I have an old multibit.key file that I'm trying to import into Electrum.  The text file has +'s and ='s, which I understand means it was encrypted by Multibit, thus I cannot just import it into Electrum without unencrypting it first.  How can I do that?  I understand that if I download Multibit Classic, I can use that, but I can't find it anywhere reliable.  Can it be downloaded here?  https://github.com/Multibit-Legacy/multibit  If so, how do I download it for Windows? 

Alternatively, is there a way to unencrypt it without using Multibit Classic? 

Thanks.