The only way to block botnets from CPU mining a coin would be to implement some physical access lock into the software. For example a USB thumb drive that contained a signature of some sort.
So it will be closed source then. Red flag.
I don't follow your logic, why would it need to be closed source to implement this? The idea was that people running botnets or VPS farms don't have physical access to their machines. So in order to block them from mining a coin you need to implement something that requires physical access. Like inserting a usb key, with a
publicly available signature loaded on to it, into the computer.
edit: ah i see my flaw now, and why you said closed source. I guess if it was open source someone could just comment out that check and run the coind anyway. hmmm....
edit edit: I still think it's possible actually. I think you would have to just make the string that the thumb drive delivers part of your algorithm. So it couldn't simply be removed from the code.