> For the complete documentation index, see [llms.txt](https://docs.payments.thalescloud.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.payments.thalescloud.io/merchant-tokenization/es/taf-de-mastercard/implement-taf/authenticate-a-transaction.md).

# Autenticar una transacción

Usa el SDK de Thales para autenticar una transacción con Mastercard Token Authentication Framework (TAF).

Esta llamada genera un payload de Mastercard. Úsalo para recuperar un criptograma de transacción elegible para TAF.

## Flujo de autenticación

<figure><img src="/files/e82fc008f15a3962208fb3c3cd9ea7fc333889a2" alt=""><figcaption><p>Flujo de autenticación de Mastercard TAF en el proceso de pago.</p></figcaption></figure>

## Integración del SDK

{% tabs %}
{% tab title="Android" %}
Llamada `MastercardTAFHelper.authenticateTransaction`.

Iniciar autenticación del dispositivo en `onDeviceAuthentication`.

Puedes personalizar las cadenas de la interfaz biométrica.

Gestiona el resultado final en `onSuccess` o `onError`.

```java
public void mastercard_AuthenticateTransaction(@NonNull final String tokenID, @NonNull TransactionContext transactionContext, @NonNull MastercardTAFHelper masterCardTAFHelper, @NonNull FragmentActivity fragmentActivity) {
    masterCardTAFHelper.authenticateTransaction(tokenID, transactionContext, new TransactionListener() {
        @Override
        public void onDeviceAuthentication(DeviceAuthentication deviceAuthentication) {
            CharSequence title = "Título";
            CharSequence subTitle = "Subtítulo";
            CharSequence description = "Descripción";
            CharSequence negativeButtonText = "Botón negativo";
            deviceAuthentication.startAuthentication(fragmentActivity,
                    title,
                    subTitle,
                    description,
                    negativeButtonText);
        }

        @Override
        public void onError(TMGClientException exception) {
            // Verifica el error
            int errorCode = exception.getErrorCode();
            String errorMessage = exception.getMessage();
        }

        @Override
        public void onSuccess(String payload) {
            // Decodifica el payload de Mastercard y verifica la aserción de la transacción
        }
    });
}
```

`onSuccess` devuelve el payload de Mastercard.

`onError` devuelve un `TMGClientException` con un código de error y un mensaje.
{% endtab %}

{% tab title="iOS" %}
Llamada `authenticateTransaction` con un `TransactionContext`.

Iniciar autenticación del dispositivo en `deviceAuthenticationHandler`.

```swift
let tokenID = ""
let transContext = MastercardTAFHelper.TransactionContext(merchantName: "ABC", amount: "100", currencyCode: "USD")
// 1. Iniciar la autenticación de la transacción
mastercardTAFHelper.authenticateTransaction(forTokenID: tokenID, context: transContext,
    deviceAuthenticationHandler: { auth in
        // 2. Iniciar la autenticación del usuario
        let customMessage = "" // Pasa el mensaje personalizado. p. ej.: "Autenticar con Face ID"
        auth.startAuthentication(withMessage: customMessage)
    },
    completionHandler: { (mastercardPayload, error) in
        // 3. Éxito al generar el payload
        if error == nil {
        
        } else {
            // Gestionar error
        }
    }
)
```

{% endtab %}
{% endtabs %}


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