Passwordless SSH login fails

If you are attempting to log in to an openssh server using public key authorisation and it keeps asking for your password anyway then check the permissions on the ssh directory for the user account you are trying to log in as;

ls -al ~/.ssh
drwx------ 2 brett brett 4096 Jun  4 13:40 .
drwx------ 6 brett brett 4096 Jun  4 13:37 ..
-rwx------ 1 brett brett  398 Jun  4 13:40 authorized_keys


If the permissions are anything other than those shown above then you need to fix that;

chmod 700 ~/.ssh
chmod 700 ~/.ssh/*

apt-get BADSIG 40976EAF437D05B5

As root, enter these commands;

apt-get clean
cd /var/lib/apt
mv lists lists.old
mkdir -p lists/partial
apt-get clean
apt-get update

Thanks to Luigi