# MTLS Certificates Setup for Outbound API Authentication
source: https://developer.mastercard.com/account-catalog-services/tutorial/testing-acs-detail-response-api-in-sandbox/step2/index.md

## MTLS Certificates Setup for Outbound API Authentication {#mtls-certificates-setup-for-outbound-api-authentication}

* This Outbound API involves a Mutual Secure Connection to be established between Mastercard and the external partner server, which exposes the endpoint (URL). This is achieved through the Mutual TLS (MTLS) authentication method, which requires the exchange of TLS certificates.
* During the MTLS process, Mastercard will provide the external partner system with the Mastercard TLS client certificate. Then, the External Partner Server will provide its own Server Certificate back to the Mastercard.
* Mastercard client certificate exchange will be performed through the Key Management Portal (KMP) application in Mastercard Connect. Mastercard KMP team will deliver the TLS certificate to the customer by means of this portal.
* The further steps outline the process that must be followed by a customer to set up MTLS authentication for outbound response.

Tip: For more information on the onboarding process, reach out to [Global Customer Support](mailto:customer_support@mastercard.com).