function login(form, url_base) {
  var field = $("login-form-errors");
  field.innerHTML = "";
  field = $('email-field-label');
  Element.removeClassName(field, 'field-error');
  field = $('password-field-label');
  Element.removeClassName(field, 'field-error');
  
  form.elements['password'].value = hex_hmac_md5(form.elements['password'].value, form.elements['email'].value);
  new Ajax.Request(url_base + "/account/login.php", {
    asynchronous: true,
    method: "post",
    parameters: "email=" + form.elements['email'].value
      + "&password=" + form.elements['password'].value,
    onSuccess: function(request) {
	//alert(request.responseText);
      eval(request.responseText);
    },
    onFailure: function(request, object) {
      alert("Failure: "+object+"\n"+request.responseText);
    },
    onException: function(request, exception) {
      alert("Exception: "+exception+"\n"+request.responseText);
    }
  });
  form.elements['password'].value = "";
  
  return false;
}