OT:decoding enigma (was Re: One of only 3 "enigma machine" stolen;

From: Geoff Roberts <geoffrob_at_stmarks.pp.catholic.edu.au>
Date: Wed Apr 5 02:51:08 2000

----- Original Message -----
From: "Sean 'Captain Napalm' Conner" <spc_at_armigeron.com>
To: <classiccmp_at_classiccmp.org>
Sent: Wednesday, April 05, 2000 3:02 PM
Subject: Re: OT:decoding enigma (was Re: One of only 3 "enigma machine"

> It was thus said that the Great Geoff Roberts once stated:
> >
> > 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
> > U-boat they had forced to
> > surface after prosecuting it with depth charges.
> In Neil Stephenson's _Cryptomonicon_,

Heard of it, haven't read it. Must see if I can round up a copy.

> half the story takes place during
> WWII in which the Allies are breaking the Axis codes and sending one
of the
> main characters on wild missions that mainly deal with being seen.
> As one of the characters says, ``The object of an observation plane
isn't to
> observe, but to be observed.''

Sometimes, perhaps, but I must differ with you on that point. Early in
the war, it was remarked that the side with the best photographic
intelligence would win. The British (somewhat reluctantly at first)
developed the essentially WW1 cameras and aircraft into an excellent
system, not only of obtaining good quality pictures, but performing a
careful and detailed analysis of them. Much of what was known about
Peenemunde and the V1/V2 projects that emanated from it was gleaned from
Photo reconaissance, with hints from Ultra at times.
Numerous other examples, (the finding of the Tirpitz for instance) also
were a direct result of PR.
German radar was first identified in a photo taken (using a hint from an
intercepted Enigma message) which ultimately resulted in a low-level (PR
pilots referred to it as 'dicing') run past a "Freya" on the French
Later PR work found the installation at Bruneval that was subsequently
raided, and parts and staff captured, by a small force of British
commandos. Models of the site and it's approaches were built up using
extensive PR 'cover' of the area. It's probably fair to say that the 2
had a symbiotic relationship, PR being used to confirm, expand or
capitalise on the Ultra intelligence. It's known that the Chief
Scientific Advisor to Winston Churchill considered it impossible for
anything like the V2 to be built, as the weight of the vehicle strong
enough to contain sufficient cordite would exceed it's lifting ability.
(This is before liquid fuelled rockets were considered practical on a
large scale). Despite 'Ultra" traffic to the contrary, his stand was
overturned with the help of PR cover of Peenemunde presenting visible
evidence, on top of Ultra traffic, sufficient to convince Churchill.
Had this not occured, it is possible the German development and
deployment program would have been significantly unhindered, which could
have had serious consequences for the Allies. The successful detection
and prosecution of the V1 'Ski sites' in France was almost entirely a
result of PR interpreters noting the construction of the buildings and
lauching ramps, which in the first stage, were quite large and served by
a rail spur. Destruction by bombing of the large scale ski sites led
the Germans to construct a smaller, less conspicuous site, with only a
couple of essential structures. These too were found, though not all
were destroyed.
"For want of a nail......"

The British pioneered the practice of using a single high performance
fighter, stripped of guns and other additional weight and drag adding
items, painted so as to make it hard to see against the sky. Such an
aircraft could outrun enemy fighters, and was able to operate (and take
useable pictures!) well above the accurate range of AAA of the time.
High altitude presented it's own problems, and required such things as
ducting warm air over the cameras and lenses to stop them freezing or
frosting over in the subzero temperatures. TheGermans began to adopt
similar techniques later in the war, (the Arado jet bomber was used for
PR at one time).

The German's had a somewhat fanciful notion of the excellence of British
Intelligence, (it was good, but not THAT good) and put down some
seemingly 'clairvoyant' actions by the enemy to spies and other
'conventional' sources of information. They apparently did not at
anytime suspect that Enigma had been penetrated. (Though I believe the
question was asked of the Intelligence service at one time.)
Considering the security wrapped around BP and it's "Ultra" traffic,
this is not surprising.


The existence of the Colossus machine (used to penetrate the
Geheimschreiber codes) was still secret for many years after WW2. The
first true computer, it predated the Eniac and other things by some
years, but it's existence was so shrouded in secrecy, it was over 30
years before it became public knowledge.
A working replica has recently been created at Bletchley, and fairly
recently, the plans for the Bombe decoding machines used to penetrate
Enigma, (none survived the war, and the plans were thought to be
lost)were discovered in records of the British Tabulating Machine
Company who built them under highly secret conditions for BP. An
attempt is now being made to construct a replica of the Bombe.

(I'm probably preaching to the knowledgeable here, excuse me if you know
this already)


> You don't want to alert the other side that
> you've broken their code---otherwise they might change it on you.

For 'might' read 'will'. If a code is suspected of being compromised,
or even if a code or cypher book is lost (in the conventional sense) it
is invariably changed. The author of the book that contained the
reference to the U-boat incident remarked that it was probably fortunate
the U-boat sank under tow, (during the night IIRC) or it might well have
been spotted by a German aircraft, and the codes would doubtless have
been considered compromised and changed at once. No combatant would
risk using a compromised code.
Exception: If you know your code is compromised, but the enemy don't
know that you know, it can be useful for disinformation purposes.
Example: German agents were dropped into Britain. As far as is known,
they were all captured before they could send any useful information.
(One broke his leg in the parachute landing, and woke up in an English
hospital) The spies were given the option of death by firing squad, or
incarceration in a prison. The incarceration option was conditional on
thier sending information, in their own codes, as directed by their
captors. The V1 attacks on London were actually affected by this, as
the spies were directed to inform their masters that the weapons were
overflying London and impacting beyond it.
This caused the Germans to alter the autopilot settings on the V1's so
that many that might have hit the city fell well short into (mostly)
uninhabited territory.


Geoff Roberts
Computer Systems Manager
Saint Mark's College
Port Pirie,
South Australia
ICQ: 1970476
Received on Wed Apr 05 2000 - 02:51:08 BST

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