But who would have thought that trying to obtain information about information the agency has already given us would lead to the same wall?

That's what happened when the Federation of American Scientists filed a FOIA request with the Defense Department (of which the NSA is a part) earlier this year seeking information about any authorized leaks of intelligence made to the media during the previous 12 months.

The response they got (.pdf) from the National Security Agency might well have come from Winston Smith's Ministry of Truth.

"The document responsive to your request has been reviewed by this Agency as required by the FOIA and has been found to be currently and properly classified in accordance with Executive Order 13526," the letter read. "The document is classified because its disclosure could reasonably be expected to cause exceptionally grave damage to the national security."