To change .ssh and its files user and group
chown -R your_user:your_user .ssh
Folder and file permission ss for rights, go with 700 for .ssh and 600 for authorized_keys and other files.
chmod 700 .ssh
chmod 600 .ssh/authorized_keys
Keys need to be only readable by you:
chmod 400 ~/.ssh/id_rsa
If Keys need to be read-writable by you:
chmod 600 ~/.ssh/id_rsa