US Patent 10924924 Out-of-band key sharing using near-field communication

A vehicle includes a keypad mounted to an exterior of the vehicle, the keypad having a plurality of buttons, each button representing both a first value and a second value. The vehicle further includes a body controller, programmed to receive an input sequence entered via the keypad, validate whether the input sequence matches a predefined keycode, assuming the input sequence correctly entered the first value or the second value according to indications of which values of the keycode are the first value and which are the second value, and confirm pairing a mobile device to the vehicle responsive to the input sequence matching the keycode.