使用后端服务器进行身份验证

如果您在与后端服务器通信的应用或网站上使用 Google 登录功能,则可能需要识别该服务器上当前已登录的用户。为了安全地执行此操作,请在用户成功登录后,使用 HTTPS 将该用户的 ID 令牌发送到您的服务器。然后,在服务器上验证 ID 令牌的完整性,并使用令牌中包含的用户信息来建立会话或创建新帐号。

将 ID 令牌发送到您的服务器

在用户成功登录后,获取其 ID 令牌:

Swift

GIDSignIn.sharedInstance.signIn(withPresenting: self) { signInResult, error in
    guard error == nil else { return }
    guard let signInResult = signInResult else { return }

    signInResult.user.refreshTokensIfNeeded { user, error in
        guard error == nil else { return }
        guard let user = user else { return }

        let idToken = user.idToken
        // Send ID token to backend (example below).
    }
}

Objective-C

[GIDSignIn.sharedInstance signInWithPresentingViewController:self
                                              completion:^(GIDSignInResult * _Nullable signInResult,
                                                           NSError * _Nullable error) {
      if (error) { return; }
      if (signInResult == nil) { return; }

      [signInResult.user refreshTokensIfNeededWithCompletion:^(GIDGoogleUser * _Nullable user,
                                                               NSError * _Nullable error) {
          if (error) { return; }
          if (user == nil) { return; }

          NSString *idToken = user.idToken;
          // Send ID token to backend (example below).
      }];
}];

然后,使用 HTTPS POST 请求将 ID 令牌发送到您的服务器:

Swift

func tokenSignInExample(idToken: String) {
    guard let authData = try? JSONEncoder().encode(["idToken": idToken]) else {
        return
    }
    let url = URL(string: "https://yourbackend.example.com/tokensignin")!
    var request = URLRequest(url: url)
    request.httpMethod = "POST"
    request.setValue("application/json", forHTTPHeaderField: "Content-Type")

    let task = URLSession.shared.uploadTask(with: request, from: authData) { data, response, error in
        // Handle response from your backend.
    }
    task.resume()
}

Objective-C

NSString *signinEndpoint = @"https://yourbackend.example.com/tokensignin";
NSDictionary *params = @{@"idtoken": idToken};

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:signinEndpoint];
[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
[request setHTTPMethod:@"POST"];
[request setHTTPBody:[self httpBodyForParamsDictionary:params]];

NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[NSURLConnection sendAsynchronousRequest:request
                                   queue:queue
                       completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
                         if (error) {
                           NSLog(@"Error: %@", error.localizedDescription);
                         } else {
                           NSLog(@"Signed in as %@", data.bytes);
                         }
                       }];

验证 ID 令牌的完整性

通过 HTTPS POST 收到 ID 令牌后,您必须验证令牌的完整性。

To verify that the token is valid, ensure that the following criteria are satisfied:

  • The ID token is properly signed by Google. Use Google's public keys (available in JWK or PEM format) to verify the token's signature. These keys are regularly rotated; examine the Cache-Control header in the response to determine when you should retrieve them again.
  • The value of aud in the ID token is equal to one of your app's client IDs. This check is necessary to prevent ID tokens issued to a malicious app being used to access data about the same user on your app's backend server.
  • The value of iss in the ID token is equal to accounts.google.com or https://accounts.google.com.
  • The expiry time (exp) of the ID token has not passed.
  • If you need to validate that the ID token represents a Google Workspace or Cloud organization account, you can check the hd claim, which indicates the hosted domain of the user. This must be used when restricting access to a resource to only members of certain domains. The absence of this claim indicates that the account does not belong to a Google hosted domain.

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

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.

Rather than writing your own code to perform these verification steps, we strongly recommend using a Google API client library for your platform, or a general-purpose JWT library. For development and debugging, you can call our tokeninfo validation endpoint.

使用 Google API 客户端库

使用某个 Google API 客户端库(例如 JavaNode.jsPHPPython) 是在生产环境中验证 Google ID 令牌的推荐方法。

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Java

要在 Java 中验证 ID 令牌,请使用 GoogleIdTokenVerifier 对象。例如:

import com.google.api.client.googleapis.auth.oauth2.GoogleIdToken;
import com.google.api.client.googleapis.auth.oauth2.GoogleIdToken.Payload;
import com.google.api.client.googleapis.auth.oauth2.GoogleIdTokenVerifier;

...

