通过 OAuth 和“使用 Google 账号登录”简化关联流程

概览

基于 OAuth 的“使用 Google 账号登录”简化版关联在 OAuth 关联的基础上添加了“使用 Google 账号登录”。这样一来，Google 用户便可顺畅地关联账号，同时还能创建账号，让用户可以使用自己的 Google 账号在您的服务中创建新账号。

如需使用 OAuth 和“使用 Google 账号登录”功能执行账号关联，请按以下常规步骤操作：

  1. 首先，征求用户同意以访问其 Google 个人资料。
  2. 使用用户个人资料中的信息检查用户账号是否存在。
  3. 对于现有用户，请关联账号。
  4. 如果您在身份验证系统中找不到与 Google 用户匹配的用户，请验证从 Google 收到的 ID 令牌。然后，您可以根据 ID 令牌中包含的个人资料信息创建用户。
此图显示了用户使用简化的关联流程关联其 Google 账号的步骤。第一张屏幕截图显示了用户如何选择您的应用以进行关联。第二个屏幕截图可让用户确认他们是否在您的服务中拥有现有账号。第三张屏幕截图显示了用户可以选择要关联的 Google 账号。第四张屏幕截图显示了将用户的 Google 账号与您的应用相关联的确认信息。第五张屏幕截图显示了 Google 应用中成功关联的用户账号。
在用户手机上通过精简关联功能关联账号

图 1. 在用户手机上使用精简的关联方式进行账号关联

简化的关联：OAuth +“使用 Google 账号登录”流程

以下序列图详细说明了用户、Google 和您的令牌交换端点之间针对简化关联的互动。

用户 Google 应用 / 服务器 您的令牌 交换端点 您的 API 1. 用户发起关联 2. 请求使用 Google 账号登录 3. 使用 Google 账号登录 4. 检查 intent (JWT 断言) 5. account_found：true/false 如果找到账号： 6. 获取 intent 如果未找到账号： 6. 创建 intent 7. access_token、refresh_token 8. 存储用户令牌 9. 访问用户资源
图 2. 简化版关联流程中的事件序列。

角色和职责

下表定义了简化版关联流程中各个参与者的角色和职责。

执行者 / 组件 GAL 角色 职责
Google 应用 / 服务器 OAuth 客户端 获取用户对“使用 Google 账号登录”的同意情况，将身份断言 (JWT) 传递给您的服务器，并安全地存储生成的令牌。
您的令牌交换端点 身份提供方 / 授权服务器 验证身份断言，检查是否存在现有账号，处理账号关联 intent（check、get、create），并根据请求的 intent 签发令牌。
您的服务 API 资源服务器 在提供有效的访问令牌时，提供对用户数据的访问权限。

简化版关联的要求

实现 OAuth 服务器

您的令牌交换端点必须支持 check、create、get intent。请按以下步骤操作，完成账号关联流程并了解何时使用不同的意图：

  1. 用户在您的身份验证系统中是否有账号？（用户通过选择“是”或“否”来决定）
    1. 是：用户是否使用其 Google 账号关联的电子邮件地址登录您的平台？（用户通过选择“是”或“否”来决定）
      1. 是：用户在您的身份验证系统中是否有匹配的账号？ （check intent被调用以确认）
        1. 是：调用 get intent，如果获取 intent 成功返回，则关联账号。
        2. 否：创建新账号？（用户通过选择“是”或“否”来决定）
          1. 是： 如果创建 intent 成功返回，则会调用 create intent 并关联账号。
          2. 否：系统会触发 OAuth 关联流程，将用户引导至浏览器，并为用户提供与不同电子邮件地址关联的选项。
      2. 否：系统会触发 OAuth 关联流程，将用户定向到其浏览器，并为用户提供与不同电子邮件地址关联的选项。
    2. 否：用户在您的身份验证系统中是否有匹配的账号？ （调用 check intent 以确认）
      1. 是：调用 get intent，如果获取 intent 成功返回，则关联账号。
      2. 否：如果创建 intent 成功返回，则会调用 create intent 并关联账号。

Check for an existing user account (check intent)

After the user gives consent to access their Google profile, Google sends a request that contains a signed assertion of the Google user's identity. The assertion contains information that includes the user's Google Account ID, name, and email address. The token exchange endpoint configured for your project handles that request.

