  We introduce SemanticLock, a single factor graphical authentication solution
for mobile devices. SemanticLock uses a set of graphical images as password
tokens that construct a semantically memorable story representing the user`s
password. A familiar and quick action of dragging or dropping the images into
their respective positions either in a \textit{continous flow} or in
\textit{discrete} movements on the the touchscreen is what is required to use
our solution.
  The authentication strength of the SemanticLock is based on the large number
of possible semantic constructs derived from the positioning of the image
tokens and the type of images selected. Semantic Lock has a high resistance to
smudge attacks and it equally exhibits a higher level of memorability due to
its graphical paradigm.
  In a three weeks user study with 21 participants comparing SemanticLock
against other authentication systems, we discovered that SemanticLock
outperformed the PIN and matched the PATTERN both on speed, memorability, user
acceptance and usability. Furthermore, qualitative test also show that
SemanticLock was rated more superior in like-ability. SemanticLock was also
evaluated while participants walked unencumbered and walked encumbered carrying
"everyday" items to analyze the effects of such activities on its usage.
