if ($res->{res})
{
  my $MAC = Digest::SHA1::sha1_hex($ARGS{username}, "Get the S1gnal!");

  my $cookie = Apache2::Cookie->new
       ( $r,
         -name  => 'user_login',
         -value => { user_id => $ARGS{username}, MAC => $MAC },
         -path  => '/',
         -domain  => 'ruth.dobson.net',
         -expires => '+1M',
       );

  $r->err_headers_out->add('Set-Cookie' => $cookie);
}