Glossary
Open Design
Open design holds that a system's security shouldn't depend on attackers not knowing how it works — the design can be public and reviewed, and the actual protection should come from secrets like keys that are genuinely hard to obtain, not from obscurity about the mechanism itself. A design that only holds up as long as nobody examines it closely hasn't really been shown to be secure at all; it's simply untested.
This favors designs that can withstand scrutiny, including scrutiny from an adversary who fully understands how the system works, over designs whose safety depends on that understanding never reaching the wrong hands. A design good enough to survive public review is also one whose flaws get found by defenders reviewing it, rather than only by attackers who stumble onto them first.