Category Archives: Security

Boak’s Puzzle: Disposing of Classified Trash

Boak's History of US COMSECRecently I was skimming through the NSA’s “classified history of COMSEC” (Volume 1 and Volume 2).  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 extract in 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! Continue reading Boak’s Puzzle: Disposing of Classified Trash

Real-world document encryption

I’ve been reviewing histories of cryptography recently and here’s an interesting thing about pre-computer encryption: it’s almost entirely used for communications security. People encryptedmessages, but they rarely encrypted documents.

I’ve finally found a few real-world cases: encrypted diaries. BBC did a short segment on them last summer. But I’m still looking – there must be other cases where someone needed to keep some long-term data secret from prying eyes.

Continue reading Real-world document encryption

Design Patterns for Identity Systems

These are design patterns in the Christopher Alexander sense rather than the object oriented design sense: they address the physical and network environment rather than focusing on software abstractions. The patterns were introduced in my book Authentication.

There are four patterns: local, direct, indirect, and off-line.

Continue reading Design Patterns for Identity Systems

Fixing the Insider Threat: Separation of Duty

The insider threat isn’t easy to fix. We can fix it with Separation of Duty, but it requires planning ahead, discipline, and effort. But it’s essentially why banks can hire low-wage tellers and not worry about theft at the till (or at least not as much).

San Francisco lost control of their FiberWAN. It’s not clear how much this affected day to day operations, since the city appeared to still be working. And that in itself is a tribute to separation of duty.

Continue reading Fixing the Insider Threat: Separation of Duty