Everything is possible. Cloning whole chip is probably economically not viable, but definitely possible (it's cheaper to design from scratch with modern automa

Everything is possible. Cloning whole chip is probably economically not viable, but definitely possible (it's cheaper to design from scratch with modern automatic design tools), but retrieving secret keys is a popular task. For a company having all the tools (electron microscope with bells and whistles, polishing machines, microprobes) it might take hundreds to thousands of human-hours (0.1-1+ million $). Companies like http://www.chipworks.com/ http://www.chipworks.com/ can do that, if your request is legal.