSO).

To create your Native app application, simply follow these steps:

1. Open the Logto Console. In the "Get started" section, click the "View all" link to open the application frameworks list. Alternatively, you can navigate to Logto Console > Applications, and click the "Create application" button.
2. In the opening modal, click the "Native app" section or filter all the available "Native app" frameworks using the quick filter checkboxes on the left. Click the "Flutter" framework card to start creating your application.
3. Enter the application name, e.g., "Bookstore," and click "Create application".

🎉 Ta-da! You just created your first application in Logto. You'll see a congrats page which includes a detailed integration guide. Follow the guide to see what the experience will be in your application.

Integrate Flutter SDK

tip:

• The SDK package is available on pub.dev and Logto GitHub repository.
• The sample project is built using Flutter material. You can find it on pub.dev.
• This SDK is compatible with Flutter applications on iOS, Android, and Web platforms. Compatibility with other platforms has not been tested.

Installation

pub.dev

You can install the logto_dart_sdk package directly using the pub package manager. Run the following command under your project root:

flutter pub add logto_dart_sdk

Or add the following to your pubspec.yaml file:

dependencies:
  logto_dart_sdk: ^3.0.0

Then run:

flutter pub get

GitHub

If you prefer to fork your own version of the SDK, you can clone the repository directly from GitHub.

git clone https://github.com/logto-io/dart

Dependency and configurations

SDK version compatibility

Logto SDK version	Dart SDK version	Dart 3.0 compatible
< 2.0.0	>= 2.17.6 < 3.0.0	false
>= 2.0.0 < 3.0.0	>= 3.0.0	true
>= 3.0.0	>= 3.6.0	true

flutter_secure_storage set up

Under the hood, this SDK uses flutter_secure_storage to implement the cross-platform persistent secure token storage.

• Keychain is used for iOS
• AES encryption is used for Android.

Config Android version

Set the android:minSdkVersion to >= 18 in your project's android/app/build.gradle file.

build.gradle

  android {
      ...

      defaultConfig {
          ...
          minSdkVersion 18
          ...
      }
  }

Disable auto backup on Android

By default Android backups data on Google Drive. It can cause exception java.security.InvalidKeyException:Failed to unwrap key. To avoid this,

1. To disable auto backup, go to your app manifest file and set the android:allowBackup and android:fullBackupContent attributes to false.

   AndroidManifest.xml

   <manifest ... >
       ...
       <application
         android:allowBackup="false"
         android:fullBackupContent="false"
         ...
       >
           ...
       </application>
   </manifest>
   

2. Exclude sharedprefs from FlutterSecureStorage.

   If you need to keep the android:fullBackupContent for your app rather than disabling it, you can exclude the sharedprefs directory from the backup. See more details in the Android documentation.

   In your AndroidManifest.xml file, add the android:fullBackupContent attribute to the <application> element, as shown in the following example. This attribute points to an XML file that contains backup rules.

   AndroidManifest.xml

   <application ...
     android:fullBackupContent="@xml/backup_rules">
   </application>

   Create an XML file called @xml/backup_rules in the res/xml/ directory. In this file, add rules with the <include> and <exclude> elements. The following sample backs up all shared preferences except device.xml:

   @xml/backup_rules

   <?xml version="1.0" encoding="utf-8"?>
   <full-backup-content>
     <exclude domain="sharedpref" path="FlutterSecureStorage"/>
   </full-backup-content>

Please check flutter_secure_storage for more details.

flutter_web_auth_2 set up

Behind the scenes, this SDK uses flutter_web_auth_2 to authenticate users with Logto. This package provides a simple way to authenticate users with Logto using the system webview or browser.

This plugin uses ASWebAuthenticationSession on iOS 12+ and macOS 10.15+, SFAuthenticationSession on iOS 11, Chrome Custom Tabs on Android and opens a new window on Web.

• iOS: No additional setup required

• Android: Register the callback url on Android

  In order to capture the callback url from Logto's sign-in web page, you will need to register your sign-in redirectUri to your AndroidManifest.xml file.

