Association de comptes Google avec OAuth

Les comptes sont associés à l'aide de flux implicites et code d'autorisation OAuth 2.0. Votre service doit être compatible avec les points de terminaison d'autorisation et d'échange de jetons conformes à OAuth 2.0.

In the implicit flow, Google opens your authorization endpoint in the user's browser. After successful sign in, you return a long-lived access token to Google. This access token is now included in every request sent from Google.

In the authorization code flow, you need two endpoints:

• The authorization endpoint, which presents the sign-in UI to your users that aren't already signed in. The authorization endpoint also creates a short-lived authorization code to record users' consent to the requested access.

• The token exchange endpoint, which is responsible for two types of exchanges:

  1. Exchanges an authorization code for a long-lived refresh token and a short-lived access token. This exchange happens when the user goes through the account linking flow.
  2. Exchanges a long-lived refresh token for a short-lived access token. This exchange happens when Google needs a new access token because the one it had expired.

Choose an OAuth 2.0 flow

Although the implicit flow is simpler to implement, Google recommends that access tokens issued by the implicit flow never expire. This is because the user is forced to link their account again after a token expires with the implicit flow. If you need token expiration for security reasons, we strongly recommend that you use the authorization code flow instead.

Note: Use the following buttons to choose which OAuth 2.0 flow you want to implement. If needed, the content of this guide will reload to match your choice.

Implicit flow Authorization code

Design guidelines

This section describes the design requirements and recommendations for the user screen that you host for OAuth linking flows. After it's called by Google's app, your platform displays a sign in to Google page and account linking consent screen to the user. The user is directed back to Google's app after giving their consent to link accounts.

Figure 1. Account linking user sign in to Google and consent screens.

Requirements

1. You must communicate that the user’s account will be linked to Google, not a specific Google product like Google Home or Google Assistant.

Recommendations

We recommend that you do the following:

1. Display Google's Privacy Policy. Include a link to Google’s Privacy Policy on the consent screen.

2. Data to be shared. Use clear and concise language to tell the user what data of theirs Google requires and why.

3. Clear call-to-action. State a clear call-to-action on your consent screen, such as “Agree and link.” This is because users need to understand what data they're required to share with Google to link their accounts.

4. Ability to cancel. Provide a way for users to go back or cancel, if they choose not to link.

5. Clear sign-in process. Ensure that users have clear method for signing in to their Google account, such as fields for their username and password or Sign in with Google.

6. Ability to unlink. Offer a mechanism for users to unlink, such as a URL to their account settings on your platform. Alternatively, you can include a link to Google Account where users can manage their linked account.

7. Ability to change user account. Suggest a method for users to switch their account(s). This is especially beneficial if users tend to have multiple accounts.

   • If a user must close the consent screen to switch accounts, send a recoverable error to Google so the user can sign in to the desired account with OAuth linking and the implicit flow.

8. Include your logo. Display your company logo on the consent screen. Use your style guidelines to place your logo. If you wish to also display Google's logo, see Logos and trademarks.

Figure 2. Design guidelines for user sign in to Google and consent screens.

Create the project

Note: You can reuse an existing project and do not need to create a new project primarily for account linking.

To create your project to use account linking:

1. Go to the Google API Console.
2. Cliquez sur Créer un projet .
3. Saisissez un nom ou acceptez la suggestion générée.
4. Confirmez ou modifiez les champs restants.
5. Cliquez sur Créer .

Pour afficher votre ID de projet:

1. Go to the Google API Console.
2. Trouvez votre projet dans le tableau de la page de destination. L'ID du projet apparaît dans la colonne ID .

Configure your OAuth Consent Screen

The Google Account Linking process includes a consent screen which tells users the application requesting access to their data, what kind of data they are asking for and the terms that apply. You will need to configure your OAuth consent screen before generating a Google API client ID.

1. Open the OAuth consent screen page of the Google APIs console.
2. If prompted, select the project you just created.

3. On the "OAuth consent screen" page, fill out the form and click the “Save” button.

   Application name: The name of the application asking for consent. The name should accurately reflect your application and be consistent with the application name users see elsewhere. The application name will be shown on the Account Linking consent screen.

   Application logo: An image on the consent screen that will help users recognize your app. The logo is shown on Account linking consent screen and on account settings

   Support email: For users to contact you with questions about their consent.

