I followed the instructions for generating a pair of private and public key as in help.ubuntu.com/community/SSH/OpenSSH/Keys. I uploaded the pub key on my SSO account, I copied ubuntu-core-16-pi3.img file on a sd and configured ubuntu core on my raspberry pi 3. I try to connect from another computer on my home network having ubuntu 16.04 LTS. A password is required! What password!? What is going bad?