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First Enigma machine
The Enigma A is the very first cipher machine sold under the Enigma brand.
It was developed by the company Scherbius & Ritter of Berlin-Wannsee (Germany), but was put into production by Gewerkschaft Securitas
(later: Chiffriermaschinen AG), also of Berlin.
As far as we currently know, there are no surviving samples of the Enigma A.
The machine was succeeded by the Enigma B.
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Enigma A was a very heavy and bulky machine that could write its output
directly onto paper. It is therefore sometimes called a Schreibende
Enigma (Printing Enigma). The description below was taken from an
article by the inventor Arthur Scherbius in a technical magazine in 1923 [1].
The machine featured 4 coding wheels with 28 electrical contact points each,
and a cog-wheel driven transport mechanism. Each cog-wheel had a different
number of teeth (using prime numbers and numbers without a common factor)
in order to guarantee a long cipher period and irregular (i.e.
less predictable) stepping [2].
The four cipher wheels were fitted permanently inside the machine
and their starting position could be set with four knobs at the right.
By pulling out each knob, the position of the driving (notched)
cog-wheel could be also altered.
A fifth knob at the top was connected to the main transport axle.
By inserting a crank into this knob, the entire ciphering mechanism
could be moved forward and backward, which was intended for the
correction of mistakes.
Above the cipher wheels was a 5-digit counter (German: Zählwerk)
that counted the number of characters entered on the keyboard.
The counter was reset with a handle sticking out in the left.
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As the ciphering operation was not reciproke (i.e. reversible),
a handle was present at the front of the machine to select
between ciphering, deciphering and plain text.
When switching between ciphering and deciphering, the current through
the coding wheels is reversed. When the handle is set to plain text,
the machine can be used as an ordinary typewriter.
At the top/rear of the machine is the actual printer that resembles
the printing part of a standard typewriter of the era. It consists
of a paper carriage and a wheel printer.
The characters would be printed in groups of 5 letters and
a space would be inserted automatically between the groups when
creating cipher text. 10 such groups fitted on a single line
(50 characters), after which the user manually had to return the
carriage to the start of a new line.
When deciphering, spaces would be inserted automatically where appropriate,
so that the text was immediately legible.
The keyboard contained numbers, letters and a spacebar. A plain text
message could contain a mixture of these, and Shift-keys were used
to toggle between letters and figures.
The cipher text however, would only contain letters as the cipher
wheels only had 28 contacts each. The reason for this is that it
makes the makes the message shorter, as in the
morse alphabet
letters are substantially shorter than numbers [1].
The Enigma A featured a complex cog-wheel driven wheel turnover
mechanism with irregular stepping.
Each cipher wheel had a large cog-wheel attached to its right side,
driven by a set of smaller cog-wheels (each with a different
diameter) from which a number of teeth were missing.
According to Scherbius, it had a cipher period of approx. 1 million,
which means that the cipher pattern repeats only after 1 million
characters. About 20,000 of such periods were present.
Part of the wheel turnover mechanism is described
in patent DE429122
of 26 March 1924 [2].
At this time we don't have access to better images of the Enigma A.
The pictures shown on this page were taken from a detailed description
of the machine by Arthur Scherbius himself in Elektrotechnische
Zeitschrift (Electro-technical Magazine) in 1923.
In 2008 we found this magazine at an antiques shop in Germany.
The full article can be downloaded below.
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Newer models and improvements
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The Enigma A was developed and introduced in 1923.
Due to reliability problems with the print wheel mechanism,
it was soon replaced by the Enigma B
that featured commonly used type bars (German: Typenhebel).
After several improvements, the Enigma B was replaced in 1929
by the Enigma H
which is also known as the Enigma II.
It uses shift-bars instead of normal type-bars.
A year after the introduction of the Enigma A, the company also released
the first Glühlampen-maschine (lamp machine),
the Enigma C, with was much smaller, far less heavy
and above all much cheaper. Although the lamp-based machine was technically
far less advanced than the printing variants, it was far more successful
and eventually evolved into the Enigma I
that became the mainstream cipher machine of the German Army during WWII.
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Please note that the name Enigma A sometimes leads to confusion.
As the early lamp-based Enigma machines C, D, G, K and I (Wehrmacht)
initially all had serial numbers starting with the letter 'A',
these machines are sometimes (wrongly) called Enigma A.
Even during WWII, the Enigma I machines used by the Wehrmacht
and Luftwaffe sometimes had serial numbers starting with the
letter 'A'.
The name Enigma A
should only be used for the first typewriter-style Enigma models
described on this page.
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At this time, no further information about the Enigma A is available to us.
It is likely that only a few were ever built.
As far as we know, there are no surviving samples of this machine.
If you have additional information about this machine, please
contact us.
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© Copyright 2009-2013, Paul Reuvers & Marc Simons. Last changed: Monday, 11 February 2013 - 00:14 CET
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