Exploring the Effect of Resolution on the Usability of Locimetric Authentication

TL;DR

This study investigates how image resolution affects hot-spot formation in locimetric authentication, finding that higher resolution reduces hot-spots but does not eliminate them, suggesting additional mitigation strategies are needed.

Contribution

It provides empirical evidence that higher resolution images decrease hot-spot issues in locimetric authentication but do not fully solve the problem, highlighting the need for supplementary techniques.

Findings

Hot-spots are present in both low- and high-resolution images.

Higher resolution images reduce hot-spot concentration.

Additional controls are necessary to fully mitigate hot-spots.

Abstract

Locimetric authentication is a form of graphical authentication in which users validate their identity by selecting predetermined points on a predetermined image. Its primary advantage over the ubiquitous text-based approach stems from users' superior ability to remember visual information over textual information, coupled with the authentication process being transformed to one requiring recognition (instead of recall). Ideally, these differentiations enable users to create more complex passwords, which theoretically are more secure. Yet locimetric authentication has one significant weakness: hot-spots. This term refers to areas of an image that users gravitate towards, and which consequently have a higher probability of being selected. Although many strategies have been proposed to counter the hot-spot problem, one area that has received little attention is that of resolution. The hypothesis here is that high-resolution images would afford the user a larger password space, and consequently any hot-spots would dissipate. We employ an experimental approach, where users generate a series of locimetric passwords on either low- or high-resolution images. Our research reveals the presence of hot-spots even in high-resolution images, albeit at a lower level than that exhibited with low-resolution images. We conclude by reinforcing that other techniques - such as existing or new software controls or training - need to be utilized to mitigate the emergence of hot-spots with the locimetric scheme.