OT:decoding enigma (was Re: One of only 3 "enigma machine" stolen; A piece of ENIAC was up for auction.)

From: Geoff Roberts <geoffrob_at_stmarks.pp.catholic.edu.au>
Date: Tue Apr 4 20:50:01 2000

----- Original Message -----
From: "Chris Kennedy" <chris_at_mainecoon.com>
To: <classiccmp_at_classiccmp.org>
Sent: Wednesday, April 05, 2000 12:27 AM
Subject: OT:decoding enigma (was Re: One of only 3 "enigma machine"
stolen; A piece of ENIAC was up for auction.)

> Hans Franke wrote:
> > For the records, Bletchley Park did not decode _all_ variants
> > used during the war - but they did a prety good job for most
> > of the stuff. The key was luck and a lot of good work.
> And some moderate sloppyness in traffic handling by the German
> command.

The Luftwaffe was particularly slack in this area, the Reichsmarine most
certainly were not.
The Railway system also used Enigma, to my knowledge, this was never
cracked, presumably
since it was mostly used on landlines.

> Different code schemes were used for different services, with
> perterbation of the code schemes based on sensitivitiy. As a
> consequence, the code schemes for the U-boat fleet were changed
> quite often, while the code scheme used for harbor dispatches
> remained static for prolonged periods of time.

The Enigma variant and the code used by the Unterseeboote branch
(Hydra?) was not penetrated
until the British were able to capture the Enigma and codebooks from a
U-boat they had forced to
surface after prosecuting it with depth charges.
The captain supposedly committed suicide (allowed himself to drown
according to the story)
when he realised he had not disposed of the Enigma and his code books,
and the boat didn't sink immediately.
ISTR that scuttling charges weren't set in the rush to get off the boat
before it sank, (damaged boats that made the
surface rarely stayed afloat for more than a minute or two, so this is
understandable) unfortunately for the
Germans, this one didn't sink straight away.
The enigma and codes were retrieved and this gave the the British the
ability to read
the U-boat traffic for the remainder of the 3 month's of the boat's
patrol. The boat was put under tow but
rolled over and sank before they got it back to England. IIRC, this
info was used to prosecute the 'Milch Cow'
supply submarines, many of which were successfully attacked and sunk
during this period. This had a serious
effect on the success of U-boat operations for that period. Things they
learned during this 3 month honeymoon
made it possible to penetrate the code again, using the same techniques
as with the other Enigma traffic, though it
did take some months before they were again able to read the U-boat
The Neptune and Triton codes used by the Reichsmarine were eventually
pentetrated by 'conventional' (for BP) means,
but not to the same extent as the Luftwaffe variants. IIRC, 'Ultra'
traffic led to the discovery and subsequent sinking of the
Tirpitz in a Norwegian Fiord. (With a significant contribution from a
British Photographic Recon Spitfire flown by Micheal Suckling)

References: Most Secret War by Professor R. V. Jones (WW2 head of
British Scientific Intelligence)
                    The Secret War (BBC TV series, made in the mid
80's, and the book of the series)
                    Evidence in Camera (Author's name escapes me for the
present, a WRAAF Officer)
                    Semi official history of the developement of Allied
Photo reconaissance in WW2
                    Doubtless several others I have read but can't
recall the titles of at the moment.

Geoff Roberts
Computer Systems Manager
Saint Mark's College
Port Pirie,
South Australia
ICQ: 1970476
Received on Tue Apr 04 2000 - 20:50:01 BST

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