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descope / descope-flutter

Flutter library used to integrate with Descope

Home Page:https://docs.descope.com

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Descope for Flutter

The Descope package for flutter provides convenient access to the Descope user management and authentication APIs for applications written for Flutter. You can read more on the Descope Website.

Features

Quickstart

A Descope Project ID is required to initialize the SDK. Find it on the project page in the Descope Console.

import 'package:descope/descope.dart';

// Where your application state is being created
Descope.projectId = '<Your-Project-ID>';
await Descope.sessionManager.loadSession();

Authenticate the user in your application by starting one of the authentication methods. For example, let's use OTP via email:

// sends an OTP code to the given email address
await Descope.otp.signUp(method: DeliveryMethod.email, loginId: 'andy@example.com');

Finish the authentication by verifying the OTP code the user entered:

// if the user entered the right code the authentication is successful
final authResponse = await Descope.otp.verify(method: DeliveryMethod.email, loginId: 'andy@example.com', code: code);

// we create a DescopeSession object that represents an authenticated user session
final session = DescopeSession.fromAuthenticationResponse(authResponse);

// the session manager automatically takes care of persisting the session
// and refreshing it as needed
Descope.sessionManager.manageSession(session);

On the next application launch check if there's a logged in user to decide which screen to show:

// check if we have a valid session from a previous launch and that it hasn't expired yet
if (Descope.sessionManager.session?.refreshToken?.isExpired == true) {
    // Show main UI
} else {
    // Show login UI
}

Use the active session to authenticate outgoing API requests to the application's backend:

request.setAuthorization(Descope.sessionManager);

Session Management

The DescopeSessionManager class is used to manage an authenticated user session for an application.

The session manager takes care of loading and saving the session as well as ensuring that it's refreshed when needed. When the user completes a sign in flow successfully you should set the DescopeSession object as the active session of the session manager.

final authResponse = await Descope.otp.verify(method: DeliverMethod.Email, loginId: 'andy@example.com', code: '123456');
final session = DescopeSession.fromAuthenticationResponse(authResponse);
Descope.sessionManager.manageSession(session);

The session manager can then be used at any time to ensure the session is valid and to authenticate outgoing requests to your backend with a bearer token authorization header.

request.setAuthorization(Descope.sessionManager);

If your backend uses a different authorization mechanism you can of course use the session JWT directly instead of the extension function. You can either add another extension function on http.Request such as the one above, or you can do the following.

await Descope.sessionManager.refreshSessionIfNeeded();
final sessionJwt = Descope.sessionManager.session?.sessionJwt;
if (sessionJwt != null) {
    request.headers['X-Auth-Token'] = sessionJwt;
} else {
    // unauthorized
}

When the application is relaunched the DescopeSessionManager can load the existing session and you can check straight away if there's an authenticated user.

await Descope.sessionManager.loadSession();

If you prefer to call loadSession in your main() function, before the platform's runApp() function is called, then you'll need to ensure the widget bindings are initialized first:

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  Descope.projectId = '...';
  await Descope.sessionManager.loadSession();

  final session = Descope.sessionManager.session;
  if (session != null) {
    print('User is logged in: ${session.user}');
  }

  runApp(
    ...
  );
}

When the user wants to sign out of the application we revoke the active session and clear it from the session manager:

final refreshJwt = Descope.sessionManager.session?.refreshJwt;
if (refreshJwt != null) {
  Descope.auth.logout(refreshJwt);
  Descope.sessionManager.clearSession();
}

You can customize how the DescopeSessionManager behaves by using your own storage and lifecycle objects. See the documentation for more details.

Custom Claims

You can request for a sign in operation to add additional custom claims to the user's JWT during authentication.

For example, the following code starts an OTP sign in and requests a custom claim with the authenticated user's full name:

const options = SignInOptions(customClaims: {'name': '{{user.name}}'});
await Descope.otp.signIn(method: DeliveryMethod.email, loginId: 'desmond_c@mail.com', options: options);

Note that any custom claims added via this method are considered insecure and will be nested under the nsec custom claim.

