{config, lib, ...}:
let
  alice = import ./alice;
  bob = import ./bob;
  mallory = import ./mallory;
  isSystemUser = _name: userConfig: userConfig.isSystemUser == true;
in
{
  users.users = {
    inherit alice;
    inherit bob;
    root = {
      openssh.authorizedKeys.keys = lib.lists.flatten (attrValues (lib.mapAttrs
        (_name: userConfig: userConfig.openssh.authorizedKeys.keys)
        (lib.filterAttrs isSystemUser config.users.users)))
    };
  };
}