Antonomasia wrote:
>
> "Arnold G. Reinhold" <[EMAIL PROTECTED]>:
>
> quoting David Kahn's "The Codebreakers" (1967):
>
> > "... the department budgeted $221,400 in 1964 for 650 KW-7's. ... The
> > per-item cost of $4,500 may be due in part to refinements to prevent
> > inductive or galvanic interaction between the key pulses and the
> > plaintext pulses, which wire tappers could detect in the line pulse
> > and use to break the unbreakable system through its back door. "
> >
Nah, I just think they were expensive.
> > This would be the electro-mechanical equivalent of TEMPEST and
> > suggests that NSA was well aware of the compromising potential of
> > incidental emanations long before the computer communications era.
>
> This seems to refer to the problem of sending key and/or plaintext
> alomg the communications channel intended to carry only ciphertext.
> I seem to remember reading that this allowed allied reading of East German
> cable messages tapped in the 1950s (operation Prince ? Karlshorst tunnel
TEMPEST (NACSIM-5001) was intended to to prevent 'compromising
emanations', including classified information leaking on encrypted links.
This is the basic RED/BLACK separation. The rest is filtering, in general
sufficient to meet FCC Part A.
The KW-7/TSEC had an ancilliary interface unit that provided additional
filtering, but I don't believe it was available in 1964. The biggest
impact to low baud rate secure teletype systems was the the use of
MIL STD 883B (low voltage, low current signalling roughly compatible
with RS-232, although operating at +/- 6 Volts). Originally Teletypes
used 60 milliamp current loops and mechanical relays. The result
was enormous inductive spikes that could be detected at significant
distances from the plaintext (RED) TTY. The current value was dropped
to 20 MA. Eventually solid state relays were adopted based on cost.
Another piece of equipment of the same era, the KG-13/TSEC (and various
derivitives), had been modified by adding filtering modules and a 883B
interface in a module on the back. There was a separated compartment
for RED and BLACK interfaces, and the BLACK interface contained an
AC power filter.
For those who have subscribed to 'Electronics' or 'Signal' over the
years, you may have noticed a general lack of advertisements for
TEMPEST tested equipment. This is in part due to requirements for
SCIFs and TEMPEST waivers for intelligence end users. TEMPTEST
certifying is expensive, even more so than FCC/CDE, etc compliance
testing, although roughly equivalent. The paper trail is probably
reminiscient of aircraft parts. FIPS-140-1 is borrowed in part
from the COMSEC audit for cryptographic systems. Throughout the
history of COMSEC equipment, maintenance persons were forbidden
the use of uncertified replacement parts, although from the mid
'70s National Stocking Number parts in the Federal Supply System
were crossed to unclassified components. Today, COMSEC equipment
is all repaired at depots.
I still have my DD-1435.
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