Android(Google登录)：如何验证服务器上ID令牌的完整性？

我使用此方法获取ID令牌：

GoogleSignInAccount acct = googleSignInResult.getSignInAccount();
String toekn_id = acct.getIdToken();

现在,如何验证服务器上ID令牌的完整性？

谷歌：

Warning: Do not accept plain user IDs, such as those you can get with the GoogleSignInAccount.getId() method, on your backend server. A modified client application can send arbitrary user IDs to your server to impersonate users, so you must instead use verifiable ID tokens to securely get the user IDs of signed-in users on the server side.

解决方法:

来自文档：https://developers.google.com/identity/sign-in/web/backend-auth#using-a-google-api-client-library

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)
    .setAudience(Arrays.asList(CLIENT_ID))
    // If you retrieved the token on Android using the Play Services 8.3 API or newer, set
    // the issuer to "https://accounts.google.com". Otherwise, set the issuer to
    // "accounts.google.com". If you need to verify tokens from multiple sources, build
    // a GoogleIdTokenVerifier for each issuer and try them both.
    .setIssuer("https://accounts.google.com")
    .build();

// (Receive idTokenString by HTTPS POST)

GoogleIdToken idToken = verifier.verify(idTokenString);
if (idToken != null) {
  System.out.println("Valid ID token.");

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

您可以在此处阅读api文档：http://javadoc.google-api-java-client.googlecode.com/hg/1.18.0-rc/com/google/api/client/googleapis/auth/oauth2/GoogleIdTokenVerifier.html

要使用这些API,请将以下内容添加到build.gradle中：

repositories {
    mavenCentral()
}
dependencies {
    compile 'com.google.api-client:google-api-client:1.20.0'
}