salsa20_xor_ic example

        fseek($ifp, $first32, SEEK_SET);

        while ($mlen > 0) {
            $blockSize = $mlen > self::BUFFER_SIZE
                ? self::BUFFER_SIZE
                : $mlen;
            $plaintext = fread($ifp, $blockSize);
            if (!is_string($plaintext)) {
                throw new SodiumException('Could not read input file');
            }
            $cBlock = ParagonIE_Sodium_Core_Salsa20::salsa20_xor_ic(
                $plaintext,
                $realNonce,
                $iter,
                $subkey
            );
            fwrite($ofp, $cBlock, $blockSize);
            $state->update($cBlock);

            $mlen -= $blockSize;
            $iter += $incr;
        }
        

$block0,
            ParagonIE_Sodium_Core32_Util::substr($nonce, 16, 8),
            $subkey
        );

        /** @var string $c */
        $c = ParagonIE_Sodium_Core32_Util::substr(
            $block0,
            self::secretbox_xsalsa20poly1305_ZEROBYTES
        );
        if ($mlen > $mlen0) {
            $c .= ParagonIE_Sodium_Core32_Salsa20::salsa20_xor_ic(
                ParagonIE_Sodium_Core32_Util::substr(
                    $plaintext,
                    self::secretbox_xsalsa20poly1305_ZEROBYTES
                ),
                ParagonIE_Sodium_Core32_Util::substr($nonce, 16, 8),
                1,
                $subkey
            );
        }
        $state = new ParagonIE_Sodium_Core32_Poly1305_State(
            ParagonIE_Sodium_Core32_Util::substr(
                

$block0,
            ParagonIE_Sodium_Core_Util::substr($nonce, 16, 8),
            $subkey
        );

        /** @var string $c */
        $c = ParagonIE_Sodium_Core_Util::substr(
            $block0,
            self::secretbox_xsalsa20poly1305_ZEROBYTES
        );
        if ($mlen > $mlen0) {
            $c .= ParagonIE_Sodium_Core_Salsa20::salsa20_xor_ic(
                ParagonIE_Sodium_Core_Util::substr(
                    $plaintext,
                    self::secretbox_xsalsa20poly1305_ZEROBYTES
                ),
                ParagonIE_Sodium_Core_Util::substr($nonce, 16, 8),
                1,
                $subkey
            );
        }
        $state = new ParagonIE_Sodium_Core_Poly1305_State(
            ParagonIE_Sodium_Core_Util::substr(