Q:

How to open a Base64 encrypted 7z File on Windows? 

As the title already describes, I have a text file with base64-code which was originally a password protection *.7z file. 
How do I proceed correctly to get the content from this file, under Windows? 

My attempt so far was

Decode Content of Text File in ASCII (with a simple Python 2.7 Script)
Save Output as *.7z
Try to open this File with 7-Zip

But that did not work.  If i try to open the file 7-Zip tells me, "{Target File} is no Archive". 

An example File
http://pastebin.com/f1Rqgs7c

A:

You can use 
certutil -decode base64encoded.7z decoded.7z

and then open the 7z file in 7Zip, enter the password etc.  as usual.