[GreenKeys] Slightly OT - Churchill War Room

[Doug Hensley]

​I'll stand corrected and look to see where I got this information.  I did
not mean to mislead anyone.

Reading historical notes & web claims is risky at times 🙂 ...

Have a good week,

Doug W5JV




________________________________
From: David I. Emery <die at dieconsulting.com>
Sent: Sunday, March 31, 2019 2:44 PM
To: Doug Hensley
Cc: Keith Lueck; greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] Slightly OT - Churchill War Room

On Sun, Mar 31, 2019 at 03:31:27PM +0000, Doug Hensley wrote:
> Sigsally voice encryption predates functional teletype encryption.  It was that
> technology that allowed Allied leaders to direct war planning in Europe as well
> as enjoy readily available conference calls while teletype was coming up to speed.


        Others have already noted that this is not true.   There were a
number of TTY crypto systems in use in WW II - many off line ones, but
also on line including the still completely secure one time "pad" XOR
tape systems and others.   Some of the off line systems could read
punched tty baudot code tapes with streams of 5 letter groups and
convert that to messages... and print them - at least in the form of
glue on paper strips if not page printing.

        It would probably be reasonable to assume that with much of the
long distance strategic traffic flowing over noisy HF RTTY circuits in
WW2 that making the kind of synchronous bit stream encryption by a key
stream that became common later work with technology available of the
day was difficult because of data errors and loss of sync.  Punching
encoded messages from regular ITC RTTY signals in the form of strings of
5 letter groups into tapes that could be edited to handle garble from
static crashes and so forth made a lot of sense from a crypto sync
perspective.  Even if every character in the cipher text wasn't correct
one could at least ensure that there were the right number of them and
for many encyption algorithms (especially rotor ciphers) that  ensured
that only one character of plain text would get garbled for each bad
character of ciphertext - often tolerable especially if someone retyped
and reformated the resultant message for delivery.

        And of course the Germans also used on line tty encryption
(Lorenz Tunny) that Bletchley park broke (the actual system that
Collusus was built to attack)... one of the most important cryptologic
triumphs of the later part of WWII since Hitler used that system to talk
to his  generals a lot.

        It is also a well known bit of trivia that in the early to
middle part of WWII before the Sigsaly system was deployed Washington to
London high level radio voice communications were scrambled by speech
inversion and sub band swapping and the Germans apparently learned how
to use early magnetic tape technology to successfully break this and
recover FDR to Churchill calls.

        I too have been to the Churchill war rooms in London, and there
was relatively little communication gear such as TTY machines on display
there when I last visited.   One suspects there was a comm center
somewhere else  and most messages were brought in by messenger...
in those famous red boxes.

--
  Dave Emery N1PRE/AE, die at dieconsulting.com  DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in
celebration of what could have been, but wasn't and is not to be now either."

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