Jonathan M. McCune Adrian Perrig Michael K. Reiter Seeing-Is-Believing: Using Camera Phones for Human-Verifiable Authentication. 110-124 2005 conf/sp/2005 IEEE Symposium on Security and Privacy http://doi.ieeecomputersociety.org/10.1109/SP.2005.19 db/conf/sp/sp2005.html#McCunePR05