Phil Sp. writes "Government Attic, those fine investigative pack rats, have outdone themselves this time. Just posted: a declassified NSA document entitled A History of Communications Security, Volumes I and II: The David G. Boak Lectures [PDF] from 1973 and 1981. This is an absolutely fascinating look into how the NSA viewed (views?) communications security and touches on all sorts of topics, including public key crypto, economics, DES, tamper-resistance, etc. It was seemingly from a collection of lectures to new employees. The first 85 pages are heavily redacted but the remaining 80 or so are largely intact. It even concludes with a cryptogram puzzle for the reader!"