Error Handling

All authentication operations throw a DescopeException in case of a failure. There are several ways to catch and handle a DescopeException, and you can use whichever one is more appropriate in each specific use case.

try {
  final authResponse = await Descope.otp.verify(method: DeliveryMethod.email, loginId: loginId, code: code);
  final session = DescopeSession.fromAuthenticationResponse(authResponse);
  Descope.sessionManager.manageSession(session);
} on DescopeException catch (e) {
  switch(e) {
    case DescopeException.wrongOTPCode:
    case DescopeException.invalidRequest:
      showBadCodeAlert();
      break;
    case DescopeException.networkError:
      showNetworkErrorRetry();
      break;
    default:
      showUnexpectedErrorAlert(with: e);
  }
}

See the DescopeException class for specific error values. Note that not all API errors are listed in the SDK yet. Please let us know via a Github issue or pull request if you need us to add any entries to make your code simpler.

Running Flows

We can authenticate users by building and running Flows. Flows are built in the Descope flow editor. The editor allows you to easily define both the behavior and the UI that take the user through their authentication journey. Read more about it in the Descope getting started guide.

Setup #1: Define and host your flow

Before we can run a flow, it must first be defined and hosted. Every project comes with predefined flows out of the box. You can customize your flows to suit your needs and host it. Follow the getting started guide for more details. You can host the flow yourself or leverage Descope's hosted flow page. Read more about it here. You can also check out the auth-hosting repo itself.

(Android Only) Setup #2: Enable App Links

Running a flow via the Flutter SDK, when targeting Android, requires setting up App Links. This is essential for the SDK to be notified when the user has successfully authenticated using a flow. Once you have a domain set up and verified for sending App Links, you'll need to handle the incoming deep links in your app:

Define a route to handle the App Link sent at the end of a flow

this code example demonstrates how app links should be handled - you can customize it to fit your app

final _router = GoRouter(
  routes: [
    GoRoute(
      path: '/',
      builder: (_, __) => const MyHomePage(title: 'Flutter Demo Home Page'), // Your main app
      routes: [
        GoRoute(
          path: 'auth', // This path needs to correspond to the deep link you configured in your manifest - see below
          redirect: (context, state) async {
            try {
              Descope.flow.exchange(state.uri); // Call exchange to complete the flow
            } catch (e) {
              // Handle errors here
            }
            return '/'; // This route doesn't display anything but returns the root path where the user will be signed in
          },
        ),
        // Magic Link handling will be here. See the documentation below.
      ],
    ),
  ],
);

Add a matching Manifest declaration

Read more about the flutter specific meta-data tag mentioned here in the official documentation.

<activity
        android:name=".MainActivity"
        android:exported="true"
        android:launchMode="singleTask"
        android:theme="@style/LaunchTheme"
        android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
        android:hardwareAccelerated="true"
        android:windowSoftInputMode="adjustResize"> <!-- exported, singleTop are enabled by default but singleTask is required for the magic links to work -->
        
    <!-- add the following at the end of the activity tag, after anything you have defined currently -->
    
    <meta-data android:name="flutter_deeplinking_enabled" android:value="true" />
    <intent-filter android:autoVerify="true"> <!-- autoVerify required for app links -->
        <action android:name="android.intent.action.VIEW" />
        <category android:name="android.intent.category.DEFAULT" />
        <category android:name="android.intent.category.BROWSABLE" />
        <!-- replace with your host, the path can change must must be reflected when running the flow -->
        <!-- the path should correspond with the routing path defined above -->
        <data android:scheme="https" android:host="<YOUR_HOST_HERE>" android:path="/auth" />
        <!-- see magic link setup below for more details -->
        <data android:scheme="https" android:host="<YOUR_HOST_HERE>" android:path="/magiclink" />
    </intent-filter>
</activity>

(OPTIONAL) Setup #3: Support Magic Link Redirects

Supporting Magic Link authentication in flows requires some platform specific setup:

Regardless of the platform, another path is required to handle magic link redirects specifically. For the sake of this README, let's name it /magiclink