  AndroidManifest.xml

    <manifest>
      <application>
          <activity
            android:name="com.linusu.flutter_web_auth_2.CallbackActivity"
            android:exported="true">
            <intent-filter android:label="flutter_web_auth_2">
            <action android:name="android.intent.action.VIEW" />
            <category android:name="android.intent.category.DEFAULT" />
            <category android:name="android.intent.category.BROWSABLE" />
            <data android:scheme="YOUR_CALLBACK_URL_SCHEME_HERE" />
            </intent-filter>
          </activity>
      </application>
    </manifest>

• Web browser: Create an endpoint to handle the callback URL

  If you are using the web platform, you need to create an endpoint to handle the callback URL and send it back to the application using the postMessage API.

  callback.html

  <!doctype html>
  <title>Authentication complete</title>
  <p>Authentication is complete. If this does not happen automatically, please close the window.</p>
  <script>
    function postAuthenticationMessage() {
      const message = {
        'flutter-web-auth-2': window.location.href,
      };
  
      if (window.opener) {
        window.opener.postMessage(message, window.location.origin);
        window.close();
      } else if (window.parent && window.parent !== window) {
        window.parent.postMessage(message, window.location.origin);
      } else {
        localStorage.setItem('flutter-web-auth-2', window.location.href);
        window.close();
      }
    }
  
    postAuthenticationMessage();
  </script>

Please check the setup guide in the flutter_web_auth_2 package for more details.

Integration

Init LogtoClient

Import the logto_dart_sdk package and initialize the LogtoClient instance at the root of your application.

lib/main.dart

import 'package:logto_dart_sdk/logto_dart_sdk.dart';
import 'package:http/http.dart' as http;

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: 'Flutter Demo',
      home: MyHomePage(title: 'Logto Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);
  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  late LogtoClient logtoClient;

  void render() {
    // state change
  }

  // LogtoConfig
  final logtoConfig = const LogtoConfig(
    endpoint: "<your-logto-endpoint>",
    appId: "<your-app-id>"
  );

  void _init() {
    logtoClient = LogtoClient(
      config: logtoConfig,
      httpClient: http.Client(), // Optional http client
    );
    render();
  }

  @override
  void initState() {
    super.initState();
    _init();
  }

  // ...
}

Implement sign-in

Before we dive into the details, here's a quick overview of the end-user experience. The sign-in process can be simplified as follows:

1. Your app invokes the sign-in method.
2. The user is redirected to the Logto sign-in page. For native apps, the system browser is opened.
3. The user signs in and is redirected back to your app (configured as the redirect URI).

Regarding redirect-based sign-in

1. This authentication process follows the OpenID Connect (OIDC) protocol, and Logto enforces strict security measures to protect user sign-in.
2. If you have multiple apps, you can use the same identity provider (Logto). Once the user signs in to one app, Logto will automatically complete the sign-in process when the user accesses another app.

To learn more about the rationale and benefits of redirect-based sign-in, see Logto sign-in experience explained.

---

Before starting, you need to add a redirect URI in the Admin Console for your application.

Let's switch to the Application details page of Logto Console. Add a Redirect URI io.logto://callback and click "Save changes".

• For iOS, the redirect URI scheme does not really matter since the ASWebAuthenticationSession class will listen to the redirect URI regardless of if it's registered.
• For Android, the redirect URI scheme must be registered in the AndroidManifest.xml file.

After the redirect URI is configured, we add a sign-in button to your page, which will call logtoClient.signIn API to invoke the Logto sign-in flow:

lib/main.dart

class _MyHomePageState extends State<MyHomePage> {
  // ...
  final redirectUri = 'io.logto://callback';

  @override
  Widget build(BuildContext context) {
    // ...

    Widget signInButton = TextButton(
      onPressed: () async {
        await logtoClient.signIn(redirectUri);
        render();
      },
      child: const Text('Sign In'),
    );

    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            SelectableText('My Demo App'),
            signInButton,
          ],
        ),
      ),
    );
  }
}

Implement sign-out

Let's switch to the Application details page of Logto Console. Add a Post Sign-out Redirect URI io.logto://callback and click "Save changes".

