Unprotect sourcedefender protected files

The purpose of this project is to unprotect sourcedefender protected files.

It is easy to test:
create a python file with "print('hello world')" in it. And run sourcedefender (SD) (pip install sourcedefender) on it: "sourcedefender encrypt hello.py".

The file will appear with base64 encoded text. In the docs of SD it says that it has 256AES encryption.
Fine. But where is the key? It should be there, because you can just run python -m sourcedefender hello.pye (notice the ~e there -- it probably mean "encrypted"?)

So my assumption here is that either a default key is used, or the key is injected into the source file (because you can share the sources and it works everywhere as long as SD is installed). So the key will not be saved locally.

The purpose is to figure out how to decode the base64 text into normal Python code. And it might be possible that the encrypted text does not contain the sources anymore, but only bytecode. But I'm not certain about that.