  Android's graphical password unlock remains one of the most widely used
schemes for phone unlock authentication, and it is has been studied extensively
in the last decade since its launch. We have learned that users' choice of
patterns mimics the poor password choices in other systems, such as PIN or
text-based passwords. A wide variety of analysis and data collections methods
was used to reach these conclusions, but what is missing from the literature is
a systemized comparison of the related work in this space that compares both
the methodology and the results. In this paper, we take a detailed accounting
of the different methods applied to data collection and analysis for Android
unlock patterns. We do so in two dimensions. First we systemize prior work into
a detailed taxonomy of collection methods, and in the second dimension, we
perform a detailed analysis of 9 different data sets collected using different
methods. While this study focuses singularly on the collection methods and
comparisons of the Android pattern unlock scheme, we believe that many of the
findings generalize to other graphical password schemes, unlock authentication
technology, and other knowledge-based authentication schemes.
