SSH:
keygen
(uses a randomizer)
ELLIPTIC CURVES
(ssh-keygen -t ecdsa -N "" -C "" -b 521 -f ECDSA_521_key)
ssh-keygen -t ed25519
ssh-keygen -t ecdsa -b 521
RSA
(ssh-keygen -t rsa -N "" -b 3072 -C "" -f RSA && mv RSA RSA.private && mv RSA.pub RSA.public)
ssh-keygen -t rsa -b 4096
AGENT
ssh-agent
ADD
ssh-add ECDSA_521_KEY
GITLAB USAGE
https://docs.gitlab.com/ee/user/ssh.html#configure-ssh-to-point-to-a-different-directory