SSH Keys for PI

https://www.raspberrypi.org/documentation/remote-access/ssh/passwordless.md

http://www.aupcgroup.com/blog/index.php?/archives/4-Securing-Raspbian.html

Run these on the machine accessing your pi:

Replace 'user' with your login and host with the hostname.

ssh-keygen -t ed25519 -C user@host -f ~/.ssh/raspberrypi

cat ~/.ssh/raspberrypi.pub | ssh user@host 'cat >> .ssh/authorized_keys'