The Air Force and DoD probably do have a lot of useful data on high altitude hypervelocity deployment of parachutes and re-entry systems, but a lot of it is restricted, for obvious reasons.

Also, much does not apply particularly to the very different atmosphere, gravity, and rentry profile for Mars, and the different mass and volume of a Mars lander vs something else.

And, in the same way that the Apollo heritage has effectively been lost through retirement of that cohort of the workforce, and changing materials technology, so too is much of the military technology already obsolete and effectively irrecoverable, even while it remains classified.

(That doesn't mean it's silly to still classify it. It would still give too many good ideas to someone with a malicious intent!)