帳戶連結使用業界標準 OAuth 2.0 隱含與授權碼流程。您的服務必須支援符合 OAuth 2.0 規定的授權和憑證交換端點。
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:
- 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.
- 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.
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.
![This figure shows the steps for a user to link their Google account
to your authentication system. The first screenshot shows
user-initiated linking from your platform. The second image shows
user sign-in to Google, while the third shows the user consent and
confirmation for linking their Google account with your app. The
final screenshot shows a successfully linked user account in the
Google app.](https://developers-dot-devsite-v2-prod.appspot.com/static/identity/images/oauth-linking-flow.png?authuser=2&hl=zh-tw)
Requirements
- 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:
Display Google's Privacy Policy. Include a link to Google’s Privacy Policy on the consent screen.
Data to be shared. Use clear and concise language to tell the user what data of theirs Google requires and why.
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.
Ability to cancel. Provide a way for users to go back or cancel, if they choose not to link.
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.
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.
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.
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.
![This figure shows example user sign in and consent screens with
call-outs to the individual requirements and recommendations to
follow when you design a user sign in and consent screen.](https://developers-dot-devsite-v2-prod.appspot.com/static/identity/images/oauth-linking-consent.png?authuser=2&hl=zh-tw)
建立專案
如要建立專案以使用帳戶連結功能,請按照下列步驟操作:
- Go to the Google API Console.
- 單擊創建項目 。
- 輸入名稱或接受生成的建議。
- 確認或編輯所有剩餘字段。
- 點擊創建 。
要查看您的項目ID:
- Go to the Google API Console.
- 在登錄頁面的表格中找到您的項目。項目ID出現在ID列中。
設定 OAuth 同意畫面
Google 帳戶連結程序包含同意畫面,可告知使用者應用程式要求存取資料、要求的資料類型和適用的條款。您必須先設定 OAuth 同意畫面,才能產生 Google API 用戶端 ID。
- 開啟 Google API 控制台的「OAuth 同意畫面」頁面。
- 如果出現提示,請選取您剛建立的專案。
在「OAuth 同意畫面」頁面上,填寫表單,然後按一下「Save」按鈕。
Application name (應用程式名稱):要求同意的應用程式名稱。名稱必須如實反映您的應用程式,並與使用者在其他地方看到的應用程式名稱一致。應用程式名稱會顯示在「帳戶連結同意」畫面中。
應用程式標誌:可協助使用者識別您應用程式的圖片。這個標誌會顯示在帳戶連結同意畫面和帳戶設定中
支援電子郵件:方便使用者與您聯絡,詢問同意聲明問題。
Google API 的範圍:「範圍」可讓應用程式存取使用者的私人 Google 資料。就 Google 帳戶連結的情況而言,預設範圍 (電子郵件、設定檔、openid) 就已足夠,您不需要新增任何敏感範圍。一般而言,最佳做法是逐步要求範圍,且在需要時而非預先存取權。瞭解詳情。
授權網域:為了保護您和您的使用者,Google 僅允許透過 OAuth 進行驗證的應用程式使用授權網域。您的應用程式連結必須託管於授權網域。瞭解詳情。
應用程式首頁連結:應用程式的首頁。必須由授權網域代管。
應用程式隱私權政策連結:會顯示在 Google 帳戶連結同意畫面中。必須由授權網域代管。
應用程式服務條款連結 (選用):必須由授權網域代管。
圖 1. 虛構應用程式的 Google 帳戶連結同意畫面:Tunery
查看「驗證狀態」。若您的申請需要驗證,請按一下「提交驗證申請」按鈕,提交驗證申請。詳情請參閱「OAuth 驗證規定」一文。
實作 OAuth 伺服器
To support the OAuth 2.0 implicit flow, your service makes an authorization endpoint available by HTTPS. This endpoint is responsible for authentication and 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.
When a Google application needs to call one of your service's authorized APIs, Google uses this endpoint to get permission from your users to call these APIs on their behalf.
A typical OAuth 2.0 implicit flow session initiated by Google has the following flow:
- Google opens your authorization endpoint in the user's browser. 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.
- Your service creates an access token and returns it to Google. To do so, redirect the user's browser back to Google with the access token attached to the request.
- Google calls your service's APIs and attaches the access token with each request. Your service verifies that the access token grants Google authorization to access the API and then completes the API call.
Handle authorization requests
When a Google application needs to perform account linking via an OAuth 2.0 implicit 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. |
response_type |
The type of value to return in the response. For the OAuth 2.0 implicit
flow, the response type is always token . |
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&response_type=token&user_locale=LOCALE
For your authorization endpoint to handle sign-in requests, do the following steps:
Verify the
client_id
andredirect_uri
values to prevent granting access to unintended or misconfigured client apps:- Confirm that the
client_id
matches the client ID you assigned to Google. - 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
- Confirm that the
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.
Generate an access token for Google to use to access your API. The access token can be any string value, but it must uniquely represent the user and the client the token is for and must not be guessable.
Send an HTTP response that redirects the user's browser to the URL specified by the
redirect_uri
parameter. Include all of the following parameters in the URL fragment:access_token
: The access token you just generatedtoken_type
: The stringbearer
state
: The unmodified state value from the original request
The following is an example of the resulting URL:
https://oauth-redirect.googleusercontent.com/r/YOUR_PROJECT_ID#access_token=ACCESS_TOKEN&token_type=bearer&state=STATE_STRING
Google's OAuth 2.0 redirect handler receives the access token and confirms
that the state
value hasn't changed. After Google has obtained an
access token for your service, Google attaches the token to subsequent calls
to your service APIs.
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:
- Extract access token from the Authorization header and return information for the user associated with the access token.
- 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. 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.
驗證實作
You can validate your implementation by using the OAuth 2.0 Playground tool.
In the tool, do the following steps:
- Click Configuration to open the OAuth 2.0 Configuration window.
- In the OAuth flow field, select Client-side.
- In the OAuth Endpoints field, select Custom.
- Specify your OAuth 2.0 endpoint and the client ID you assigned to Google in the corresponding fields.
- 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.
- 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:
- Click the Sign-in with Google button.
- Choose the account you'd like to link.
- Enter the service ID.
- Optionally enter one or more scopes that you will request access for.
- Click Start Demo.
- When prompted, confirm that you may consent and deny the linking request.
- Confirm that you are redirected to your platform.