"How could it even get funding otherwise?"
Defense Department.
Just found this!
Now I know the writer is full of crap!
"The NRO and NSA are funded through the Defense Department and report directly to the secretary of Defense."
And this from the 'Democratic Leadership Council' no less.
http://www.dlc.org/ndol_ci.cfm?kaid=124&subid=900019&contentid=3929
NSA has been a Defense Agnecy under DoD for as long as I can remember. Head of NSA reports to Don Rumsfeld and he is usually from one of the four military branches. The NSA follows all of the DoD procurement regulations and their budget is through DoD (and other black budgets). See here Department of Defense (DoD)