A simple observation attacks resistant PIN-entry scheme employing audios

One of the common drawbacks of existing observation attacks resistant PIN-entry schemes employing audios is that the user has to carry an earphone with him/her. Herein, we propose a simple observation attacks resistant PIN-entry scheme for mobile devices employing audios, Audio-PES, in which the device's receiver is used by the system to covertly transmit secret challenges to the user. In particular, earphones are not required in Audio-PES. We show that Audio-PES can achieve both sufficient security and high usability.