The 'steal plans' action would certainly be influenced by that, in both directions: If the defender has the code advantage, it could become impossible for the spy to steal plans without (perhaps) a very lengthy preparation - the spy basically has to learn about the code and has to subject himself to intense scrutiny to get that kind of education. If the knowledge difference gets too great, it just isn't possible anymore.
Then there is also the use of code on the battlefield, which could enable commanders to exert much more control over units even at some distance. If broken, that effect is undone or perhaps slightly negated if the commander doesn't know the code is broken.
Edit: Perhaps a civic-dependent paranoia value would make sense.
Then there is also the use of code on the battlefield, which could enable commanders to exert much more control over units even at some distance. If broken, that effect is undone or perhaps slightly negated if the commander doesn't know the code is broken.
Edit: Perhaps a civic-dependent paranoia value would make sense.