  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.
