{
  flake,
  config,
  ...
}:
let
  inherit (flake.config.people) user0 user1;
  inherit (flake.config.machines) devices;
  hostname = config.networking.hostName;
  mars = devices.mars.name;
  deimos = devices.deimos.name;
  ceres = devices.ceres.name;

  getUserKeys = user: flake.config.people.users.${user}.sshKeys;

  user0Key = {
    ${user0} = {
      openssh.authorizedKeys.keys = getUserKeys user0;
    };
  };
  user1Key = {
    ${user1} = {
      openssh.authorizedKeys.keys = getUserKeys user1;
    };
  };

in
{
  users.users =
    if hostname == mars then
      user0Key // user1Key
    else if
      builtins.elem hostname [
        deimos
        ceres
      ]
    then
      user0Key
    else
      { };
}