Abstract: A payment authentication service authenticates the identity of a payer during online transactions. The authentication service of the present invention allows a card issuer to verify a cardholder's identity using a variety of authentication methods, such as the use of passwords. Also, the only system participant requiring a certificate is the issuing financial institution. One embodiment of the invention for authenticating the identity of a cardholder during an online transaction involves querying an access control server to determine if a cardholder is enrolled in the payment authentication service, requests a password from the cardholder, verifies the password, and notifies a merchant whether the cardholder's authenticity has been verified. In another aspect of the invention, a chip card and the authentication service independently generate cryptograms that must match in order for the service to verify that the correct chip card is being used by the cardholder.