Post Sign-outRedirect URI is an OAuth 2.0 concept which implies the location should redirect after signing out.

Now let's add a sign-out button on the main page so users can sign out from your application.

lib/main.dart

class _MyHomePageState extends State<MyHomePage> {
  // ...

  final postSignOutRedirectUri = 'io.logto//home';

  @override
  Widget build(BuildContext context) {
    // ...

    Widget signOutButton = TextButton(
      onPressed: () async {
        await logtoClient.signOut(postSignOutRedirectUri);
        render();
      },
      child: const Text('Sign Out'),
    );

    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            SelectableText('My Demo App'),
            signInButton,
            signOutButton,
          ],
        ),
      ),
    );
  }
}

Handle authentication status

Logto SDK provides an asynchronous method to check the authentication status. The method is logtoClient.isAuthenticated. The method returns a boolean value, true if the user is authenticated, otherwise false.

In the example we conditionally render the sign-in and sign-out buttons based on the authentication status. Now let's update the render method in our Widget to handle the state change:

lib/main.dart

class _MyHomePageState extends State<MyHomePage> {
  // ...
  bool? isAuthenticated = false;

  void render() {
    setState(() async {
      isAuthenticated = await logtoClient.isAuthenticated;
    });
  }

  @override
  Widget build(BuildContext context) {
    // ...

    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            SelectableText('My Demo App'),
            isAuthenticated == true ? signOutButton : signInButton,
          ],
        ),
      ),
    );
  }
}

Checkpoint: Test your application

Now, you can test your application:

1. Run your application, you will see the sign-in button.
2. Click the sign-in button, the SDK will init the sign-in process and redirect you to the Logto sign-in page.
3. After you signed in, you will be redirected back to your application and see the sign-out button.
4. Click the sign-out button to clear token storage and sign out.

Add Microsoft Entra ID SAML enterprise SSO connector

To simplify access management and gain enterprise-level safeguards for your big clients, connect with Flutter as a federated identity provider. The Logto enterprise SSO connector helps you establish this connection in minutes by allowing several parameter inputs.

To add an enterprise SSO connector, simply follow these steps:

1. Navigate to Logto console > Enterprise SSO.

2. Click "Add enterprise connector" button and choose your SSO provider type. Choose from prebuilt connectors for Microsoft Entra ID (Azure AD), Google Workspace, and Okta, or create a custom SSO connection using the standard OpenID Connect (OIDC) or SAML protocol.
3. Provide a unique name (e.g., SSO sign-in for Acme Company).

4. Configure the connection with your IdP in the "Connection" tab. Check the guides above for each connector types.

5. Customize the SSO experience and enterprise’s email domain in the "Experience" tab. Users sign in with the SSO-enabled email domain will be redirected to SSO authentication.

6. Save changes.

Set up Azure AD SSO application

Step 1: Create an Azure AD SSO application

Initiate the Azure AD SSO integration by creating an SSO application on the Azure AD side.

1. Go to the Azure portal and sign in as an administrator.
2. Select Microsoft Entra ID service.
3. Navigate to the Enterprise applications using the side menu. Click New application, and select Create your own application.

1. Enter the application name and select Integrate any other application you don't find in the gallery (Non-gallery).
2. Select Setup single sign-on > SAML.

1. Follow the instructions, as the first step, you will need to fill in the basic SAML configuration using the following information provided by Logto.

• Audience URI(SP Entity ID): It represents as a globally unique identifier for your Logto service, functioning as the EntityId for SP during authentication requests to the IdP. This identifier is pivotal for the secure exchange of SAML assertions and other authentication-related data between the IdP and Logto.
• ACS URL: The Assertion Consumer Service (ACS) URL is the location where the SAML assertion is sent with a POST request. This URL is used by the IdP to send the SAML assertion to Logto. It acts as a callback URL where Logto expects to receive and consume the SAML response containing the user's identity information.

Click Save to continue.

