I added optional key encryption and LZMA compression. Enjoy.
Edit: At the time of writing this, I forgot to include the new download archive.
https://dimensionscape.com/downloads/SWFOBBv1.0.4.0.zip
In the next version I will add optional support to convert ZIP or TAR files instead of SWF. I will also update the SWC with functions to easily and intuitively unpack assets from ZIP, TAR, and SWF and provide allowCode parameters. In a later build I will also address this:
"Caution: It is critical that you include the necessary code to download the expansion files from Google Play in the event that the files are not already on the device when your app starts."