Firebase Authentication을 사용하면 임시 익명 계정을 생성 및 사용하여 Firebase에 인증할 수 있습니다. 이 임시 익명 계정을 통해 아직 앱에 가입하지 않은 사용자들도 보안 규칙으로 보호받는 데이터를 사용할 수 있습니다. 익명 사용자가 앱에 가입하기로 결정하면 이 사용자의 로그인 인증 정보를 해당 익명 계정에 연결하여 사용자가 추후 세션에서도 보호받는 데이터를 계속 사용하도록 할 수 있습니다.
선택사항: 프로젝트를 Firebase Authentication with Identity Platform으로 업그레이드한 경우 자동 정리를 사용 설정할 수 있습니다. 이 설정을 사용하면 30일이 지난 익명 계정은 자동으로 삭제됩니다. 자동 정리가 사용 설정된 프로젝트에서는 익명 인증이 더 이상 사용량 한도 또는 결제 할당량에 포함되지 않습니다. 자동 정리를 참조하세요.
Firebase에 익명으로 인증
로그아웃 상태의 사용자가 Firebase의 인증이 필요한 앱 기능을 사용할 때 다음 절차를 밟으면 사용자를 익명으로 로그인시킬 수 있습니다.
프로그램에 정기적으로 실행되는 업데이트 루프(예: 초당 30회 또는 60회)가 있는 경우 다음과 같이 Auth::SignInAnonymouslyLastResult를 사용해 업데이트 시마다 한 번씩 결과를 확인할 수 있습니다.
firebase::Future<firebase::auth::AuthResult>result=auth->SignInAnonymouslyLastResult();if(result.status()==firebase::kFutureStatusComplete){if(result.error()==firebase::auth::kAuthErrorNone){firebase::auth::AuthResultauth_result=*result.result();printf("Sign in succeeded for `%s`\n",auth_result.user.display_name().c_str());}else{printf("Sign in failed with error '%s'\n",result.error_message());}}
다음과 같이 로그인한 사용자의 LinkWithCredential 메서드에 auth::Credential 객체를 전달합니다.
// Link the new credential to the currently active user.firebase::auth::Usercurrent_user=auth->current_user();firebase::Future<firebase::auth::AuthResult>result=current_user.LinkWithCredential(credential);
LinkWithCredential 호출이 성공하면 사용자의 신규 계정에서 익명 계정의 Firebase 데이터에 액세스할 수 있습니다.
자동 정리
프로젝트를 Firebase Authentication with Identity Platform으로 업그레이드한 경우 Firebase Console에서 자동 정리를 사용 설정할 수 있습니다. 이 기능을 사용 설정하면 Firebase에서 30일이 지난 익명 계정을 자동으로 삭제할 수 있습니다. 자동 정리가 사용 설정된 프로젝트에서는 익명 인증이 사용량 한도 또는 결제 할당량에 포함되지 않습니다.
자동 정리를 사용 설정한 후 만든 익명 계정은 생성 후 30일이 지나면 언제든지 자동으로 삭제될 수 있습니다.
기존 익명 계정은 자동 정리를 사용 설정한 후 30일이 지나면 자동으로 삭제될 수 있습니다.
자동 정리를 사용 중지해도 삭제 예약된 익명 계정은 삭제가 예약된 상태로 유지됩니다.
익명 계정을 로그인 방법에 연결하여 '업그레이드'할 경우 계정이 자동으로 삭제되지 않습니다.
[null,null,["최종 업데이트: 2025-08-29(UTC)"],[],[],null,["You can use Firebase Authentication to create and use temporary anonymous accounts\nto authenticate with Firebase. These temporary anonymous accounts can be used to\nallow users who haven't yet signed up to your app to work with data protected\nby security rules. If an anonymous user decides to sign up to your app, you can\n[link their sign-in credentials to the anonymous\naccount](/docs/auth/cpp/account-linking) so that they can continue to work with their protected data in\nfuture sessions.\n\nBefore you begin\n\n1. [Add Firebase to your C++\n project](/docs/cpp/setup#note_select_platform).\n2. If you haven't yet connected your app to your Firebase project, do so from the [Firebase console](//console.firebase.google.com/).\n3. Enable anonymous auth:\n 1. In the [Firebase console](//console.firebase.google.com/), open the **Auth** section.\n 2. On the **Sign-in Methods** page, enable the **Anonymous** sign-in method.\n 3. **Optional** : If you've upgraded your project to [Firebase Authentication with Identity Platform](/auth#identity-platform), you can enable automatic clean-up. When you enable this setting, anonymous accounts older than 30 days will be automatically deleted. In projects with automatic clean-up enabled, anonymous authentication will no longer count toward usage limits or billing quotas. See [Automatic clean-up](#auto-cleanup).\n\nAuthenticate with Firebase anonymously\n\nWhen a signed-out user uses an app feature that requires authentication with\nFirebase, sign in the user anonymously by completing the following steps:\nThe `Auth` class is the gateway for all API calls.\n\n1. Add the Auth and App header files: \n\n ```c++\n #include \"firebase/app.h\"\n #include \"firebase/auth.h\"\n ```\n2. In your initialization code, create a [`firebase::App`](/docs/reference/cpp/class/firebase/app) class. \n\n ```c++\n #if defined(__ANDROID__)\n firebase::App* app =\n firebase::App::Create(firebase::AppOptions(), my_jni_env, my_activity);\n #else\n firebase::App* app = firebase::App::Create(firebase::AppOptions());\n #endif // defined(__ANDROID__)\n ```\n3. Acquire the `firebase::auth::Auth` class for your `firebase::App`. There is a one-to-one mapping between `App` and `Auth`. \n\n ```c++\n firebase::auth::Auth* auth = firebase::auth::Auth::GetAuth(app);\n ```\n\n- Call `Auth::SignInAnonymously`. \n\n ```c++\n firebase::Future\u003cfirebase::auth::AuthResult\u003e result =\n