If the corresponding Google account is already present in your authentication system, your token exchange endpoint responds with account_found=true. If the Google account doesn't match an existing user, your token exchange endpoint returns an HTTP 404 Not Found error with account_found=false.

The request has the following form:

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

grant_type=urn:ietf:params:oauth:grant-type:jwt-bearer&intent=check&assertion=JWT&scope=SCOPES&client_id=GOOGLE_CLIENT_ID&client_secret=GOOGLE_CLIENT_SECRET

Your token exchange endpoint must be able to handle the following parameters:

Token endpoint parameters
intent For these requests, the value of this parameter is check.
grant_type The type of token being exchanged. For these requests, this parameter has the value urn:ietf:params:oauth:grant-type:jwt-bearer.
assertion A JSON Web Token (JWT) that provides a signed assertion of the Google user's identity. The JWT contains information that includes the user's Google Account ID, name, and email address.
client_id The client ID you assigned to Google.
client_secret The client secret you assigned to Google.

To respond to the check intent requests, your token exchange endpoint must perform the following steps:

  • Validate and decode the JWT assertion.
  • Check if the Google account is already present in your authentication system.
Validate and decode the JWT assertion

You can validate and decode the JWT assertion by using a JWT-decoding library for your language. Use Google's public keys, available in JWK or PEM formats, to verify the token's signature.

When decoded, the JWT assertion looks like the following example: 

{
  "sub": "1234567890",      // The unique ID of the user's Google Account
  "iss": "https://accounts.google.com",        // The assertion's issuer
  "aud": "123-abc.apps.googleusercontent.com", // Your server's client ID
  "iat": 233366400,         // Unix timestamp of the assertion's creation time
  "exp": 233370000,         // Unix timestamp of the assertion's expiration time
  "name": "Jan Jansen",
  "given_name": "Jan",
  "family_name": "Jansen",
  "email": "jan@gmail.com", // If present, the user's email address
  "email_verified": true,   // true, if Google has verified the email address
  "hd": "example.com",      // If present, the host domain of the user's GSuite email address
                            // If present, a URL to user's profile picture
  "picture": "https://lh3.googleusercontent.com/a-/AOh14GjlTnZKHAeb94A-FmEbwZv7uJD986VOF1mJGb2YYQ",
  "locale": "en_US"         // User's locale, from browser or phone settings
}

In addition to verifying the token's signature, verify that the assertion's issuer (iss field) is https://accounts.google.com, that the audience (aud field) is your assigned client ID, and that the token has not expired (exp field).

Using the email, email_verified and hd fields you can determine if Google hosts and is authoritative for an email address. In cases where Google is authoritative the user is currently known to be the legitimate account owner and you may skip password or other challenges methods. Otherwise, these methods can be used to verify the account prior to linking.

Cases where Google is authoritative:

  • email has a @gmail.com suffix, this is a Gmail account.
  • email_verified is true and hd is set, this is a G Suite account.

Users may register for Google Accounts without using Gmail or G Suite. When email does not contain a @gmail.com suffix and hd is absent Google is not authoritative and password or other challenge methods are recommended to verify the user. email_verified can also be true as Google initially verified the user when the Google account was created, however ownership of the third party email account may have since changed.

Check if the Google account is already present in your authentication system

Check whether either of the following conditions are true:

  • The Google Account ID, found in the assertion's sub field, is in your user database.
  • The email address in the assertion matches a user in your user database.

