In fact, I am quite curious if there is a certain connection between Kirkhoffs law and opensource software (well, open-idea-software, but giving out ideas is almost as good as giving out source, but giving out source definately is more than giving away an idea). Recall, Kirkhoff's law dictates that the security of a cryptosystem must not depend on the secrecy of the system itself, but on the secrecy of the key's involved (and probably P != NP). And now, remember again: There are some ridiculous well-going open source programs (linux, gcc, ...) and even more, there are certain really well going commercial open source systems (such as mysql). Thus, I am pretty curious, if there is a similar kirkhoffs law for software (as in: the commercial success of a software can be achieved even without keeping the source secret, or something similar).