Define a route to handle the App Link or Universal Link sent when a magic link is sent

this code example demonstrates how app links or universal links should be handled - you can customize it to fit your app

final _router = GoRouter(
  routes: [
    GoRoute(
      path: '/',
      builder: (_, __) => const MyHomePage(title: 'Flutter Demo Home Page'),
      routes: [
        GoRoute(
          path: 'auth',
          redirect: (context, state) {
            try {
              Descope.flow.exchange(state.uri);
            } catch (e) {
              // Handle errors here
            }
            return '/';
          },
        ),
        // Adding the magic link handling here:
        GoRoute(
          path: 'magiclink', // This path needs to correspond to the deep link you configured in your manifest or associated domain - see below
          redirect: (context, state) async {
            try {
              await Descope.flow.resume(state.uri); // Resume the flow after returning from a magic link
            } catch (e) {
              // Handle errors here
            }
            return '/'; // This route doesn't display anything but returns the root path where the user will be signed in
          },
        ),
      ],
    ),
  ],
);

Run a Flow

After completing the prerequisite steps, it is now possible to run a flow. The flow will run in a Chrome Custom Tab on Android, or via ASWebAuthenticationSession on iOS. Run the flow by calling the flow start function:

final authResponse = await Descope.flow.start('<URL_FOR_FLOW_IN_SETUP_#1>', deepLinkUrl: '<URL_FOR_APP_LINK_IN_SETUP_#2>');
final session = DescopeSession.fromAuthenticationResponse(authResponse);
Descope.sessionManager.manageSession(session);

When running on iOS nothing else is required. When running on Android, Descope.flow.exchange() function must be called. See the app link setup for more details.

Authentication Methods

We can authenticate users by using any combination of the authentication methods supported by this SDK. Here are some examples for how to authenticate users:

OTP Authentication

Send a user a one-time password (OTP) using your preferred delivery method (email / SMS). An email address or phone number must be provided accordingly.

The user can either sign up, sign in or sign up or in

// Every user must have a loginID. All other user information is optional
final maskedEmail = await Descope.otp.signUp(method: DeliveryMethod.email, loginId: 'desmond_c@mail.com',
    details: SignUpDetails(name: 'Desmond Copeland'));

The user will receive a code using the selected delivery method. Verify that code using:

final authResponse = await Descope.otp.verify(method: DeliveryMethod.email, loginId: 'desmond_c@mail.com', code: '123456');

Magic Link

Send a user a Magic Link using your preferred delivery method (email / SMS). The Magic Link will redirect the user to a page where the attached token needs to be verified. Depending on the target, it might be required to use deep links to return to the app. This redirection can be configured in code, or globally in the Descope Console

The user can either sign up, sign in or sign up or in

// If configured globally, the redirect URL is optional. If provided however, it will be used
// instead of any global configuration
await Descope.magicLink.signUp(method: DeliveryMethod.email, loginId: 'desmond_c@mail.com',
    details: SignUpDetails(name: 'Desmond Copeland'), redirectUrl: 'https://your-redirect-address.com/verify');

To verify a magic link, your redirect page must call the validation function on the token (t) parameter (https://your-redirect-address.com/verify?t=<token>):

final authResponse = await Descope.magicLink.verify(token: '<token>');

Enchanted Link

Using the Enchanted Link APIs enables users to sign in by clicking a link delivered to their email address. The email will include 3 different links, and the user will have to click the right one, based on the 2-digit number that is displayed when initiating the authentication process.

This method is similar to Magic Link but differs in two major ways:

  • The user must choose the correct link out of the three, instead of having just one single link.
  • This supports cross-device clicking, meaning the user can try to log in on one device, like a computer, while clicking the link on another device, for instance a mobile phone.

The Enchanted Link will redirect the user to page where the its token needs to be verified. This redirection can be configured in code per request, or set globally in the Descope Console.

The user can either sign up, sign in or sign up or in

// If configured globally, the redirect URL is optional. If provided however, it will be used
// instead of any global configuration
final enchantedLinkResponse = await Descope.enchantedLink.signUp(loginId: 'desmond_c@mail.com',
    details: SignUpDetails(name: 'Desmond Copeland'), redirectUrl: 'https://your-redirect-address.com/verify');

Inform the user which link is the correct one, using enchantedLinkResponse.linkId. After that, start polling for a valid session. It will be returned once the user clicks on the correct link (assuming the redirected web page calls the validate method);

final authResponse = await Descope.enchantedLink.pollForSession(pendingRef: enchantedLinkResponse.pendingRef);

OAuth

Users can authenticate using their social logins, using the OAuth protocol. Configure your OAuth settings on the Descope console. It is recommended to use flutter_web_auth to handle the redirect and code extraction.

