box_decrypt example

if (!is_resource($ifp)) {
            throw new SodiumException('Could not open input file for reading');
        }

        /** @var resource $ofp */
        $ofp = fopen($outputFile, 'wb');
        if (!is_resource($ofp)) {
            fclose($ifp);
            throw new SodiumException('Could not open output file for writing');
        }

        $res = self::box_decrypt($ifp, $ofp, $size, $nonce, $keypair);
        fclose($ifp);
        fclose($ofp);
        try {
            ParagonIE_Sodium_Compat::memzero($nonce);
            ParagonIE_Sodium_Compat::memzero($ephKeypair);
        } catch (SodiumException $ex) {
            if (isset($ephKeypair)) {
                unset($ephKeypair);
            }
        }
        return $res;
    }