Flash Protection Gold is one of the best program to protect SWF Flash files with an effective encryption technique for adobe flash ad flex. It provides three layers of extensive encryption techniques to stop flash/SWF decompilers and stop the illegal copying and redistribution of Flash (SWF), graphics including BITMAPS, Movieclips, Sounds, Videos, Text, Font and Action Script.
It lets you preview the flash file in the small Flash Player embedded in the program interface, you can select the encryption level. Moreover you can specify the domain lock which can prevent the application run out of the domain name specified.