I followed this to try to add authorized keys to my droplet. I ended up loosing permissions in my starting machine and not being able to log in from the second machine either.
I could not type '~' in the web console, so i am not able to authorize more keys either.
What can i do to overcome the: "Permission denied (public key)." error?
When logged in as root, /root/.ssh is equal to ~/.ssh, so if for one reason or another, you're unable to use ~, then /root/.ssh will work as a direct path.
In regards to /root/.ssh/authorized_keys, these are the public keys for the root user that are allowed to login. So if you're attempting to login to SSH using a command such as:
ssh root@DROPLET_IP -i /path/to/private_key
... then private_key needs to be associated with one of the public keys in authorized_keys on your Droplet, else authentication will fail.
What are the authorized keys? The ones present in the ~/.ssh/authorized_keys file or the ones in the profile settings of my digital ocean account?
By logging in again i was able to chmod 600 my ~/.ssh/authorized_keys and paste there my public key. It still does not work.
PS: Can't edit my question. How nice.
Not sure if this is your problem, but it was mine! I didn't realise that just because the root user had authorized_keys, doens't mean all the other users created do. I.e. if you create a VPS and Digital Ocean automatically adds SSH keys, these only go to the root user, so you have to mkdir .ssh for your new user and copy the SSH keys there and make sure the permissions correct.