Security Evaluation of Distortion Technique for Graphical Authentication

Abstract

Extensive research has been done on graphical-based authentication schemes that focus on memorability issues. However, less consideration has been given to the new security threat imposed towards these schemes. The downside of this graphical authentication is that the images may expose more information than text, and this makes it more vulnerable to security threats such as shoulder surfing attack. This study evaluates the significance of using distorted images as a variable of countermeasure to shoulder surfing attack on graphical password systems. Filter strength was applied to indicate distortion level which may influence the resiliency of the graphical based password. An experiment was conducted on 45 participants to investigate whether image distortion may help to prevent or reduce shoulder surfing attack. The outcome showed that filter strength indeed plays a significant role to certain extends towards the distortion technique applied to combat shoulder surfing attack. The contributions of this study are valuable for improving the graphical based authentication system especially in providing better security as well as maintaining high usability.