   Scopes for Google APIs: Scopes allow your application to access your user's private Google data. For the Google Account Linking use case, default scope (email, profile, openid) is sufficient, you don’t need to add any sensitive scopes. It is generally a best practice to request scopes incrementally, at the time access is required, rather than up front. Learn more.

   Authorized domains: To protect you and your users, Google only allows applications that authenticate using OAuth to use Authorized Domains. Your applications' links must be hosted on Authorized Domains. Learn more.

   Application Homepage link: Home page for your application. Must be hosted on an Authorized Domain.

   Application Privacy Policy link: Shown on Google Account Linking consent screen. Must be hosted on an Authorized Domain.

   Application Terms of Service link (Optional): Must be hosted on an Authorized Domain.

   

   Figure 1. Google Account Linking Consent Screen for a fictitious Application, Tunery

4. Check "Verification Status", if your application needs verification then click the "Submit For Verification" button to submit your application for verification. Refer to OAuth verification requirements for details.

Implémenter votre serveur OAuth

Pour prendre en charge le flux implicite OAuth 2.0, votre service accorde une autorisation un point de terminaison unique disponible via HTTPS. Ce point de terminaison est responsable de l'authentification l'obtention du consentement des utilisateurs pour l'accès aux données. Le point de terminaison d'autorisation présente une interface utilisateur de connexion aux utilisateurs qui ne sont pas déjà connectés et enregistre autoriser l'accès demandé.

Lorsqu'une application Google doit appeler l'une des API autorisées de votre service, Google utilise ce point de terminaison pour obtenir l'autorisation de vos utilisateurs d'appeler ces API en son nom.

Une session de flux implicite OAuth 2.0 typique lancée par Google possède le flux suivant:

1. Google ouvre votre point de terminaison d'autorisation dans le navigateur de l'utilisateur. La se connecte (s'il ne l'est pas déjà) et autorise Google à accéder à leurs données avec votre API, s'ils ne l'ont pas déjà accordé.
2. Votre service crée un jeton d'accès et le renvoie à Google Pour ce faire, redirigez le navigateur de l'utilisateur vers Google associé à la requête.
3. Google appelle les API de votre service et associe le jeton d'accès chaque requête. Votre service vérifie que le jeton d'accès accorde à Google l'autorisation d'accès à l'API, puis termine l'appel d'API.

Gérer les requêtes d'autorisation

Lorsqu'une application Google doit associer un compte via une méthode OAuth 2.0 flux implicite, Google redirige l'utilisateur vers votre point de terminaison d'autorisation qui inclut les paramètres suivants:

Paramètres du point de terminaison de l'autorisation
client_id	ID client que vous avez attribué à Google.
redirect_uri	URL à laquelle vous envoyez la réponse à cette requête.
state	Une valeur de tenue de registre renvoyée à Google telle quelle dans le l'URI de redirection.
response_type	Type de valeur à renvoyer dans la réponse. Pour l'authentification OAuth 2.0 le type de réponse est toujours token.
user_locale	Le paramètre linguistique du compte Google RFC5646 format utilisé pour localiser votre contenu dans la langue préférée de l'utilisateur.

Par exemple, si votre point de terminaison d'autorisation est disponible https://myservice.example.com/auth, une requête peut se présenter comme suit:

GET https://myservice.example.com/auth?client_id=GOOGLE_CLIENT_ID&redirect_uri=REDIRECT_URI&state=STATE_STRING&response_type=token&user_locale=LOCALE

Pour que votre point de terminaison d'autorisation traite les requêtes de connexion, procédez comme suit : étapes:

1. Vérifiez les valeurs client_id et redirect_uri pour pour empêcher l'octroi d'accès à des applications clientes non intentionnelles ou mal configurées:

   • Vérifiez que client_id correspond à l'ID client que vous attribué à Google.
   • Vérifiez que l'URL spécifiée par redirect_uri a la forme suivante:

     https://oauth-redirect.googleusercontent.com/r/YOUR_PROJECT_ID
     https://oauth-redirect-sandbox.googleusercontent.com/r/YOUR_PROJECT_ID
     

2. Vérifiez si l'utilisateur est connecté à votre service. Si l'utilisateur n'est pas signé suivez la procédure de connexion ou d'inscription de votre service.

