Counting clicks and beeps: Exploring numerosity based haptic and audio PIN entry

► Haptic and audio cues can secure PIN entry processes from observation attack. ► Two interfaces for haptic and audio PIN entry using temporal numerosity (counting) are presented. ► Performance substantially improves over prior systems using cue recognition approaches. ► Numerosity based non-visual PIN entry is secure against observation attack. ► Numerosity is a promising new non-visual interaction paradigm.