To start a flow call:

import 'package:flutter_web_auth/flutter_web_auth.dart';

// Choose an oauth provider out of the supported providers
// If configured globally, the redirect URL is optional. If provided however, it will be used
// instead of any global configuration.
final authUrl = await Descope.oauth.start(provider: OAuthProvider.google, redirectUrl: 'exampleauthschema://my-app.com/handle-oauth');

Take the generated URL and authenticate the user using flutter_web_auth (read more here). The user will authenticate with the authentication provider, and will be redirected back to the redirect URL, with an appended code HTTP URL parameter. Exchange it to validate the user:

// Redirect the user to the returned URL to start the OAuth redirect chain
final result = await FlutterWebAuth.authenticate(url: authUrl, callbackUrlScheme: 'exampleauthschema');
// Extract the returned code
final code = Uri.parse(result).queryParameters['code'];
// Exchange code for an authentication response
final authResponse = await Descope.oauth.exchange(code: code!);

SSO/SAML

Users can authenticate to a specific tenant using SAML or Single Sign On. Configure your SSO/SAML settings on the Descope console. It is recommended to use flutter_web_auth to handle the redirect and code extraction.

To start a flow call:

// Choose which tenant to log into
// If configured globally, the return URL is optional. If provided however, it will be used
// instead of any global configuration.
final authUrl = await Descope.sso.start(emailOrTenantId: 'my-tenant-ID', redirectUrl: 'exampleauthschema://my-app.com/handle-saml');

Take the generated URL and authenticate the user using flutter_web_auth (read more here). The user will authenticate with the authentication provider, and will be redirected back to the redirect URL, with an appended code HTTP URL parameter. Exchange it to validate the user:

// Redirect the user to the returned URL to start the OAuth redirect chain
final result = await FlutterWebAuth.authenticate(url: authUrl, callbackUrlScheme: 'exampleauthschema');
// Extract the returned code
final code = Uri.parse(result).queryParameters['code'];
// Exchange code for an authentication response
final authResponse = await Descope.sso.exchange(code: code!);

TOTP Authentication

The user can authenticate using an authenticator app, such as Google Authenticator. Sign up like you would using any other authentication method. The sign up response will then contain a QR code image that can be displayed to the user to scan using their mobile device camera app, or the user can enter the key manually or click on the link provided by the provisioningURL.

Existing users can add TOTP using the update function.

// Every user must have a loginID. All other user information is optional
final totpResponse = await Descope.totp.signUp(loginId: 'desmond@descope.com', details: SignUpDetails(name: 'Desmond Copeland'));

// Use one of the provided options to have the user add their credentials to the authenticator
// totpResponse.provisioningUrl
// totpResponse.image
// totpResponse.key

There are 3 different ways to allow the user to save their credentials in their authenticator app - either by clicking the provisioning URL, scanning the QR image or inserting the key manually. After that, signing in is done using the code the app produces.

final authResponse = await Descope.totp.verify(loginId: 'desmond@descope.com', code: '123456');

Password Authentication

It is possible to authenticate a user using a password. Passwords are a legacy way of authentication. Each of the passwordless methods above are better from a security and usability perspective. Passwords are disabled by default in the Descope Console password settings. Make sure to enable it before attempting authentication. The user can either sign up or sign in

// Every user must have a loginID. All other user information is optional
final authResponse = await Descope.password.signUp(loginId: 'desmond_c@mail.com', password: 'cleartext-password',
    details: SignUpDetails(name: 'Desmond Copeland'));

Additional Information

To learn more please see the Descope Documentation and API reference page.

Contact Us

If you need help you can email Descope Support

License

The Descope SDK for Flutter is licensed for use under the terms and conditions of the MIT license Agreement.

About

Flutter library used to integrate with Descope

https://docs.descope.com

appauthenticationdescopeflutterflutter-sdkmobilenativesdkweb

License:MIT License

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