ParagonIE_Sodium_File::secretbox_encrypt_core32( resource $ifp, resource $ofp, int $mlen, string $nonce, string $key ): bool

1376    protected static function secretbox_encrypt_core32($ifp, $ofp, $mlen, $nonce, $key)1377    {1378        $plaintext = fread($ifp, 32);1379        if (!is_string($plaintext)) {1380            throw new SodiumException('Could not read input file');1381        }1382        $first32 = self::ftell($ifp);1383 1384        /** @var string $subkey */1385        $subkey = ParagonIE_Sodium_Core32_HSalsa20::hsalsa20($nonce, $key);1386 1387        /** @var string $realNonce */1388        $realNonce = ParagonIE_Sodium_Core32_Util::substr($nonce, 16, 8);1389 1390        /** @var string $block0 */1391        $block0 = str_repeat("\x00", 32);1392 1393        /** @var int $mlen - Length of the plaintext message */1394        $mlen0 = $mlen;1395        if ($mlen0 > 64 - ParagonIE_Sodium_Crypto::secretbox_xsalsa20poly1305_ZEROBYTES) {1396            $mlen0 = 64 - ParagonIE_Sodium_Crypto::secretbox_xsalsa20poly1305_ZEROBYTES;1397        }1398        $block0 .= ParagonIE_Sodium_Core32_Util::substr($plaintext, 0, $mlen0);1399 1400        /** @var string $block0 */1401        $block0 = ParagonIE_Sodium_Core32_Salsa20::salsa20_xor(1402            $block0,1403            $realNonce,1404            $subkey1405        );1406 1407        $state = new ParagonIE_Sodium_Core32_Poly1305_State(1408            ParagonIE_Sodium_Core32_Util::substr(1409                $block0,1410                0,1411                ParagonIE_Sodium_Crypto::onetimeauth_poly1305_KEYBYTES1412            )1413        );1414 1415        // Pre-write 16 blank bytes for the Poly1305 tag1416        $start = self::ftell($ofp);1417        fwrite($ofp, str_repeat("\x00", 16));1418 1419        /** @var string $c */1420        $cBlock = ParagonIE_Sodium_Core32_Util::substr(1421            $block0,1422            ParagonIE_Sodium_Crypto::secretbox_xsalsa20poly1305_ZEROBYTES1423        );1424        $state->update($cBlock);1425        fwrite($ofp, $cBlock);1426        $mlen -= 32;1427 1428        /** @var int $iter */1429        $iter = 1;1430 1431        /** @var int $incr */1432        $incr = self::BUFFER_SIZE >> 6;1433 1434        /*1435         * Set the cursor to the end of the first half-block. All future bytes will1436         * generated from salsa20_xor_ic, starting from 1 (second block).1437         */1438        fseek($ifp, $first32, SEEK_SET);1439 1440        while ($mlen > 0) {1441            $blockSize = $mlen > self::BUFFER_SIZE1442                ? self::BUFFER_SIZE1443                : $mlen;1444            $plaintext = fread($ifp, $blockSize);1445            if (!is_string($plaintext)) {1446                throw new SodiumException('Could not read input file');1447            }1448            $cBlock = ParagonIE_Sodium_Core32_Salsa20::salsa20_xor_ic(1449                $plaintext,1450                $realNonce,1451                $iter,1452                $subkey1453            );1454            fwrite($ofp, $cBlock, $blockSize);1455            $state->update($cBlock);