An Access Control Server (ACS) is a key component in the 3-D Secure (3DS) protocol used to authenticate cardholders during online transactions. Card issuers use 3DS ACS programs to verify the identity of the cardholder before authorizing a payment.
How does an ACS work in a 3-D Secure authentication flow
When a customer initiates an online payment, the ACS evaluates the transaction and determines whether additional authentication is needed. This could involve multi-factor authentication, biometric verification, or silent authentication that allows the transaction to proceed without any active authentication steps needed from the customer.
Modern ACS platforms support 3DS 2.0, which enables frictionless authentication and improved user experience by leveraging contextual data, such as device information, transaction history, and geolocation.
How does an ACS impact fraud for financial institutions?
A 3DS ACS can help reduce card-not-present (CNP) fraud by ensuring that only legitimate customers can complete online transactions. It also supports regulatory requirements like PSD2’s Strong Customer Authentication (SCA) and enhances customer confidence in digital payments.
Example
A customer attempts to make an online purchase. The ACS evaluates the transaction and, based on the risk level, either approves it silently or prompts the customer to authenticate using a fingerprint scan.
Additional resources:
Learn more: Entersekt's 3DS ACS can futureproof issuers’ 3DS
Blog: 3D Secure: 5 Steps to global compliance coverage.
Blog: 3D Secure: A data-open approach for a brighter banking future.