If either condition is true, the user has already signed up. In that case, return a response like the following:

HTTP/1.1 200 Success
Content-Type: application/json;charset=UTF-8

{
  "account_found":"true",
}

If neither the Google Account ID nor the email address specified in the assertion matches a user in your database, the user hasn't signed up yet. In this case, your token exchange endpoint needs to reply with a HTTP 404 error that specifies "account_found": "false", as in the following example:

HTTP/1.1 404 Not found
Content-Type: application/json;charset=UTF-8

{
  "account_found":"false",
}

Handle automatic linking (get intent)

After the user gives consent to access their Google profile, Google sends a request that contains a signed assertion of the Google user's identity. The assertion contains information that includes the user's Google Account ID, name, and email address. The token exchange endpoint configured for your project handles that request.

If the corresponding Google Account is already present in your authentication system, your token exchange endpoint returns a token for the user. If the Google Account doesn't match an existing user, your token exchange endpoint returns a linking_error error and optional login_hint.

The request has the following form:

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

grant_type=urn:ietf:params:oauth:grant-type:jwt-bearer&intent=get&assertion=JWT&scope=SCOPES&client_id=GOOGLE_CLIENT_ID&client_secret=GOOGLE_CLIENT_SECRET

Your token exchange endpoint must be able to handle the following parameters:

Token endpoint parameters
intent For these requests, the value of this parameter is get.
grant_type The type of token being exchanged. For these requests, this parameter has the value urn:ietf:params:oauth:grant-type:jwt-bearer.
assertion A JSON Web Token (JWT) that provides a signed assertion of the Google user's identity. The JWT contains information that includes the user's Google Account ID, name, and email address.
scope Optional: Any scopes that you've configured Google to request from users.
client_id The client ID you assigned to Google.
client_secret The client secret you assigned to Google.

To respond to the get intent requests, your token exchange endpoint must perform the following steps:

  • Validate and decode the JWT assertion.
  • Check if the Google account is already present in your authentication system.
Validate and decode the JWT assertion

You can validate and decode the JWT assertion by using a JWT-decoding library for your language. Use Google's public keys, available in JWK or PEM formats, to verify the token's signature.

When decoded, the JWT assertion looks like the following example: 

{
  "sub": "1234567890",      // The unique ID of the user's Google Account
  "iss": "https://accounts.google.com",        // The assertion's issuer
  "aud": "123-abc.apps.googleusercontent.com", // Your server's client ID
  "iat": 233366400,         // Unix timestamp of the assertion's creation time
  "exp": 233370000,         // Unix timestamp of the assertion's expiration time
  "name": "Jan Jansen",
  "given_name": "Jan",
  "family_name": "Jansen",
  "email": "jan@gmail.com", // If present, the user's email address
  "email_verified": true,   // true, if Google has verified the email address
  "hd": "example.com",      // If present, the host domain of the user's GSuite email address
                            // If present, a URL to user's profile picture
  "picture": "https://lh3.googleusercontent.com/a-/AOh14GjlTnZKHAeb94A-FmEbwZv7uJD986VOF1mJGb2YYQ",
  "locale": "en_US"         // User's locale, from browser or phone settings
}

In addition to verifying the token's signature, verify that the assertion's issuer (iss field) is https://accounts.google.com, that the audience (aud field) is your assigned client ID, and that the token has not expired (exp field).

Using the email, email_verified and hd fields you can determine if Google hosts and is authoritative for an email address. In cases where Google is authoritative the user is currently known to be the legitimate account owner and you may skip password or other challenges methods. Otherwise, these methods can be used to verify the account prior to linking.

Cases where Google is authoritative:

  • email has a @gmail.com suffix, this is a Gmail account.
  • email_verified is true and hd is set, this is a G Suite account.

Users may register for Google Accounts without using Gmail or G Suite. When email does not contain a @gmail.com suffix and hd is absent Google is not authoritative and password or other challenge methods are recommended to verify the user. email_verified can also be true as Google initially verified the user when the Google account was created, however ownership of the third party email account may have since changed.

Check if the Google account is already present in your authentication system

Check whether either of the following conditions are true:

  • The Google Account ID, found in the assertion's sub field, is in your user database.
  • The email address in the assertion matches a user in your user database.

