Author: JessP

Here some simple steps for creating an additional user and copying their public ssh key:

Download private key, secure file:
chmod 600 myPrivateKey.pem

Publish .pem private key to OSX keychain:
ssh-add -K myPrivateKey.pem

Copy publickey to server
scp myPublicKey.pub user@ip:~

Create user, move key to
sudo adduser [new user] sudo
sudo mv myPublicKey.pub /home/[new user]/

Switch to su [new user]
mkdir ~/.ssh
chmod 700 ~/.ssh
sudo cat myPublicKey.pub >> ~/.ssh/authorized_keys

If errors you may need to take ownership:
sudo chown -R [new user]:[new user] /home/[new user]/.ssh/authorized_keys

Check key and logon:
cat authorized_keys
ssh [~.amazonaws.com]

Secure files:
chmod 600 ~/.ssh/authorized_keys

Copy files and directorys to AWS server:
scp -r * [ip]:~/temp/

Also use this to add pub direct:
cat myPublicKey.pub | ssh user@[ip] “cat >> ~/.ssh/authorized_keys”

Reference:
https://help.ubuntu.com/community/SSH/OpenSSH/Keys
https://www.digitalocean.com/community/tutorials/how-to-set-up-ssh-keys–2
http://blogs.aws.amazon.com/security/post/Tx3N8GFK85UN1G6/Securely-connect-to-Linux-instances-running-in-a-private-Amazon-VPC