Связывание аккаунта Google с OAuth

Учетные записи связаны с использованием неявных потоков кода авторизации и неявных потоков OAuth 2.0, являющихся отраслевым стандартом. Ваша служба должна поддерживать конечные точки авторизации и обмена токенами, совместимые с OAuth 2.0.

В неявном потоке Google открывает вашу конечную точку авторизации в браузере пользователя. После успешного входа вы возвращаете долговременный токен доступа в Google. Этот токен доступа теперь включается в каждый запрос, отправляемый из Google.

В потоке кода авторизации вам нужны две конечные точки:

  • Конечная точка авторизации , которая представляет пользовательский интерфейс для входа пользователям, которые еще не вошли в систему. Конечная точка авторизации также создает кратковременный код авторизации для записи согласия пользователей на запрошенный доступ.

  • Конечная точка обмена токенами, которая отвечает за два типа обмена:

    1. Обменивает код авторизации на долгоживущий токен обновления и недолговечный токен доступа. Этот обмен происходит, когда пользователь проходит процесс связывания учетной записи.
    2. Заменяет долгоживущий токен обновления на недолговечный токен доступа. Этот обмен происходит, когда Google нужен новый токен доступа, потому что срок его действия истек.

Выберите поток OAuth 2.0

Хотя неявный поток реализовать проще, Google рекомендует, чтобы токены доступа, выдаваемые неявным потоком, никогда не истекали. Это связано с тем, что пользователь вынужден снова связать свою учетную запись после истечения срока действия токена с неявным потоком. Если вам требуется истечение срока действия токена по соображениям безопасности, мы настоятельно рекомендуем вместо этого использовать поток кода авторизации .

потока

Рекомендации по дизайну

В этом разделе описаны требования к дизайну и рекомендации для экрана пользователя, который вы размещаете для потоков связывания OAuth. После вызова приложением Google на вашей платформе отображается страница входа в Google и экран согласия учетной записи, связывающий пользователя с пользователем. Пользователь возвращается в приложение Google после того, как дает свое согласие на связывание учетных записей.

На этом рисунке показаны шаги, необходимые пользователю для привязки своей учетной записи Google к вашей системе аутентификации. На первом снимке экрана показана ссылка, инициированная пользователем с вашей платформы. На втором изображении показан вход пользователя в Google, а на третьем показано согласие и подтверждение пользователя для привязки его учетной записи Google к вашему приложению. На последнем снимке экрана показана успешно связанная учетная запись пользователя в приложении Google.
Рис. 1. Аккаунт, связывающий пользователя со входом в Google и экранами согласия.

Требования

  1. Вы должны сообщить, что учетная запись пользователя будет связана с Google, а не с конкретным продуктом Google, таким как Google Home или Google Assistant.

Рекомендации

Мы рекомендуем вам сделать следующее:

  1. Показать Политику конфиденциальности Google. Включите ссылку на Политику конфиденциальности Google на экране согласия.

  2. Данные для совместного использования. Используйте четкий и лаконичный язык, чтобы сообщить пользователю, какие данные требуются Google и почему.

  3. Четкий призыв к действию. Сформулируйте четкий призыв к действию на экране согласия, например «Согласиться и дать ссылку». Это связано с тем, что пользователи должны понимать, какими данными они должны делиться с Google, чтобы связать свои учетные записи.

  4. Возможность отмены. Предоставьте пользователям возможность вернуться или отменить, если они решат не связываться.

  5. Очистить процесс входа. Убедитесь, что у пользователей есть четкий способ входа в свою учетную запись Google, например поля для имени пользователя и пароля или Войти с помощью Google .

  6. Возможность отвязать. Предложите пользователям механизм отмены связи, например URL-адрес их настроек учетной записи на вашей платформе. Кроме того, вы можете включить ссылку на учетную запись Google , где пользователи могут управлять своей связанной учетной записью.

  7. Возможность смены учетной записи пользователя. Предложите пользователям способ переключения их учетных записей. Это особенно полезно, если пользователи склонны иметь несколько учетных записей.

