PhoenixTool (Andy's tool) source code?

Is there a way of getting the source code of Phoenix Tool (Andy's tool)?

More specifically I need the hewprsa.exe code.

What I need are two things:

• Understand how unencryption is performed for InsydeFlash BIOSes.
  
• Be able to update the keys in case they are changed in new BIOSes versions.
  

I can contribute the changes, or the new keys if happen to be updated.

If this is not possible, if someone can lend me a hand and tell me how the unencryption works so I can replicate the work, I would be very grateful. I have just found this forum and it is truly great. Planning to stay around. 

Thanks