Maybe something’s change since the writing of the script in 2019?
I systematically got a “Unable to extract SecureTar - Maybe your password is wrong or the tar is not password encrypted?” message even on freshly created backups .
follow the instructions above, but in a cmd indow instead of the nano command use notepad (or your favorite text editor) and use that to create your decrypt.py file
install the cryptography module by doing: pip install cryptography
then run the same python command above, but your executable might be python or py instead of python3.
I was pulling my hair out trying to get files out of a password protected backup. It was a long journey of not getting why other tar unpackers would not unpack the tar even with the password. Many thanks for this script worked a charm in WSL