auth-\u003eSignInAnonymously();\n ```\n- If your program has an update loop that runs regularly (say at 30 or 60 times per second), you can check the results once per update with `Auth::SignInAnonymouslyLastResult`: \n\n ```c++\n firebase::Future\u003cfirebase::auth::AuthResult\u003e result =\n auth-\u003eSignInAnonymouslyLastResult();\n if (result.status() == firebase::kFutureStatusComplete) {\n if (result.error() == firebase::auth::kAuthErrorNone) {\n firebase::auth::AuthResult auth_result = *result.result();\n printf(\"Sign in succeeded for `%s`\\n\",\n auth_result.user.display_name().c_str());\n } else {\n printf(\"Sign in failed with error '%s'\\n\", result.error_message());\n }\n }\n ```\n Or, if your program is event driven, you may prefer to [register a callback on the\n Future](#register_callback_on_future).\n| To protect your project from abuse, Firebase limits the number of new email/password and anonymous sign-ups that your application can have from the same IP address in a short period of time. You can request and schedule temporary changes to this quota from the [Firebase console](//console.firebase.google.com/project/_/authentication/providers).\n\nConvert an anonymous account to a permanent account\n- When an anonymous user signs up to your app, you might want to allow them to continue their work with their new account---for example, you might want to make the items the user added to their shopping cart before they signed up available in their new account's shopping cart. To do so, complete the following steps:\n 1. When the user signs up, complete the sign-in flow for the user's authentication provider up to, but not including, calling one of the `Auth::SignInWith` methods. For example, get the user's Google ID token, Facebook access token, or email address and password.\n 2. Get an `auth::Credential` for the new authentication provider:\n\n **Google Sign-In** \n\n ```c++\n firebase::auth::Credential credential =\n firebase::auth::GoogleAuthProvider::GetCredential(google_id_token,\n nullptr);\n ```\n **Facebook Login** \n\n ```c++\n firebase::auth::Credential credential =\n firebase::auth::FacebookAuthProvider::GetCredential(access_token);\n ```\n **Email-password sign-in** \n\n ```c++\n firebase::auth::Credential credential =\n firebase::auth::EmailAuthProvider::GetCredential(email, password);\n ```\n 3. Pass the `auth::Credential` object to the sign-in user's\n `LinkWithCredential` method:\n\n ```c++\n // Link the new credential to the currently active user.\n firebase::auth::User current_user = auth-\u003ecurrent_user();\n firebase::Future\u003cfirebase::auth::AuthResult\u003e result =\n current_user.LinkWithCredential(credential);\n ```\n- If the call to `LinkWithCredential` succeeds, the user's new account can access the anonymous account's Firebase data.\n| This technique can also be used to [link any two accounts](/docs/auth/cpp/account-linking).\n\nAutomatic clean-up\n- If you've upgraded your project to [Firebase Authentication with Identity Platform](/docs/auth#identity-platform), you can enable automatic clean-up in the Firebase console. When you enable this feature you allow Firebase to automatically delete anonymous accounts older than 30 days. In projects with automatic clean-up enabled, anonymous authentication will not count toward usage limits or billing quotas.\n - Any anonymous accounts created after enabling automatic clean-up might be automatically deleted any time after 30 days post-creation.\n - Existing anonymous accounts will be eligible for automatic deletion 30 days after enabling automatic clean-up.\n - If you turn automatic clean-up off, any anonymous accounts scheduled to be deleted will remain scheduled to be deleted.\n - If you \"upgrade\" an anonymous account by linking it to any sign-in method, the account will not get automatically deleted.\n- If you want to see how many users will be affected before you enable this feature, and you've upgraded your project to [Firebase Authentication with Identity Platform](/docs/auth#identity-platform), you can filter by `is_anon` in [Cloud\n Logging](https://cloud.google.com/logging/docs).\n\nNext steps\n- Now that users can authenticate with Firebase, you can control their access to data in your Firebase database using [Firebase rules](/docs/database/security#section-authorization)."]]
