This challenge starts off by giving us the password in base64 on the overthewire web site, and we have to decode it in order to log into the ssh account. There’s numerous ways to do this, including manually if you were so inclined. I elected to use the base64 utility on my local machine.
$ echo "S1JZUFRPTklTR1JFQVQ=" | base64 --decode
XXXXXXXXXXXXX