If an account is found for the user, issue an access token and return the values in a JSON object in the body of your HTTPS response, like in the following example: 

{
  "token_type": "Bearer",
  "access_token": "ACCESS_TOKEN",
  "refresh_token": "REFRESH_TOKEN",
  "expires_in": SECONDS_TO_EXPIRATION
}

In some cases, account linking based on ID token might fail for the user. If it does so for any reason, your token exchange endpoint needs to reply with a HTTP 401 error that specifies error=linking_error, as the following example shows:

HTTP/1.1 401 Unauthorized
Content-Type: application/json;charset=UTF-8

{
  "error":"linking_error",
  "login_hint":"foo@bar.com"
}

When Google receives a 401 error response with linking_error, Google sends the user to your authorization endpoint with login_hint as a parameter. The user completes account linking using the OAuth linking flow in their browser.

使用“使用 Google 账号登录”处理账号创建（创建 intent）

当用户需要在您的服务中创建账号时，Google 会向您的令牌交换端点发出请求，其中指定了 intent=create。

该请求采用以下形式：

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

response_type=token&grant_type=urn:ietf:params:oauth:grant-type:jwt-bearer&scope=SCOPES&intent=create&assertion=JWT&client_id=GOOGLE_CLIENT_ID&client_secret=GOOGLE_CLIENT_SECRET

您的令牌交换端点必须能够处理以下参数：

令牌端点参数
intent 对于这些请求，此参数的值为 create。
grant_type 要交换的令牌的类型。对于这些请求，此 参数的值为 urn:ietf:params:oauth:grant-type:jwt-bearer。
assertion JSON 网络令牌 (JWT)，用于提供 Google 用户身份的签名断言。JWT 包含的信息包括用户的 Google 账号 ID、姓名和电子邮件地址。
client_id 您分配给 Google 的客户端 ID。
client_secret 您分配给 Google 的客户端密钥。

assertion 参数中的 JWT 包含用户的 Google 账号 ID、姓名和电子邮件地址，您可以使用这些信息在您的服务中创建新账号。

如需响应 create intent 请求，您的令牌交换端点必须执行以下步骤：

  • 验证 JWT 断言并对其进行解码。
  • 验证用户信息并创建新账号。
Validate and decode the JWT assertion

You can validate and decode the JWT assertion by using a JWT-decoding library for your language. Use Google's public keys, available in JWK or PEM formats, to verify the token's signature.

When decoded, the JWT assertion looks like the following example: 

{
  "sub": "1234567890",      // The unique ID of the user's Google Account
  "iss": "https://accounts.google.com",        // The assertion's issuer
  "aud": "123-abc.apps.googleusercontent.com", // Your server's client ID
  "iat": 233366400,         // Unix timestamp of the assertion's creation time
  "exp": 233370000,         // Unix timestamp of the assertion's expiration time
  "name": "Jan Jansen",
  "given_name": "Jan",
  "family_name": "Jansen",
  "email": "jan@gmail.com", // If present, the user's email address
  "email_verified": true,   // true, if Google has verified the email address
  "hd": "example.com",      // If present, the host domain of the user's GSuite email address
                            // If present, a URL to user's profile picture
  "picture": "https://lh3.googleusercontent.com/a-/AOh14GjlTnZKHAeb94A-FmEbwZv7uJD986VOF1mJGb2YYQ",
  "locale": "en_US"         // User's locale, from browser or phone settings
}

In addition to verifying the token's signature, verify that the assertion's issuer (iss field) is https://accounts.google.com, that the audience (aud field) is your assigned client ID, and that the token has not expired (exp field).

Using the email, email_verified and hd fields you can determine if Google hosts and is authoritative for an email address. In cases where Google is authoritative the user is currently known to be the legitimate account owner and you may skip password or other challenges methods. Otherwise, these methods can be used to verify the account prior to linking.

