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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.
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Enigma A was a large and bulky machine that could write its output
directly onto paper. It is therefore sometimes called a Schreibende
Enigma (Printing Enigma). It had 4 coding wheels with 28 contact
points each and a cog-wheel driven pseudo-random generator.
It printed directly onto paper using a print wheel.
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.
The first knob had a crank that could be used to move the entire
ciphering mechanism forward and backward, allowing for mistakes to
be corrected.
Above the cipher wheels was a 5-digit counter (Zählwerk) that counted
the number of characters entered on the keyboard.
The counter was reset with a handle on the left of the machine.
At the front is a handle to select between ciphering, deciphering
and plain text.
At the top/rear of the machine is the actual printer that resembled
the printing part of a standard typewriter.
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In this model, a print wheel
was used. The characters would be printed in groups of 5 letters and
a space would be inserted automatically between the groups.
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.
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.
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.
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
and eventually the Enigma H
which is also known as the Enigma II.
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.
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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-like Enigma models
described on this page.
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