The coredecryptor python script is inaccessible from a web prowser because keybase.pub shut down almost a year ago. It was a separate service from Keybase itself IIRC.

However, according to this comment: https://news.ycombinator.com/item?id=34711449 it seems that you are still able to access the directory through the Keybase program itself. I am not sure how that would work though, because I haven't used Keybase since it was acquired by Zoom.