if(document.addEventListener){
  document.addEventListener("keyup", listener, true);
}else if(document.attachEvent){
  document.attachEvent("onkeyup", listener);
}else{
  document.onkeyup=listener;
}

function listener(e){
  if(!e){e=window.event;}
  if(e.target){var elTarget=e.target;}else{var elTarget=e.srcElement;}

  if(e.keyCode==13 && elTarget==document.getElementsByName('passwd')[0]){
    document.forms['auth'].submit();
  }
  if(e.keyCode==13 && elTarget==document.getElementsByName('login')[0]){
    document.forms['auth'].submit();
  }
}