WordPoints / wordpoints

         */

        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 Error('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;

        }

        try {

            ParagonIE_Sodium_Compat::memzero($block0);

            ParagonIE_Sodium_Compat::memzero($subkey);

        $incr = self::BUFFER_SIZE >> 6;

        /* Decrypts ciphertext, writes to output file. */

        while ($mlen > 0) {

            $blockSize = $mlen > self::BUFFER_SIZE

                ? self::BUFFER_SIZE

                : $mlen;

            $ciphertext = fread($ifp, $blockSize);

            if (!is_string($ciphertext)) {

                throw new Error('Could not read input file');

            }

            $pBlock = ParagonIE_Sodium_Core_Salsa20::salsa20_xor_ic(

                $ciphertext,

                $realNonce,

                $iter,

                $subkey

            );

            fwrite($ofp, $pBlock, $blockSize);

            $mlen -= $blockSize;

            $iter += $incr;

        }

        return true;

    }