ParagonIE\Halite\File::streamEncrypt PHP Method

    private static final function streamEncrypt(ReadOnlyFile $input, MutableFile $output, EncryptionKey $encKey, string $nonce, string $mac, Config $config) : int
    {
        $initHash = $input->getHash();
        // Begin the streaming decryption
        $size = $input->getSize();
        $written = 0;
        while ($input->remainingBytes() > 0) {
            $read = $input->readBytes($input->getPos() + $config->BUFFER > $size ? $size - $input->getPos() : $config->BUFFER);
            $encrypted = \Sodium\crypto_stream_xor($read, $nonce, $encKey->getRawKeyMaterial());
            \Sodium\crypto_generichash_update($mac, $encrypted);
            $written += $output->writeBytes($encrypted);
            \Sodium\increment($nonce);
        }
        \Sodium\memzero($nonce);
        // Check that our input file was not modified before we MAC it
        if (!\hash_equals($input->getHash(), $initHash)) {
            throw new FileModified('Read-only file has been modified since it was opened for reading');
        }
        $written += $output->writeBytes(\Sodium\crypto_generichash_final($mac, $config->MAC_SIZE), $config->MAC_SIZE);
        return $written;
    }