Hi ctky, What USB smart card reader do you have? Mine cost about $35.
NOTE: Readers such as: SCR-331 & SCR-3500A may need a firmware update (NO OTHER Readers need firmware updates). 'Some, not all' CAC readers may need to have a driver installed to make it work. The apk file is an archive that contains source data of Android application (compiled dex files, compiled arsc files, AndroidManifest.xml file, settings files, source files, graphic files).