The short answer to your question is that you CAN have a bootloader that "secures" the chip so it can not be dumped - only bulk erased.
The longer reply is that you may have to put a lot of work into getting that into place.
The standard bootloaders available AND the process of updating your code via the bootloader may not make that easy to implement.
Good luck.
Joe
.png "rohitchudasama"){kind=avatar}
