Histories of Cryptography and Cryptography Declassified, Sort of

[Metavox LLC]

Much has been redacted but there is still a lot of interesting material. 
  Per some discussions at tacos today I am posting this.

History of Cryptography
http://www.governmentattic.org/2docs/Hist_US_COMSEC_Boak_NSA_1973.pdf

History of Cryptology

Spartans in Darkness: American SIGINT and the Indochina War, 1945-1975
http://www.fas.org/irp/nsa/spartans/spartans.pdf

Multivolume history of Cryptology at the NSA:
  http://www.gwu.edu/~nsarchiv/NSAEBB/NSAEBB260/
the linked page gives a summary, but the 6 trigonal documents are 
available on this page to download.

you may also want to look at some of the other documents at the National 
Security Archive:
http://www.gwu.edu/~nsarchiv/index.html

Frank K0BRA