    • Если пользователю необходимо закрыть экран согласия для переключения учетных записей, отправьте в Google устранимую ошибку, чтобы пользователь мог войти в нужную учетную запись с помощью привязки OAuth и неявного потока.
  8. Включите свой логотип. Отобразите логотип вашей компании на экране согласия. Используйте свои рекомендации по стилю, чтобы разместить свой логотип. Если вы хотите также отобразить логотип Google, см. раздел Логотипы и товарные знаки .

Create the project

To create your project to use account linking:

  1. Go to the Google API Console.
  2. Нажмите Создать проект .
  3. Введите имя или примите сгенерированное предложение.
  4. Подтвердите или отредактируйте оставшиеся поля.
  5. Нажмите Создать .

Для просмотра идентификатора вашего проекта:

  1. Go to the Google API Console.
  2. Найдите свой проект в таблице на целевой странице. Идентификатор проекта отображается в столбце идентификаторов .

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.

Внедрите свой сервер OAuth

An OAuth 2.0 server implementation of the authorization code flow consists of two endpoints, which your service makes available by HTTPS. The first endpoint is the authorization endpoint, which is responsible for finding or obtaining consent from users for data access. The authorization endpoint presents a sign-in UI to your users that aren't already signed in and records consent to the requested access. The second endpoint is the token exchange endpoint, which is used to obtain encrypted strings, called tokens, that authorize a user to access your service.

When a Google application needs to call one of your service's APIs, Google uses these endpoints together to get permission from your users to call these APIs on their behalf.

An OAuth 2.0 authorization code flow session initiated by Google has the following flow:

  1. Google opens your authorization endpoint in the user's browser. If the flow started on a voice-only device for an Action, Google transfers the execution to a phone.
  2. The user signs in, if not signed in already, and grants Google permission to access their data with your API, if they haven't already granted permission.
  3. Your service creates an authorization code and returns it to Google. To do so, redirect the user's browser back to Google with the authorization code attached to the request.
  4. Google sends the authorization code to your token exchange endpoint, which verifies the authenticity of the code and returns an access token and a refresh token. The access token is a short-lived token that your service accepts as credentials to access APIs. The refresh token is a long-lived token that Google can store and use to acquire new access tokens when they expire.
  5. After the user has completed the account linking flow, every subsequent request sent from Google contains an access token.

Handle authorization requests

When you need to perform account linking using the OAuth 2.0 authorization code flow, Google sends the user to your authorization endpoint with a request that includes the following parameters:

Authorization endpoint parameters
client_id The Client ID you assigned to Google.
redirect_uri The URL to which you send the response to this request.
state A bookkeeping value that is passed back to Google unchanged in the redirect URI.
scope Optional: A space-delimited set of scope strings that specify the data Google is requesting authorization for.
response_type The type of value to return in the response. For the OAuth 2.0 authorization code flow, the response type is always code.
user_locale The Google Account language setting in RFC5646 format, used to localize your content in the user's preferred language.

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

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

For your authorization endpoint to handle sign-in requests, do the following steps:

  1. Verify that the client_id matches the Client ID you assigned to Google, and that the redirect_uri matches the redirect URL provided by Google for your service. These checks are important to prevent granting access to unintended or misconfigured client apps. If you support multiple OAuth 2.0 flows, also confirm that the response_type is code.
  2. Check if the user is signed in to your service. If the user isn't signed in, complete your service's sign-in or sign-up flow.
  3. Generate an authorization code for Google to use to access your API. The authorization code can be any string value, but it must uniquely represent the user, the client the token is for, and the code's expiration time, and it must not be guessable. You typically issue authorization codes that expire after approximately 10 minutes.
  4. Confirm that the URL specified by the redirect_uri parameter has the following form:
      https://oauth-redirect.googleusercontent.com/r/YOUR_PROJECT_ID
      https://oauth-redirect-sandbox.googleusercontent.com/r/YOUR_PROJECT_ID
      
  5. Redirect the user's browser to the URL specified by the redirect_uri parameter. Include the authorization code you just generated and the original, unmodified state value when you redirect by appending the code and state parameters. The following is an example of the resulting URL:
    https://oauth-redirect.googleusercontent.com/r/YOUR_PROJECT_ID?code=AUTHORIZATION_CODE&state=STATE_STRING

Handle token exchange requests

Your service's token exchange endpoint is responsible for two kinds of token exchanges:

