C:\photos>convert -version
Version: ImageMagick 6.7.3-1 2011-10-12 Q16 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2011 ImageMagick Studio LLC
Features: OpenMP

C:\photos>convert orig.png key1.jpg secret.png

C:photos>convert orig.png -encipher key1.jpg secret.png

C:photos>convert secret.png -decipher key2.jpg deciphered.png