CI_Encryption::_mcrypt_encrypt PHP Method

    protected function _mcrypt_encrypt($data, $params)
    {
        if (!is_resource($params['handle'])) {
            return FALSE;
        }
        // The greater-than-1 comparison is mostly a work-around for a bug,
        // where 1 is returned for ARCFour instead of 0.
        $iv = ($iv_size = mcrypt_enc_get_iv_size($params['handle'])) > 1 ? mcrypt_create_iv($iv_size, MCRYPT_DEV_URANDOM) : NULL;
        if (mcrypt_generic_init($params['handle'], $params['key'], $iv) < 0) {
            if ($params['handle'] !== $this->_handle) {
                mcrypt_module_close($params['handle']);
            }
            return FALSE;
        }
        // Use PKCS#7 padding in order to ensure compatibility with OpenSSL
        // and other implementations outside of PHP.
        if (in_array(strtolower(mcrypt_enc_get_modes_name($params['handle'])), array('cbc', 'ecb'), TRUE)) {
            $block_size = mcrypt_enc_get_block_size($params['handle']);
            $pad = $block_size - self::strlen($data) % $block_size;
            $data .= str_repeat(chr($pad), $pad);
        }
        // Work-around for yet another strange behavior in MCrypt.
        //
        // When encrypting in ECB mode, the IV is ignored. Yet
        // mcrypt_enc_get_iv_size() returns a value larger than 0
        // even if ECB is used AND mcrypt_generic_init() complains
        // if you don't pass an IV with length equal to the said
        // return value.
        //
        // This probably would've been fine (even though still wasteful),
        // but OpenSSL isn't that dumb and we need to make the process
        // portable, so ...
        $data = mcrypt_enc_get_modes_name($params['handle']) !== 'ECB' ? $iv . mcrypt_generic($params['handle'], $data) : mcrypt_generic($params['handle'], $data);
        mcrypt_generic_deinit($params['handle']);
        if ($params['handle'] !== $this->_handle) {
            mcrypt_module_close($params['handle']);
        }
        return $data;
    }