Well, reality is not black & white here: We as Nitrokey open-source nearly all development efforts. Nevertheless we have to use components that are not (entirely) open-source, the OpenPGP SmartCard Applet is open-source btw.: https://github.com/Nitrokey/openpgp-card/ ... ZeitCard/BasicCard OS provides various means to audit/review their crypto functions, but various components are under NDA - it's still (patented) crypto and semi-conductor-layout material. If you know of a "more" open-source-ish solution, feel free to point us there...