Authenticate with Firebase using a custom authentication system and Unity

You can integrate Firebase Authentication with a custom authentication system by modifying your authentication server to produce custom signed tokens when a user successfully signs in. Your app receives this token and uses it to authenticate with Firebase.

Before you begin

    Before you can use the Firebase Authentication, you will need to create a Firebase project, and add the Firebase Unity SDK packages to your Unity project.

    Setup:

    Prerequisites

    Android

    iOS

    • Unity 5.0 or later.
    • Xcode 7.0 or later.

    If you don't have a Unity project already, you can download one of our quickstart samples and experiment with a specific Firebase feature. If you're using a quickstart, remember to get the bundle identifier from the project settings; you'll need it for the next step.

    Set up your app in Firebase console

    To add Firebase to your app you'll need a Firebase project and a Firebase configuration file for your app.

    Create a Firebase project in the Firebase console, if you don't already have one. If you already have an existing Google project associated with your mobile app, click Import Google Project. Otherwise, click Create New Project.

    Android

    1. Click Add Firebase to your Android app and follow the setup steps. If you're importing an existing Google project, this may happen automatically and you can just download the config file.
    2. When prompted, enter your app's package name. It's important to enter the package name your app is using; this can only be set when you add an app to your Firebase project.
    3. Download a google-services.json file when instructed. You can redownload this file again at any time.
    4. Copy this file to anywhere inside your project's assets folder.

    IOs

    1. Click Add Firebase to your iOS app and follow the setup steps. If you're importing an existing Google project, this may happen automatically and you can just download the config file.
    2. When prompted, enter your app's bundle ID. It's important to enter the bundle ID your app is using; this can only be set when you add an app to your Firebase project.
    3. Download a GoogleService-Info.plist file when instructed. You can redownload this file again at any time.
    4. Add the GoogleService-Info.plist file to the project.

    5. Drag the GoogleService-Info.plist downloaded from the Firebase console into any folder in the Unity project.

    Add the Firebase Unity SDK to your app

    1. Download the Firebase Unity SDK
    2. Select the Assets > Import Package > Custom Package menu item.
    3. Import the FirebaseAuth.unitypackage package from the Firebase Unity SDK, downloaded previously.
    4. When the Import Unity Package window appears, click the Import button.

    Build your app

    Android

    1. Select the File > Build Settings menu option.
    2. Select Android in the Platform list.
    3. Click Switch Platform to select Android as the target platform.
    4. Wait for the spinner (compiling) icon in the bottom right corner of the Unity status bar to stop.
    5. Click Build and Run.

    iOS

    1. Select the File > Build Settings menu option.
    2. Select iOS in the Platform list.
    3. Click Switch Platform to select iOS as the target platform.
    4. Wait for the spinner (compiling) icon in the bottom right corner of the Unity status bar to stop.
    5. Click Build and Run.

  1. Get your project's server keys:
    1. Go to the Service Accounts page in your project's settings.
    2. Click Generate New Private Key at the bottom of the Firebase Admin SDK section of the Service Accounts page.
    3. The new service account's public/private key pair is automatically saved on your computer. Copy this file to your authentication server.

Authenticate with Firebase

The FirebaseAuth class is the gateway for all API calls. It is accessable through FirebaseAuth.DefaultInstance.
Firebase.Auth.FirebaseAuth auth = Firebase.Auth.FirebaseAuth.DefaultInstance;

Call Firebase.Auth.FirebaseAuth.SignInWithCustomTokenAsync with the token from your authentication server.

  1. When users sign in to your app, send their sign-in credentials (for example, their username and password) to your authentication server. Your server checks the credentials and returns a custom token if they are valid.
  2. After you receive the custom token from your authentication server, pass it to Firebase.Auth.FirebaseAuth.SignInWithCustomTokenAsync to sign in the user:
    auth.SignInWithCustomTokenAsync(custom_token).ContinueWith(task => {
      if (task.IsCanceled) {
        Debug.LogError("SignInWithCustomTokenAsync was canceled.");
        return;
      }
      if (task.IsFaulted) {
        Debug.LogError("SignInWithCustomTokenAsync encountered an error: " + task.Exception);
        return;
      }
    
      Firebase.Auth.FirebaseUser newUser = task.Result;
      Debug.LogFormat("User signed in successfully: {0} ({1})",
          newUser.DisplayName, newUser.UserId);
    });
    

Next steps

After a user signs in for the first time, a new user account is created and linked to the credentials—that is, the user name and password, or auth provider information—the user signed in with. This new account is stored as part of your Firebase project, and can be used to identify a user across every app in your project, regardless of how the user signs in.

  • In your apps, you can get the user's basic profile information from the Firebase.Auth.FirebaseUser object:

    Firebase.Auth.FirebaseUser user = auth.CurrentUser;
    if (user != null) {
      string name = user.DisplayName;
      string email = user.Email;
      System.Uri photo_url = user.PhotoUrl;
      // The user's Id, unique to the Firebase project.
      // Do NOT use this value to authenticate with your backend server, if you
      // have one; use User.TokenAsync() instead.
      string uid = user.UserId;
    }
    
  • In your Firebase Realtime Database and Cloud Storage Security Rules, you can get the signed-in user's unique user ID from the auth variable, and use it to control what data a user can access.

You can allow users to sign in to your app using multiple authentication providers by linking auth provider credentials to an existing user account.

To sign out a user, call SignOut():

auth.SignOut();

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