# Perform Transaction Authentication
source: https://developer.mastercard.com/mastercard-checkout-solutions/tutorial/authentication_c2p_guide/scenario1/index.md

## Transaction Authentication Performed by Mastercard {#transaction-authentication-performed-by-mastercard}

Integrator requests transaction authentication during the checkout method, and Mastercard uses the applicable method to perform authentication.

**User Experience**

![Passkey Authentication in Click to Pay](https://static.developer.mastercard.com/content/mastercard-checkout-solutions/documentation/images/ux_wireframes_recognized_user_newdevice03.png)

This use case is for illustration purpose only. ***To gain complete information about Transaction Authentication Service, go to the \[Product Guide\]*.**

On performing the checkout with Transaction Authentication, Integrator receives the checkout response, verifies the customer payment, and calls the checkout API to retrieve the transaction payload with cloud token and DSRPv3 cryptogram.

Refer to technical integration steps in [TAS for Click to Pay tutorial](https://developer.mastercard.com/mastercard-checkout-solutions/tutorial/authentication_c2p/step1/index.md).