Here’s something I was faced with and conquered:

I was compiling my AIR application and did not want a SWF file to be left in the directory. You could decompile it, you could try to open it on its own, and it just looked unprofessional. So in order to resolve this I thought, “Well I can just rename it to something else.” But that was not quite the effect I wanted.

What I ended up doing was dividing it up into multiple files, scrambling the data inside, encrypting each file, and spreading them out. This makes it so that no one can actually just throw your SWF into a decompiler and looks a little more legitimate.

The reason this can be done is because of ByteArray, File, Loader, and LoaderContext. What you do is:

• Create a ByteArray
• One-by-one write each file’s data to the ByteArray in the correct order
• Use: loaderContext.allowLoadBytesCodeExecution
• Create a Loader and load the Bytes in ByteArray:  loader.loadBytes( your_byte_array, loaderContext );

“allowLoadBytesCodeExecution” will actually let you load a file from its internals rather than creating an archive on the system first. If there is no archive, there is nothing to decompile.

With this method, you can split your file into multiple sections, encrypt the code in different ways, and more. Some possible uses:

• Encrypt files using a personal salt (password) so it is password protected
• Encrypt files using MAC address so it only works on a specified computer

I have it working well and all, but there is still more to experiment with. I just thought I would share the good news!

This entry was posted on Tuesday, November 18th, 2008 at 2:04 am and is filed under Actionscript 3.0. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.