Pam ssh agent auth
The PAM module sys-auth/pam_ssh_agent_auth allows one to use a locally installed SSH key to authenticate for app-admin/sudo. This is useful for those who aren’t happy with completely passwordless sudo, but don’t want to be typing passwords all the time.
emerge --ask pam_ssh_agent_auth
Create SSH Keys
Have every user that would like this capability to follow the guide on the SSH wiki page and create the needed keys
Configure sudo to try using public keys, then fall back to normal password authentication
... auth [success=3 default=ignore] pam_ssh_agent_auth.so file=/etc/ssh/sudo_authorized_keys auth include system-auth account include system-auth session include system-auth ...
Configure sudoers to preserve the environment variable SSH_AUTH_SOCK
... Defaults env_keep += "SSH_AUTH_SOCK" ...
Add Desired User's Public Key
Repeat this process for every user desired for sudo authentication
cat /home/<user>/.ssh/*.pub >> /etc/ssh/sudo_authorized_keys
Extra: Launch ssh-agent upon login
echo "ssh-add" >> ~/.bash_profile