Interesting point about the declassified Capstone spec

[Peter Gutmann]

Late last year the Capstone spec ("CAPSTONE (MYK-80) Specifications",
R21-TECH-30-95) was partially declassified as the result of a FOIA lawsuit[0]. 
The document is stamped "TOP SECRET UMBRA" on every page.  UMBRA is a SIGINT
codeword, not an INFOSEC one, so the people who designed the thing were very
clear about what it was to be used for at a time when it was still being touted
as a privacy device (the fact that it's described in the abstract as "a SIGINT
friendly replacement for DES" probably doesn't help either).

Peter.

[0] I don't know if it's online, they were handed out at Crypto'99.