In one example embodiment, a card payment system includes a card payment apparatus, having an audio jack, configured to: read account information stored on a payment card, encode a counter value of the card payment apparatus into a onetime password, transmit the account information and onetime password via a microphone contact of the audio jack, and receive an acoustic signal via at least one earphone contact of the audio jack; and a client device, having an audio jack socket to receive the audio jack, configured to: receive the account information and onetime password via the microphone contact, transmit, to the card payment apparatus, the acoustic signal via the at least one earphone contact, decode the onetime password into the counter value, and authenticate the card payment apparatus based on the counter value of the card payment apparatus and a counter value of the client device.