return doHash(inputStream, outputStream);
    }

    private HashCode doHash(InputStream inputStream, OutputStream outputStream) throws IOException {
        byte[] buffer = takeBuffer();
        try {
            PrimitiveHasher hasher = Hashing.newPrimitiveHasher();
            hasher.putHash(SIGNATURE);
            while (true) {
                int nread = inputStream.read(buffer);