I have the same problem as describe in the SSH to a login to Ubuntu Core on Raspberry Pi requires password.
I create a SSH key with Ubuntu MATE 16.04 installed on a VirtualBox VM
The key was created with the https://help.ubuntu.com/community/SSH/OpenSSH/Keys webpage instructions.
I transfert the public key on my SSO account.
When I boot my Raspberry Pi 3, I do the installation process and I have provided my account information.
To connect to the RPi3, I tried the following different methods.
- My SSO usersname with the RSA key pathphrase.
- My SSO email with the RSA key pathphrase.
- My SSO email with SSO password.
- My SSO username with SSO password.
- Ubuntu / ubuntu.
- My SSO username with no password.
None of these methods allowed me to login.