Разрешения 0664 для /home/kapua/keys/dev11 слишком открыты.
chmod 600 ~/.ssh/id_rsa
Arrogant Anaconda
chmod 600 ~/.ssh/id_rsa
$ sudo chmod 600 /path/to/my/key.pem
chmod 400 /Users/username/.ssh/id_rsa
chmod 400 {keyfile}.pem is what amazon instructed and it works.
# if you are using WSL then include sudo before the commands
sudo ssh ...