Step 2: Configure SAML SSO at Logto

To make the SAML SSO integration work, you will need to provide the IdP metadata back to Logto. Let's switch back to the Logto side, and navigate to the Connection tab of your Azure AD SSO connector.

Logto provides three different ways to configure the IdP metadata. The easiest way is by providing the metadata URL of the Azure AD SSO application.

Copy the App Federation Metadata Url from your Azure AD SSO application's SAML Certificates section and paste it into the Metadata URL field in Logto.

Logto will fetch the metadata from the URL and configure the SAML SSO integration automatically.

Step 3: Configure user attributes mapping

Logto provides a flexible way to map the user attributes returned from IdP to the user attributes in Logto. Logto will sync the following user attributes from IdP by default:

• id: The unique identifier of the user. Logto will read the nameID claim from the SAML response as the user SSO identity id.
• email: The email address of the user. Logto will read the email claim from the SAML response as the user primary email by default.
• name: The name of the user.

You may manage the user attributes mapping logic either on the Azure AD side or Logto side.

1. Map the AzureAD user attributes to Logto user attributes on Logto side.

   Visit the Attributes & Claims section of your Azure AD SSO application.

   Copy the following attribute names (with namespace prefix) and paste them into the corresponding fields in Logto.

   • http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress
   • http://schemas.xmlsoap.org/ws/2005/05/identity/claims/name (Recommendation: update this attribute value map to user.displayname for better user experience)a

1. Map the AzureAD user attributes to Logto user attributes at the AzureAD side.

   Visit the Attributes & Claims section of your Azure AD SSO application.

   Click on Edit, and update the Additional claims fields based on the Logto user attributes settings:

   • update the claim name value based on the Logto user attributes settings.
   • remove the namespace prefix.
   • click Save to continue.

   Should end up with the following settings:

You may also specify additional user attributes on the Azure AD side. Logto will keep a record of the original user attributes returned from IdP under the user's sso_identity field.

Step 4: Assign users to the Azure AD SSO application

Visit the Users and groups section of your Azure AD SSO application. Click on Add user/group to assign users to the Azure AD SSO application. Only users assigned to your Azure AD SSO application will be able to authenticate through the Azure AD SSO connector.

Step 5: Set email domains and enable the SSO connector

Provide the email domains of your organization at Logto's connector SSO experience tab. This will enable the SSO connector as an authentication method for those users.

Users with email addresses in the specified domains will be redirected to use the SAML SSO connector as their only authentication method.

Please check Azure AD's official documentation for more details about the Azure AD SSO integration.

Save your configuration

Double check you have filled out necessary values in the Logto connector configuration area. Click "Save and Done" (or "Save changes") and the Microsoft Entra ID SAML enterprise SSO connector should be available now.

Enable Microsoft Entra ID SAML enterprise SSO connector in Sign-in Experience

You don’t need to configure enterprise connectors individually, Logto simplifies SSO integration into your applications with just one click.

1. Navigate to: Console > Sign-in experience > Sign-up and sign-in.
2. Enable the "Enterprise SSO" toggle.
3. Save changes.

Once enabled, a "Single Sign-On" button will appear on your sign-in page. Enterprise users with SSO-enabled email domains can access your services using their enterprise identity providers (IdPs).

To learn more about the SSO user experience, including SP-initiated SSO and IdP-initiated SSO, refer to User flows: Enterprise SSO.

Testing and Validation

Return to your Flutter app. You should now be able to sign in with Microsoft Entra ID SAML enterprise SSO. Enjoy!

Further readings

End-user flows: Logto provides a out-of-the-box authentication flows including MFA and enterprise SSO, along with powerful APIs for flexible implementation of account settings, security verification, and multi-tenant experience.

Authorization: Authorization defines the actions a user can do or resources they can access after being authenticated. Explore how to protect your API for native and single-page applications and implement Role-based Access Control (RBAC).

Organizations: Particularly effective in multi-tenant SaaS and B2B apps, the organization feature enable tenant creation, member management, organization-level RBAC, and just-in-time-provisioning.

Customer IAM series Our serial blog posts about Customer (or Consumer) Identity and Access Management, from 101 to advanced topics and beyond.