> For the complete documentation index, see [llms.txt](https://docs.caf.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.caf.io/caf-sdk/caf-sdk-pt-br/flutter/standalone-modules/faceauthenticator/start-sdk.md).

# Iniciar verificação de vivacidade

## Chamando `startFaceAuthenticator`

Para iniciar a autenticação, inicialize `FaceAuth` com `mobileToken` e `personId`, depois chame `start()` e trate os eventos usando um listener:

```dart
  void startSDK() {
    final stream = _faceAuth.start();
    _setupFaceAuthListener(stream);
  }

  void _setupFaceAuthListener(Stream<FaceAuthEvent> stream) {
    stream.listen((event) {
      if (event is FaceAuthEventConnecting) {
        print('Conectando ao FaceAuth...');
      } else if (event is FaceAuthEventConnected) {
        print('Conectado ao FaceAuth.');
      } else if (event is FaceAuthEventClosed) {
        print('SDK fechado pelo usuário.');
      } else if (event is FaceAuthEventSuccess) {
        print('Sucesso! SignedResponse: ${event.signedResponse}');
      } else if (event is FaceAuthEventFailure) {
        print(
          'Falha! Tipo de erro: ${event.errorType}, '
              'Descrição do erro: ${event.errorDescription}',
        );
      }
    });
  }
```


---

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