GoogleIdTokenVerifier verifier = new GoogleIdTokenVerifier.Builder(transport, jsonFactory)
    // Specify the CLIENT_ID of the app that accesses the backend:
    .setAudience(Collections.singletonList(CLIENT_ID))
    // Or, if multiple clients access the backend:
    //.setAudience(Arrays.asList(CLIENT_ID_1, CLIENT_ID_2, CLIENT_ID_3))
    .build();

// (Receive idTokenString by HTTPS POST)

GoogleIdToken idToken = verifier.verify(idTokenString);
if (idToken != null) {
  Payload payload = idToken.getPayload();

  // Print user identifier
  String userId = payload.getSubject();
  System.out.println("User ID: " + userId);

  // Get profile information from payload
  String email = payload.getEmail();
  boolean emailVerified = Boolean.valueOf(payload.getEmailVerified());
  String name = (String) payload.get("name");
  String pictureUrl = (String) payload.get("picture");
  String locale = (String) payload.get("locale");
  String familyName = (String) payload.get("family_name");
  String givenName = (String) payload.get("given_name");

  // Use or store profile information
  // ...

} else {
  System.out.println("Invalid ID token.");
}

GoogleIdTokenVerifier.verify() 方法验证 JWT 签名、aud 声明、iss 声明以及 exp 项版权主张。

如果您需要验证 ID 令牌是否代表 Google Workspace 或 Cloud 组织账号,您可以通过检查域名来验证 hd 所有权声明 由 Payload.getHostedDomain() 方法返回。该 email 声明不足以保证账号是由网域管理 或组织。

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Node.js

要在 Node.js 中验证 ID 令牌,请使用适用于 Node.js 的 Google Auth 库。 安装该库:

npm install google-auth-library --save
然后,调用 verifyIdToken() 函数。例如:

const {OAuth2Client} = require('google-auth-library');
const client = new OAuth2Client();
async function verify() {
  const ticket = await client.verifyIdToken({
      idToken: token,
      audience: CLIENT_ID,  // Specify the CLIENT_ID of the app that accesses the backend
      // Or, if multiple clients access the backend:
      //[CLIENT_ID_1, CLIENT_ID_2, CLIENT_ID_3]
  });
  const payload = ticket.getPayload();
  const userid = payload['sub'];
  // If the request specified a Google Workspace domain:
  // const domain = payload['hd'];
}
verify().catch(console.error);

verifyIdToken 函数用于验证 JWT 签名、aud 声明、exp 声明 以及 iss 声明。

如果您需要验证 ID 令牌是否代表 Google Workspace 或 Cloud 组织账号时,您可以查看 hd 声明,该声明表示托管的 用户的网域。将资源访问权限限制为仅允许成员访问时,必须使用此设置 特定网域的用户缺少此声明即表示该账号不属于 Google 托管的域。

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PHP

要在 PHP 中验证 ID 令牌,请使用适用于 PHP 的 Google API 客户端库。 安装该库(例如,使用 Composer):

composer require google/apiclient
然后,调用 verifyIdToken() 函数。例如:

require_once 'vendor/autoload.php';

// Get $id_token via HTTPS POST.

$client = new Google_Client(['client_id' => $CLIENT_ID]);  // Specify the CLIENT_ID of the app that accesses the backend
$payload = $client->verifyIdToken($id_token);
if ($payload) {
  $userid = $payload['sub'];
  // If the request specified a Google Workspace domain
  //$domain = $payload['hd'];
} else {
  // Invalid ID token
}

verifyIdToken 函数用于验证 JWT 签名、aud 声明、exp 声明 以及 iss 声明。

如果您需要验证 ID 令牌是否代表 Google Workspace 或 Cloud 组织账号时,您可以查看 hd 声明,该声明表示托管的 用户的网域。将资源访问权限限制为仅允许成员访问时,必须使用此设置 特定网域的用户缺少此声明即表示该账号不属于 Google 托管的域。

