Reference: https://github.com/LnL7/nix-docker
# If on Darwin, I recommend keeping nix stuff contained
mkdir -p /nix/etc/nix
ln -s /nix/etc/nix /etc/nix # sysconfdir; can be overridden with $NIX_CONF_DIR
cd /nix/etc/nix/
openssl genrsa -out signing-key.sec 2048
openssl rsa -in signing-key.sec -pubout > signing-key.pub