On Wed, 2006-11-22 at 10:37 -0700, Richard wrote:
So, googling for AN/UGC-74 seems to imply that this is
a "secure
teletype". It purports to talk Baudot code as well as ASCII. Does
anyone have any idea what makes it "secure"?
Yes. All video devices leak electromagnetic radiation. With the
proper equipment, a spy with a big budget can "read" the screen of a
computer in another room by the RF energy it puts out. A project called
"Tempest" produces terminals (or computers, or hybrids) which are
electronically shielded so well that the NSA's equipment cannot spy on
them.
I worked for a company that produced this kind of equipment,
although NOT the militarized version with the Army/Navy designation you
mention above. The bear of it is that the spec's you must meet are
classified at just about the most restrictive level there is. It's
called "read and commit suicide," or something. So, you take a shot at
it, and send in a prototype. You get back a "Yes" or a "No" as to
whether the prototype makes the grade, and no other information. If no,
keep trying 'til you run out of money. It's risky, but BOY does the
government pay a bundle for them when you get a prototype that works.
They also want a LOT of them. So, various companies keep trying, and
strike it rich if they happen to make one that works, or waste a metric
buttload of cash making prototypes that leak too much RF.
Peace,
Warren E. Wolfe
wizard at
voyager.net