3. Générez un jeton d'accès que Google utilisera pour accéder à votre API. La Le jeton d'accès peut correspondre à n'importe quelle valeur de chaîne, mais il doit représenter de manière unique le user et le client pour lequel le jeton est destiné et ne doit pas être devinable.

4. Envoyer une réponse HTTP qui redirige le navigateur de l'utilisateur vers l'URL spécifiée par le paramètre redirect_uri. Incluez tous les les paramètres suivants dans le fragment d'URL:

   • access_token: jeton d'accès que vous venez de générer
   • token_type: chaîne bearer
   • state: valeur de l'état non modifié de l'original demander

   Voici un exemple de l'URL obtenue:

   https://oauth-redirect.googleusercontent.com/r/YOUR_PROJECT_ID#access_token=ACCESS_TOKEN&token_type=bearer&state=STATE_STRING

Le gestionnaire de redirection OAuth 2.0 de Google reçoit le jeton d'accès et confirme que la valeur state n'a pas changé. Une fois que Google a obtenu pour votre service, le jeton est associé aux appels suivants à vos API de service.

Handle userinfo requests

The userinfo endpoint is an OAuth 2.0 protected resource that return claims about the linked user. Implementing and hosting the userinfo endpoint is optional, except for the following use cases:

• Linked Account Sign-In with Google One Tap.
• Frictionless subscription on AndroidTV.

After the access token has been successfully retrieved from your token endpoint, Google sends a request to your userinfo endpoint to retrieve basic profile information about the linked user.

userinfo endpoint request headers
Authorization header	The access token of type Bearer.

For example, if your userinfo endpoint is available at https://myservice.example.com/userinfo, a request might look like the following:

GET /userinfo HTTP/1.1
Host: myservice.example.com
Authorization: Bearer ACCESS_TOKEN

For your userinfo endpoint to handle requests, do the following steps:

1. Extract access token from the Authorization header and return information for the user associated with the access token.
2. If the access token is invalid, return an HTTP 401 Unauthorized error with using the WWW-Authenticate Response Header. Below is an example of a userinfo error response:

   HTTP/1.1 401 Unauthorized
   WWW-Authenticate: error="invalid_token",
   error_description="The Access Token expired"
   

   If a 401 Unauthorized, or any other unsuccessful error response is returned during the linking process, the error will be non-recoverable, the retrieved token will be discarded and the user will have to initiate the linking process again.

3. If the access token is valid, return and HTTP 200 response with the following JSON object in the body of the HTTPS response:

   {
   "sub": "USER_UUID",
   "email": "EMAIL_ADDRESS",
   "given_name": "FIRST_NAME",
   "family_name": "LAST_NAME",
   "name": "FULL_NAME",
   "picture": "PROFILE_PICTURE",
   }
   

   If your userinfo endpoint returns an HTTP 200 success response, the retrieved token and claims are registered against the user's Google account.

   userinfo endpoint response
   sub	A unique ID that identifies the user in your system.
   email	Email address of the user.
   given_name	Optional: First name of the user.
   family_name	Optional: Last name of the user.
   name	Optional: Full name of the user.
   picture	Optional: Profile picture of the user.

Valider votre intégration

You can validate your implementation by using the OAuth 2.0 Playground tool.

In the tool, do the following steps:

1. Click Configuration to open the OAuth 2.0 Configuration window.
2. In the OAuth flow field, select Client-side.
3. In the OAuth Endpoints field, select Custom.
4. Specify your OAuth 2.0 endpoint and the client ID you assigned to Google in the corresponding fields.
5. In the Step 1 section, don't select any Google scopes. Instead, leave this field blank or type a scope valid for your server (or an arbitrary string if you don't use OAuth scopes). When you're done, click Authorize APIs.
6. In the Step 2 and Step 3 sections, go through the OAuth 2.0 flow and verify that each step works as intended.

You can validate your implementation by using the Google Account Linking Demo tool.

In the tool, do the following steps:

1. Click the Sign-in with Google button.
2. Choose the account you'd like to link.
3. Enter the service ID.
4. Optionally enter one or more scopes that you will request access for.
5. Click Start Demo.
6. When prompted, confirm that you may consent and deny the linking request.
7. Confirm that you are redirected to your platform.