Estoy tratando de comprimir los datos usando la biblioteca zlib .net. Independientemente del contenido de la cadena sin comprimir, parece que solo obtengo dos bytes de datos en bruto [].

{
    string uncompressed = "1234567890";
    byte[] data = UTF8Encoding.Default.GetBytes(uncompressed);

    MemoryStream input = new MemoryStream(data);
    MemoryStream output = new MemoryStream();
    Stream outZStream = new ZOutputStream(output,zlibConst.Z_DEFAULT_COMPRESSION);

    CopyStream(input, outZStream);

    output.Seek(0, SeekOrigin.Begin);
    byte[] raw = output.ToArray();
    string compressed = Convert.ToBase64String(raw);
}

public void CopyStream(System.IO.Stream input, System.IO.Stream output)
{
    byte[] buffer = new byte[2000];
    int len;
    while ((len = input.Read(buffer, 0, 2000)) > 0)
    {
       output.Write(buffer, 0, len);
    }
    output.Flush();
}