5 Jan
2012
5 Jan
'12
6:50 p.m.
On 2012 Jan 5, at 12:50 PM, Colin Eby wrote:
Brent,
As it happens I also put in a visit to this museum over the holidays.
The SIGSALY display is a model rather than the real gear. I don't know
how much of the original gear they might have in the vaults, but it's
not what's displayed. They use models in a number of places -- mostly
to good didactic effect. For a hardware connoisseur it would be a bit
disappointing other than to see how it was all racked. I have a
photo of
it if you're interested.
Oh.. well it's quite the mock-up then (there are some pics on the web
site). I think the NSA museum site said what was on display was a
'portion' of one system. For my part, I'm more interested in
technical details and the system design. There is some technical
description at one of the links I mentioned below
(sigsaly_start_digital), but it still left a few questions about the
design and requirements.
On Tue, 2012-01-03 at 15:31 -0800, Brent Hilpert
wrote:
On 2012 Jan 3, at 12:30 PM, Mark Kahrs wrote:
-- Colin Over the break I visited the NSA's museum
(just a stone's throw
from Ft.
Meade). For those who like crypto machines, it is definitely,
definitely
worth a visit. The curators and staff are very enthusiastic (they
even
brought out a machine from the back vault) and of course you can
buy an NSA
t-shirt if your heart desires. They had a mix-up with the Y-MP
processor
board and memory board on display (I told them) but otherwise it's
fun just
to see a Cray I up-close-and-personal. They have the tape jukebox
being
run from a PC. And the CM is flashing lights, but that's about
it. The
modern crypto gear is shown but the commentary is sparse at best.
(In case
you're wondering, the boxes are empty -- so I was told). There is
little
mention of public key cryptosystems. Or controversial questions
like key
length or key escrow.
But worth a detour? Definitely.
Did you see the SIGSALY display (aka "X System")? Haven't been to the
crypto museum myself, but I was reading about SIGSALY recently, and
see they have some of the equipment (http://en.wikipedia.org/wiki/
SIGSALY).
Real-time voice cryptography using pulse code modulation and digital
algorithms and technology in WWII:
http://www.nsa.gov/about/cryptologic_heritage/
center_crypt_history/
publications/sigsaly_start_digital.shtml
http://www.nsa.gov/about/cryptologic_heritage/
center_crypt_history/
publications/sigsaly_story.shtml
Reading about it, I could see the technological ability to do it at
the time, but I had no idea until recently it had actually been done
at the time!
Shannon had some involvement in its development, just a couple of
years before his papers on information theory. The historical
connections and influences make for very interesting reading:
http://dspace.mit.edu/handle/1721.1/39429?show=full
(download PDF from there)
The paper by Lars Lundheim 'On Shannon and "Shannon's Formula"'
http://www.iet.ntnu.no/projects/beats/journals.htm
is also interesting for some historical developments leading to
information theory, including the concepts of sampling and digitising
analog data, see mention of Alec Harley Reeves.