
Unless there has been a _major_ change in the law, there's no such beast
as a "classified patent."  Patents exist to encourage communications and
develop the state of the art. 

(The 17-year lock is a nuisance, but historically has been pretty trivial.
It's only in an industry which doubles performance every three years (or
18 months, for some hardware) that 17 years is an eternity).

The same thing applies in civilian development: you can't patent something 
_and_ declare it a "trade secret."  However, you can (and should) mark all
software (including proprietary code) "unpublished copyright" so that it
ever does get exposed you still have some legal protection.

(Post-Berne this isn't required, since everything is "born copyrighted."
But it takes a while for people to learn the new rules).
