Edinburgh Napier University

  Users gain access to cash, confidential information and services at Automated Teller Machines (ATMs) via an authentication process involving a Personal Identification Number (PIN). These users frequently have many different PINs, and fail to remember them without recourse to insecure behaviours. This is not a failing of users. It is a usability failing in the ATM authentication mechanism. This paper describes research executed to evaluate whether users find multiple graphical passwords more memorable than multiple PINs. The research also investigates the success of two memory augmentation strategies in increasing memorability of graphical passwords. The results demonstrate that multiple graphical passwords are substantially more effective than multiple PIN numbers. Memorability is further improved by the use of mnemonics to aid their recall.This study will be of interest to HCI practitioners and information security researchers exploring approaches to usable security.