Towards improving the usability of system-assigned PINs: can implicit learning techniques help?

Abstract

Personal Identification Numbers (PINs) are widely used for automated teller machines (ATMs), computers, mobile devices, debit cards, and credit cards. People tend to choose easy-to-recall PINs that are related to important dates (e.g., birthdays or anniversaries), or keypad patterns. Unfortunately, such easy-to-recall PINs can be vulnerable to guessing attacks. System-assigned PINs can improve PIN security; however, they are difficult to remember. This thesis designs and evaluates a set of training techniques to improve the usability of system-assigned PINs. We evaluate our designs through two studies (N=126 and N=184), showing that some designs improve usability in terms of login time and user perception. Our results suggest that some designs may also have the potential to improve PIN memorability. Our results should be of interest to practitioners and researchers working on authentication systems and usability.