Google - hippogamesunity/SimpleSignIn GitHub Wiki

Welcome to Simple Google Sign-In wiki!

The asset provides Google sign-in with OAuth 2.0 for Android, iOS, Windows, macOS, Universal Windows Platform (UWP) and WebGL apps made with Unity. You can also get access tokens to make REST API calls to other Google services.

Benefits

Cross-platform user auth for cross-platform games and apps
No plugins, no 3rd party libs, no dependencies
No impact to build size
Get access tokens for integration with other Google services
More security for client-server apps (get an access token on a client, get all user data on a server to avoid tampering)
JSON Web Tokens (JWT) validation
SFSafariViewController is used on iOS (required by App Store review)
Deep linking for Windows (UNITY_STANDALONE_WIN)

Alternatives

Sign-in with Play Games for Android (a part of Google Play Game Services, difficult to setup, super massive with a lot of dependencies, you can't get user email anymore in last versions)
Sign-in with Apple for iOS (native, but there are issues with getting user emails)
3rd party SDK for other platforms

Terminology

Please visit Terminology section

Understanding how it works

Generic workflow (for platforms that support deep linking):
- Your app navigates users to Google Authorization Endpoint using a default web browser (embedded webviews are not allowed)
- Users perform sign-in using their login and password
- Google Authorization Endpoint redirects users to Redirect URI (this can be a deep link when possible) and provides an authorization code to the app (as URI parameters)
- The app is activated and obtains code
- The app exchanges code for access token
- The app requests user data with access token (ID, name, email and other data according access scope defined)
For Android, iOS, macOS, Windows and Universal Windows Platform (platforms that support deep linking):
- Redirect URI is a deep link which activates the app and provides code in URI parameters
Loopback flow for Editor and Windows (optional):
- This flow is optional for Windows (the generic workflow is used by default)
- Redirect URI is http://localhost:PORT/ with a random unused port
- The app listens to localhost using System.Net.HttpListener
- The app obtains code and asks a user to close the browser tab and to return to the app
- Further workflow is the same (exchanging code for access token, requesting user data)
Middleware flow for WebGL (the platform doesn't support deep linking and loopback):
- OAuth Redirect to Authorization Middleware is used to temporary save code
- The app obtains code from Authorization Middleware with a POST request
- Further workflow is the same (exchanging code for access token, requesting user data)

Preconditions

For Android, iOS, macOS, Windows and UWP (platforms that support deep linking): COME UP WITH your Custom URI scheme (or Protocol). It MUST contain the period symbol . and small (LOWERCASE) alphanumeric symbols only (no spaces, no undercores). In my example it is simple.oauth, but it can be jelly.bean (note that Custom URI scheme doesn't have to be the same as your actual package name or bundle id).
For Android, iOS, UWP: enable deep linking as described in Unity documentation or as described below.
For Android: create AndroidManifest.xml inside Assets/Plugins/Android/, SET your Custom URI scheme inside, like <data android:scheme="simple.oauth" />. You can use AndroidManifestExample.xml from the asset as an example, just copy, rename and edit. AGAIN, DON'T FORGET TO REPLACE simple.oauth with your Custom URI scheme!
For iOS and macOS: navigate to Player Settings > Other > Configuration and add your Custom URI scheme to Supported URL schemes. In Xcode, make sure that the URL scheme is added (Register your URL scheme).
For Universal Windows Platform: navigate to Player Settings > Publishing Settings and set Protocol (it MUST contain a period symbol, for example simple.oauth), then enable InternetClient in Capabilities.
For Windows: navigate to Player Settings and enable Resolution and Presentation > Force Single Instance and set Other Settings > Api Compatibility Level = .NET Framework
For Editor: Set Allow downloads over HTTP = Always allowed (Unity 2022+)

Setup steps

Visit Google Cloud > Credentials
Create a new app if needed
Create OAuth client ID
- For Android, iOS, macOS, Windows and UWP: select iOS (for all 3 platforms, it's not a typo) and fill Bundle ID with your app Custom URI scheme or Protocol (see Preconditions). AGAIN, IT SHOULD BE EXACTLY iOS (this is the most common mistake)! Screenshot
- For Editor and Windows (optional): select Desktop app Screenshot
- For WebGL select Web application and provide Authorized JavaScript origins (the URL of your published app) and Authorized redirect URIs (SET Authorization Middleware URL: https://hippogames.dev/api/oauth/redirect) Screenshot
Copy Client ID (check if you didn't copy it with extra spaces)
- For Windows, WebGL and Editor: copy Client secret as well
Configure Resources/GoogleAuthSettings.asset
- For Android, iOS, macOS, Windows and UWP: set Client ID and Custom URI scheme (or Protocol)
- For WebGL, Editor and Windows (optional): set Client ID and Client secret
- Check Access Scopes (openid, email, profile are required to get UserInfo)

