If compiled executable is unencrypted, it can be compressed for distribution, then it must be decompressed to run on target PC and the code can be decompiled easily. If compiled executable is encrypted, the compression is ineffective which brings problem of distribution. With Level III of ReFox XII the encryption and compression are combined into one step. No additional library files or support DLL’s are required to run the application, only the standard RT module is used and it is modified on the fly when loaded into memory. EXEs are compressed to 25% of original size and decompressed into memory only when run. The application is protected by modified encryption method to disable ReFox and other decompilers from decompiling the code.