Following recommendations of the german BSI, we have removed the ssh key type RSA from the list of approved algorithms on the Lichtenberg.

Instead of RSA, we recommend the key type “ed25519” (based on elliptic curve cryptography) for all your ssh keys. This type is more secure (by the current state of knowledge), and for a comparable level of security shorter than RSA keys.

You can create such a key with

ssh-keygen -t ed25519 …

This tool asks interactively for all further details.

Please always assign a pass phrase to the private part of the key pair, as else just obtaining the private key would allow an attacker to digitally pretend being you.