Checklist

Custom URI scheme is picked, and it has a different value than simple.oauth
Custom URI scheme is set in 3 places: [1] Google Cloud credentials (Bundle ID), [2] Resources/GoogleAuthSettings.asset, [3] your application manifest (AndroidManifest.xml for Android, Supported URL schemes for iOS, Protocol for UWP)
ClientId is copied to Resources/GoogleAuthSettings.asset (check if you didn't paste it with extra spaces)

Usage

Check our Example scene and C# code of Example.cs
Create an instance of GoogleAuth
Call GoogleAuth.SignIn or GoogleAuth.GetTokenResponse
Create OnSignIn or OnGetTokenResponse callbacks
Build and test
Write a review on the Asset Store :)

API reference for GoogleAuth class

Method	Arguments	Description
GoogleAuth (constructor)	GoogleAuthSettings settings = null	A constructor that accepts an instance of GoogleAuthSettings. If Null is passed, it will load default settings from Resources (GoogleAuthSettings scriptable object).
SignIn	Action<bool, string, UserInfo> callback, bool caching = true	Performs sign-in and returns an instance of UserInfo with `callback`. If `caching` is True, it will return the previously saved UserInfo.
SignOut	bool revokeAccessToken = false	Performs sign-out. Can revoke Access Token if requested.
GetTokenResponse	Action<bool, string, TokenResponse> callback	Returns an instance of TokenResponse which contains AccessToken and other related information (expiration, type and other). It may also contain IdToken (JWT), if requested with `openid` scope, which contains information about the user.
GetAuthorizationCode	Action<bool, string, string> callback	Returns AuthorizationCode. It can be exchanged for AccessToken later (on your backend, for example).
TryResume	Refer to code	This can be called on app startup to continue OAuth. In some scenarios, the app may be terminated while the user performs sign-in on Google website.
SignInAsync		Async version of SignIn.
GetTokenResponseAsync		Async version of GetTokenResponse.

Best practices

Call GoogleAuth.SignIn with caching: true to return cached UserInfo
Call GoogleAuth.SignIn with caching: false to request UserInfo from Google
Call GoogleAuth.GetTokenResponse instead of GoogleAuth.SignIn if you need an access token or an ID token only (and don't need UserInfo)
You can use GoogleAuth.SavedAuth to get TokenResponse or UserInfo (don't forget to check all values for null)
Call GoogleAuth.SignOut when 'Sign out` button is pressed (optional)
Disable debug logs for production by setting GoogleAuth.DebugLog = false

Next steps (optional)

You can add extra access scopes in Resources/GoogleAuthSettings.asset
If you have a backend (server), send TokenResponse to it (to avoid tampering user data when sending from clients to your server)
Validate JSON Web Token (JWT) encoded in TokenResponse.IdToken on your server (refer to JWT class for parsing and signature validation example)
For Editor and Windows (optional), you can modify StandaloneTemplate.html (used by the loopback flow) to edit the message "Success! Please close the browser tab and return to the app."
For Windows, check Settings for Windows
For WebGL, consider deploying your own Authorization Middleware
You can use this asset with async methods, just refer to GoogleAuthAsync.cs for examples

Unity Authentication Service

Refer to Integration with Unity Authentication Service

Can I trust Authorization Middleware? Is it secure to use a 3rd party service?

Authorization Middleware can't exchange code for access token without knowing both client secret and code verifier. Only the app itself can exchange code for access token.
It's recommended to deploy your own trusted Authorization Middleware to handle sensitive data. Please refer to Authorization Middleware article.

Notes

Please refer to User data disclosure
Google OpenID is not the same as Play Games ID (Google Play Game Services), but they both have the same user email
Don't use default credentials that come with the asset in production, they are for test purposes only and can be disabled/blocked
You can use the same iOS credentials for Android, iOS, Windows and UWP
Check Manual cancellation if needed

Known issues

Please visit Common issues section

Supported browsers

Please visit Supported browsers section

Try in real apps

Navigate: Menu/Google Drive Backup/Sign in with Google (for WebGL: Account/Sign in with Google).