A method of remotely configuring a pin-pad terminal involves a computer server receiving a merchant identifier over a network from a communications device associated with the pin-pad terminal. The computer server confirms from the merchant identifier that an entity associated with the communications device is authorized to use the pin-pad terminal, and authenticates the pin-pad terminal from a cryptographically-signed datum received from the communications device. The computer server then transmits to the pin-pad terminal via the communications device a configuration payload for installation in the pin-pad terminal. The configuration payload includes at least a payment symmetric cryptographic key set uniquely associated with the pin-pad terminal. The payment symmetric key set configures the pin-pad terminal to effect secure electronic payment via the communications device.