Patent ID: 7983993

Claim:
A computer-implemented method, performed by a computer system comprising one or more processors and computer memory, for authenticating an electronic payment transaction over a communications network, comprising: at a payment authentication service operated by the computer system, linking secret information to at least a first payment instrument of a buyer in computer memory, the secret information being known only to the buyer; receiving an electronic request to authenticate the buyer as being authorized to use the first payment instrument in an electronic payment transaction; subsequent to the step of linking the secret information to the first payment instrument in computer memory and in response to receiving the electronic request to authenticate the buyer, sending a challenge request to the buyer over the network, the challenge request including a summary of the payment transaction; subsequent to the step of linking the secret information to the first payment instrument in computer memory, receiving an electronic indication of a selection of the first payment instrument from the buyer; receiving a challenge response from the buyer over the network, the challenge response proving that the buyer has access to the secret information; in response to receiving the challenge response, determining that the buyer has access to the secret information and that the buyer is authorized to use the first payment instrument; and notifying a seller that the buyer is authorized to use the first payment instrument.