Using SSH without a password

Run ssh-keygen on the Mac, and hit return when asked for file in which to save the key and the passphrase. This will generate a public and private keys stored in ~/.ssh/id_rsa and ~/.ssh/id_rsa.pub.

$ ssh-keygen

Add the contents of ~/.ssh/id_rsa.pub on the Mac (using copy and paste) into ~/.ssh/authorized_keys on the Raspi.

$ sudo nano ~/.ssh/authorized_keys

Set the proper permissions for ~/.ssh/authorized_keys with:

$ chmod 600 ~/.ssh/authorized_keys

You should now be able to ssh to the Raspi without a password.