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Python

要在 Python 中验证 ID 令牌,请使用 verify_oauth2_token 函数。例如:

from google.oauth2 import id_token
from google.auth.transport import requests

# (Receive token by HTTPS POST)
# ...

try:
    # Specify the CLIENT_ID of the app that accesses the backend:
    idinfo = id_token.verify_oauth2_token(token, requests.Request(), CLIENT_ID)

    # Or, if multiple clients access the backend server:
    # idinfo = id_token.verify_oauth2_token(token, requests.Request())
    # if idinfo['aud'] not in [CLIENT_ID_1, CLIENT_ID_2, CLIENT_ID_3]:
    #     raise ValueError('Could not verify audience.')

    # If the request specified a Google Workspace domain
    # if idinfo['hd'] != DOMAIN_NAME:
    #     raise ValueError('Wrong domain name.')

    # ID token is valid. Get the user's Google Account ID from the decoded token.
    userid = idinfo['sub']
except ValueError:
    # Invalid token
    pass

verify_oauth2_token 函数验证 JWT 签名、aud 声明和 exp 声明。 您还必须验证 hd 检查 verify_oauth2_token 返回。如果多个客户端访问 后端服务器,另请手动验证 aud 声明。

调用 tokeninfo 端点

调试验证 ID 令牌签名的一种简单方法是 使用 tokeninfo 端点。调用此端点涉及 这个额外的网络请求会为您完成大部分的验证工作, 验证和载荷提取。不适合在生产环境中使用 因为请求可能会受到限制或出现间歇性错误。

如需使用 tokeninfo 端点验证 ID 令牌,请创建 HTTPS POST 或 GET 请求发送到端点,并在 id_token 参数。 例如,要验证令牌“XYZ123”,请发出以下 GET 请求:

https://oauth2.googleapis.com/tokeninfo?id_token=XYZ123

如果令牌经过正确签名,并且 issexp 具有预期值,就会收到 HTTP 200 响应,其中正文 包含 JSON 格式的 ID 令牌声明。 以下是示例响应:

{
 // These six fields are included in all Google ID Tokens.
 "iss": "https://accounts.google.com",
 "sub": "110169484474386276334",
 "azp": "1008719970978-hb24n2dstb40o45d4feuo2ukqmcc6381.apps.googleusercontent.com",
 "aud": "1008719970978-hb24n2dstb40o45d4feuo2ukqmcc6381.apps.googleusercontent.com",
 "iat": "1433978353",
 "exp": "1433981953",

 // These seven fields are only included when the user has granted the "profile" and
 // "email" OAuth scopes to the application.
 "email": "testuser@gmail.com",
 "email_verified": "true",
 "name" : "Test User",
 "picture": "https://lh4.googleusercontent.com/-kYgzyAWpZzJ/ABCDEFGHI/AAAJKLMNOP/tIXL9Ir44LE/s99-c/photo.jpg",
 "given_name": "Test",
 "family_name": "User",
 "locale": "en"
}

如果您需要验证 ID 令牌是否代表 Google Workspace 账号,可以先查看 hd 声明,指示用户的托管网域。只有在以下情况下, 从而仅允许特定网域中的成员访问资源。缺少此声明 表示该账号不属于 Google Workspace 托管网域。

创建账号或会话

验证令牌后,检查用户是否已经在您的用户数据库中。如果是,请为用户建立经过身份验证的会话。如果用户不在您的用户数据库中,请根据 ID 令牌载荷中的信息创建新的用户记录,并为用户建立会话。当您在应用中检测到新创建的用户时,可以提示用户提供所需的任何其他个人资料信息。

使用跨账号保护功能保护用户账号

如果您依靠 Google 让用户登录,则会自动受益于 Google 为保护用户数据而构建的所有安全功能和基础架构。不过,万一用户的 Google 帐号遭到入侵或发生其他重大安全性事件,您的应用也很容易遭到攻击。为了更好地保护您的账号免受任何重大安全性事件的影响,请使用跨账号保护功能接收来自 Google 的安全提醒。收到这些事件后,您就可以深入了解用户 Google 帐号安全性方面的重要变化,然后根据自己的服务采取措施,以确保帐号安全。