public function addCertificatePair($private_key_file, $public_key_file, $type = Zend_InfoCard_Cipher::ENC_RSA_OAEP_MGF1P, $password = null)
    {
        return $this->_infoCard->addCertificatePair($private_key_file, $public_key_file, $type, $password);
    }