Hey, I'm having issues with fetchgitPrivate when trying to build a project.

I'm currently invoking `nix-shell -I ssh-config-file=/home/sam/.nixpkgs/ssh/nixbuild.config`
and getting:
`Can't open user config file /home/sam/.nixpkgs/ssh/nixbuild.config: Permission denied`.
I'm assuming this has something to do with the nixbld users not being able to
access the config file. How do I properly set up my ssh keys for NixOS?