TYPO3 eID RSA login with ExtJS JSON

<?php
if (!defined('PATH_typo3conf'))
  die('Could not access this script directly!');

class MyLoginClass {
  public function main() {
    $extKey      = 'myextkey';
    $this->debug = t3lib_extMgm::isLoaded('devlog');
    // force debug off
    $this->debug = FALSE;

    $feUserObject              = tslib_eidtools::initFeUser();
    $feUserObject->writeDevLog = TRUE;

    $logintype = t3lib_div::_GP('logintype');
    $backend   = tx_rsaauth_backendfactory::getBackend();

    if ($logintype == 'login') {
      if ($this->debug) {
        t3lib_div::devLog('SESSION after login: ' . json_encode($_SESSION), $extKey, 0);
      }
      if ($feUserObject->user) {
        $feUserObject->fetchGroupData();

        $uid         = $feUserObject->user['uid'];
        $groupsCount = count($feUserObject->groupData['uid']);
        $groups      = $feUserObject->groupData['title'];
        return json_encode(array(
          'success' => TRUE,
          'username' => $feUserObject->user['username']
        ));
      } else {
        return json_encode(array(
          'success' => FALSE,
          'errors' => array(
            'reason' => 'Login error.'
          )
        ));
      }
    } elseif ($logintype == 'logout') {
      $feUserObject->logoff();
    } else {
      if ($feUserObject->user) {
        return json_encode(array(
          'success' => true,
          'data' => array(
            array(
              'xtype' => 'displayfield',
              'value' => $feUserObject->user['username'],
              'fieldLabel' => 'Username'
            ),
            array(
              'xtype' => 'displayfield',
              'value' => $feUserObject->user['email'],
              'fieldLabel' => 'E-mail'
            ),
            array(
              'xtype' => 'displayfield',
              'value' => date('j.n.Y G:i:s T', $feUserObject->user['lastlogin']),
              'fieldLabel' => 'Last login'
            ),
            array(
              'xtype' => 'hidden',
              'name' => 'logintype',
              'value' => 'logout'
            )
          )
        ));
      } else {
        if (trim($GLOBALS['TYPO3_CONF_VARS']['FE']['loginSecurityLevel']) === 'rsa') {
          if ($backend->isAvailable()) {
            // Generate a new key pair
            $keyPair = $backend->createNewKeyPair();
            // Save private key
            $storage = tx_rsaauth_storagefactory::getStorage();
            /* @var $storage tx_rsaauth_abstract_storage */
            $storage->put($keyPair->getPrivateKey());
            if ($this->debug) {
              t3lib_div::devLog('SESSION before login: ' . json_encode($_SESSION), $extKey, 0);
            }
            $rsa_n = htmlspecialchars($keyPair->getPublicKeyModulus());
            $rsa_e = sprintf('%x', $keyPair->getExponent());
            return json_encode(array(
              'success' => true,
              'data' => array(
                array(
                  'xtype' => 'textfield',
                  'name' => 'user',
                  'fieldLabel' => 'Username',
                  'allowBlank' => FALSE,
                  blankText => 'Username is empty.'
                ),
                array(
                  'xtype' => 'textfield',
                  'name' => 'pass',
                  'fieldLabel' => 'Password',
                  'allowBlank' => FALSE,
                  'inputType' => 'password',
                  blankText => 'Password is empty.'
                ),
                array(
                  'xtype' => 'hidden',
                  'name' => 'logintype',
                  'value' => 'login'
                ),
                array(
                  'xtype' => 'hidden',
                  'name' => 'n',
                  'value' => $rsa_n
                ),
                array(
                  'xtype' => 'hidden',
                  'name' => 'e',
                  'value' => $rsa_e
                )
              )
            ));
          }
        }
      }
    }
  }
}

$output = t3lib_div::makeInstance('MyLoginClass');
echo $output->main();
?>