Welcome to Krypton! The first level is easy. The following string encodes the password using Base64:
S1JZUFRPTklTR1JFQVQ=
Use this password to log in to krypton.labs.overthewire.org with username krypton1 using SSH on port 2231. You can find the files for other levels in /krypton/
Host: krypton.labs.overthewire.org
Port: 2231
Open your terminal, then run this command:
echo S1JZUFRPTklTR1JFQVQ= | base64 --decode

Alternatively, you can use the CyberChef online tool.

Great job! Use this flag to advance to the next stage.