Cases where Google is authoritative:

  • email has a @gmail.com suffix, this is a Gmail account.
  • email_verified is true and hd is set, this is a G Suite account.

Users may register for Google Accounts without using Gmail or G Suite. When email does not contain a @gmail.com suffix and hd is absent Google is not authoritative and password or other challenge methods are recommended to verify the user. email_verified can also be true as Google initially verified the user when the Google account was created, however ownership of the third party email account may have since changed.

验证用户信息并创建新账号

检查是否满足以下任一条件：

  • 断言的 sub 字段中找到的 Google 账号 ID 位于您的用户数据库中。
  • 断言中的电子邮件地址与用户数据库中的用户匹配。

如果满足任一条件，请提示用户将其现有账号与其 Google 账号相关联。为此，请使用 HTTP 401 错误响应请求，该错误指定了 error=linking_error 并将用户的电子邮件地址作为 login_hint。以下是示例响应：

HTTP/1.1 401 Unauthorized
Content-Type: application/json;charset=UTF-8

{
  "error":"linking_error",
  "login_hint":"foo@bar.com"
}

当 Google 收到包含 linking_error 的 401 错误响应时，Google 会将用户发送到您的授权端点，并将 login_hint 作为参数。用户在其浏览器中使用 OAuth 关联流程完成账号关联。

如果这两个条件都不满足，请使用 JWT 中提供的信息创建新的用户账号。新账号通常没有设置密码。建议您将“使用 Google 账号登录”添加到其他平台，以便用户可以在应用的所有界面上使用 Google 账号登录。或者，您也可以通过电子邮件向用户发送一个链接，该链接会启动密码恢复流程，让用户设置密码以便在其他平台上登录。

创建完成后，请发出访问令牌 ，并在 HTTPS 响应正文中的 JSON 对象内返回这些值，如以下示例所示：

{
  "token_type": "Bearer",
  "access_token": "ACCESS_TOKEN",
  "refresh_token": "REFRESH_TOKEN",
  "expires_in": SECONDS_TO_EXPIRATION
}

获取 Google API 客户端 ID

在账号关联注册过程中，您需要提供 Google API 客户端 ID。使用您在完成 OAuth 关联步骤时创建的项目获取 API 客户端 ID。为此，请完成以下步骤：

  1. 前往“客户”页面。

  2. 创建或选择 Google APIs 项目。

    如果您的项目没有 Web 应用类型的客户端 ID，请点击创建客户端进行创建。请务必在已获授权的 JavaScript 来源框中添加您网站的域名。在执行本地测试或开发时，您必须将 http://localhost 和 http://localhost:<port_number> 都添加到已获授权的 JavaScript 来源字段中。

验证您的实现效果

您可以使用 OAuth 2.0 Playground 工具验证您的实现。

在该工具中，执行以下步骤：

  1. 点击配置 以打开“OAuth 2.0 配置”窗口。
  2. 在 OAuth flow（OAuth 流程）字段中，选择 Client-side（客户端）。
  3. 在 OAuth Endpoints 字段中，选择 Custom。
  4. 在相应字段中指定您的 OAuth 2.0 端点以及您分配给 Google 的客户端 ID。
  5. 在第 1 步部分中，请勿选择任何 Google 范围。请将此字段留空，或输入适用于您服务器的范围（如果您不使用 OAuth 范围，则输入任意字符串）。完成后，点击 Authorize APIs。
  6. 在第 2 步和第 3 步部分中，完成 OAuth 2.0 流程，并验证每个步骤是否按预期运行。

您可以使用 Google 账号关联演示工具验证您的实现。

在该工具中，执行以下步骤：

  1. 点击使用 Google 账号登录按钮。
  2. 选择您要关联的账号。
  3. 输入服务 ID。
  4. （可选）输入您将请求访问的一个或多个范围。
  5. 点击开始演示。
  6. 当系统提示时，请确认您可以同意或拒绝关联请求。
  7. 确认您已重定向到相应平台。