I created a short video on how to configure Cisco ASA to allow a CLI user to authenticate with RSA keypair when connecting with SSH instead of username/password. See video below.
In short, this is how to do it:
username johndoe nopassword
username johndoe attributes
ssh authentication publickey XXXXXXXX
(Replace XXXXXX with the users public key)
When connecting with “ssh johndoe@firewallip” the user will be granted CLI access without a password prompt.