protected function _getUserCredentials(CakeRequest $request) {
		$externalAuth = $this->_useExternalAuth();
		$usr = null;
		$pwd = null;

		if ($externalAuth) {
			$user = env('REMOTE_USER');
			if (empty($user)) {
				$user = env('REDIRECT_REMOTE_USER');
			}
			if (empty($user) || !is_string($user)) {
				return compact('usr', 'pwd');
			}

			$usr = $user;
		} else {
			$userModel = $this->settings['userModel'];
			$objectModel = ClassRegistry::init($userModel, true);
			if ($objectModel === false) {
				return compact('usr', 'pwd');
			}

			$fields = $this->settings['fields'];
			if (!$this->_checkFields($request, $objectModel->alias, $fields)) {
				return compact('usr', 'pwd');
			}

			$user = $request->data[$objectModel->alias][$fields['username']];
			if (empty($user) || !is_string($user)) {
				return compact('usr', 'pwd');
			}

			$pswd = $request->data[$objectModel->alias][$fields['password']];
			if (empty($pswd) || !is_string($pswd)) {
				return compact('usr', 'pwd');
			}

			$usr = $user;
			$pwd = $pswd;
		}

		return compact('usr', 'pwd');
	}