Introduction

This document outlines and explains the key functionalities, concepts, and dependencies of the ACS application.

The ACS (Access Control Server) is a component of the 3-D Secure protocol that operates within the issuer domain. Its primary role is to authenticate the cardholder during an e-commerce transaction. The ACS is responsible for verifying the cardholder's identity and deciding whether to approve authentication based on the data received in the authentication request.

As part of the 3-D Secure protocol, the ACS works in coordination with other components—ACS, 3DS Server, and Directory Server—to facilitate cardholder authentication. The protocol is designed to add an extra layer of security to online transactions and reduce the risk of fraud.