Recently I was skimming through the NSA's "classified history of COMSEC" (posted at governmentattic.com)
. This "history" is a transcription of lectures by David G. Boak, who liked to explain NSA-related topics from a historical perspective. He clearly inspired a generation of NSA's employees. The last "real" page of the document contains a humorous story and a crypto puzzle (link to pdf)
The NSA had an incinerator in their old Arlington Hall facility that was designed to reduce top secret crypto materials and such to ash. Someone discovered that it wasn't in fact working. Contract disposal trucks had been disposing of this not-quite-sanitized rubish, and officers tracked down a huge pile in a field in Ft. Meyer.
How did they dispose of it? The answer is encrypted in the story's text!
The story sounds like it's from the early 1960s. The Arlington Hall incinerator contained a grating that was to keep the documents in the flames until reduced to ash. The grate failed, and "there was no telling how long the condition had persisted before discovery."
Contract haulers had been dumping the stuff "in abandoned clay pits in Fairfax County" and NSA investigators never found them.
For those of you familiar with Farifax County today, it may seem hard to believe that there were "abandoned" chunks of land anywhere. I grew up in the 'wilds' of that area back then, and believe me, there were places that seemed pretty remote from civilization.
At any rate, the investigators did manage to track down a couple huge piles of ashes over at Ft. Meyer - about 1,000 cubic yards of the stuff. And here's the puzzle: the action officer tasked with handling the mess came up with a simple and brilliant strategy - cost effective at the time but probably not any more. What was it?
The Puzzle - Possible Cribs
Boak encrypted the answer in an "innocent text system" in the story's text itself.
I haven't actually tried to crack the code yet myself. First, I'm racking my brain for strategies of how the disposal might work. Here are some ideas:
- Dump it in the Potomac - this was back when conservationsts were mostly cranky scientists, agricultural experts, and a few youthful geeks.
- Dump it in a more salty place - the Chesapeake or the Atlantic.
- Mix it with cement and use it as a foundation for the Capital Beltway - the incident apparently happened around the time of Beltway construction.
- Ditto, but pour it into cement foundations for new CIA headquarters being built in nearby McLean, or perhaps for a classified building elsewhere. Ft. Meade, perhaps?
- Ditto, but use it in construction of the Greenbrier Bunker in West Virginia.
The fundamental problem is to keep control of the readable chunks. While most of the material was ash, there were "palm sized" chunks of waste that might disclose information. Whatever they did, they had to ensure those chunks were unreadable, or at least safe from disclosure.
I like the cement idea, actually. No doubt there were cleared construction crews all over the Washington area back then. Temporary structures littered the Mall, most of them built during WWII, and many housed intelligence agencies. They were all gone in the next several years as the occupants moved to newly built, more secure locations.
Some of these construction tasks were sensitive enough to demand some clearances from the construction crews: CIA headquarters, the Greenbrier Bunker, and no doubt Ft. Meade had projects underway, too. Personally, I'm not aware of the construction dates up at Ft. Meade - it wasn't part of my youthful stomping grounds. But the CIA and the Greenbrier might fit the calendar.
If they used the stuff in the Beltway, they'd need to send officers to ensure that no readable chunks were pulled out by workmen. I doubt any clearance effort went into Beltway construction crews.