  • Exchange authorization codes for access tokens and refresh tokens
  • Exchange refresh tokens for access tokens

Token exchange requests include the following parameters:

Token exchange endpoint parameters
client_id A string that identifies the request origin as Google. This string must be registered within your system as Google's unique identifier.
client_secret A secret string that you registered with Google for your service.
grant_type The type of token being exchanged. It's either authorization_code or refresh_token.
code When grant_type=authorization_code, this parameter is the code Google received from either your sign-in or token exchange endpoint.
redirect_uri When grant_type=authorization_code, this parameter is the URL used in the initial authorization request.
refresh_token When grant_type=refresh_token, this parameter is the refresh token Google received from your token exchange endpoint.
Exchange authorization codes for access tokens and refresh tokens

After the user signs in and your authorization endpoint returns a short-lived authorization code to Google, Google sends a request to your token exchange endpoint to exchange the authorization code for an access token and a refresh token.

For these requests, the value of grant_type is authorization_code, and the value of code is the value of the authorization code you previously granted to Google. The following is an example of a request to exchange an authorization code for an access token and a refresh token:

POST /token HTTP/1.1
Host: oauth2.example.com
Content-Type: application/x-www-form-urlencoded

client_id=GOOGLE_CLIENT_ID&client_secret=GOOGLE_CLIENT_SECRET&grant_type=authorization_code&code=AUTHORIZATION_CODE&redirect_uri=REDIRECT_URI

To exchange authorization codes for an access token and a refresh token, your token exchange endpoint responds to POST requests by executing the following steps:

  1. Verify that the client_id identifies the request origin as an authorized origin, and that the client_secret matches the expected value.
  2. Verify that the authorization code is valid and not expired, and that the client ID specified in the request matches the client ID associated with the authorization code.
  3. Confirm that the URL specified by the redirect_uri parameter is identical to the value used in the initial authorization request.
  4. If you can't verify all of the above criteria, return an HTTP 400 Bad Request error with {"error": "invalid_grant"} as the body.
  5. Otherwise, use the user ID from the authorization code to generate a refresh token and an access token. These tokens can be any string value, but they must uniquely represent the user and the client the token is for, and they must not be guessable. For access tokens, also record the expiration time of the token, which is typically an hour after you issue the token. Refresh tokens don't expire.
  6. Return the following JSON object in the body of the HTTPS response:
    {
    "token_type": "Bearer",
    "access_token": "ACCESS_TOKEN",
    "refresh_token": "REFRESH_TOKEN",
    "expires_in": SECONDS_TO_EXPIRATION
    }
    

Google stores the access token and the refresh token for the user and records the expiration of the access token. When the access token expires, Google uses the refresh token to get a new access token from your token exchange endpoint.

Exchange refresh tokens for access tokens

When an access token expires, Google sends a request to your token exchange endpoint to exchange a refresh token for a new access token.

For these requests, the value of grant_type is refresh_token, and the value of refresh_token is the value of the refresh token you previously granted to Google. The following is an example of a request to exchange a refresh token for an access token:

POST /token HTTP/1.1
Host: oauth2.example.com
Content-Type: application/x-www-form-urlencoded

client_id=GOOGLE_CLIENT_ID&client_secret=GOOGLE_CLIENT_SECRET&grant_type=refresh_token&refresh_token=REFRESH_TOKEN

To exchange a refresh token for an access token, your token exchange endpoint responds to POST requests by executing the following steps:

  1. Verify that the client_id identifies the request origin as Google, and that the client_secret matches the expected value.
  2. Verify that the refresh token is valid, and that the client ID specified in the request matches the client ID associated with the refresh token.
  3. If you can't verify all of the above criteria, return an HTTP 400 Bad Request error with {"error": "invalid_grant"} as the body.
  4. Otherwise, use the user ID from the refresh token to generate an access token. These tokens can be any string value, but they must uniquely represent the user and the client the token is for, and they must not be guessable. For access tokens, also record the expiration time of the token, typically an hour after you issue the token.
  5. Return the following JSON object in the body of the HTTPS response:
    {
    "token_type": "Bearer",
    "access_token": "ACCESS_TOKEN",
    "expires_in": SECONDS_TO_EXPIRATION
    }
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:

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.

Проверка вашей реализации

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.