Please note that there is no such thing as the Enigma.
Enigma is the brand name of a series of cipher machines,
developed before and during WWII,
some of which are compatible with each other,
and some of which are not.
If your are interested in the history of Enigma,
you might want to check
the Enigma Family Tree,
the Enigma Timeline, or
the Enigma Glossary.
Before and during WWII, Enigma was the inspiration for many
other designs of rotor cipher machines, such as the British
Typex and
the American SIGABA.
And even after the war, some cipher machines were based on the
same principle, such as the American KL-7,
the Russian Fialka and
the Swiss Nema.
We are always interested in acquiring new equipment, documents
and other artefacts for the museum.
If you have something to offer, please contact us.
Enigma is arguably the most well-known implementation of
the rotor-based cipher machine. As its patents were registered in various
countries,
many designs of similar machines were based on it.
Many of the later machines, including the machines that were used
by the Allied Forces during and after WWII,
were largely based on the design of the Enigma.
Here are some examples:
Many attempts have been made to describe the working principle of
the Enigma machine on the internet. Some of these are correct, and
some are not. This is yet another attempt.
Several years ago, when creating the Enigma-E,
an electronic replica of the Enigma,
we had trouble understanding the precise
operating principle of the Enigma machine;
something that is vital for a reliable simulation.
At the time, most websites only gave a rough description
of the machine and important details were omitted.
We then created out own description and made it publicly available.
➤More information ➤Wheel wiring
If you are interested in building your own electronic Enigma machine,
you might want to learn more about the Enigma-E
self-build kit.
It is compatible with a real Enigma machine.
A great animation on how the Enigma works is available below.
It was created in December 2021 by Jared Owen, and features Enigma I —
the most common Enigma model that was used by the German Army during
WWII. For more great
animations, visit Jared Owen's YouTube channel[3].
Before and during WWII, many different Enigma machines were
developed and built. Some of these machines are compatible with
each other, but others are not. Below is a list of some of these
machines that we've seen over the years. Please note that
this list is by no means complete and will be subject to future
changes, as and when we find 'new' machines.
Each machine is described briefly below.
Click the image for a full description with many photographs.
In 1923, the first machine under the Enigma brand appeared on
the market. It was known as Die Handelsmaschine,
and was large and bulky.
The machine resembled an electric typewriter and printed its output
directly on paper.
Although we've never actually seen the machine, and therefore
have no good photographs of it, we did find an
accurate description of the machine by inventor Arthur Scherbius himself.
Die schreibende Enigma was developed between 1924 and 1926,
as the successor to the Handelsmaschine.
The rotating print head of the earlier machine
was replaced by a series of type-bars, like the ones commonly
found on typewriters.
The machine looks very similar to a standard typewriter and is very well
finished. Nevertheless, there were many production problems and
it appeared very difficult to operate it reliably at higher printing
speeds.
Eventually, in 1929, it was replaced by the Enigma H
(see below) which was far more bulky.
The Enigma H was the last model in the range of Schreibende Enigma
(printing Enigma) machines. It was developed and introduced in 1929, as
the successor to the Die schreibende Enigma.
The official model number for this machines was H29 and the internal
designator was Ch. 14, whilst it was called
Enigma II by the Reichswehr (the predecessor of the Wehrmacht).
This machine was sometimes used as a printer for
a modified Enigma I
or Enigma G.
Enigma A was the first Enigma cipher machine that used light bulbs for its
output. It is therefore also known as the Glühlampenchiffriermaschine
(glow lamp cipher machine). It had a rather uncommon layout and required
a special key to be pressed in order to set the rotors in motion.
The machine was introduced in 1924 was soon succeeded
by its successor, Enigma B.
As far as we know, there are no surviving
examples of the Enigma A.
The Enigma B was the second machine that used light bulbs (Glühlampen)
for its output. It was introduced in 1924/1925 as the successor to the
Enigma A. Different versions of the Enigma B have existed,
including a Swedish one.
The letters on the keyboard and on the lamp panel are organised in the
order of the alphabet. It is the first Enigma with removable wheels.
Enigma C was the successor to the Enigma B. It is the first machine
has a power switch at the top, plus two terminals for connecting an
external power supply. It has an improved keyboard and contains two
spare light bulbs.
A special variant of the Enigma C — known as
Funkschlüssel C — was
used by the German Reichsmarine from 1926 onwards. It has 28
contact points and 29 keys on its keyboard.
The Enigma D was developed in 1926 as the successor to the
Enigma C. It is often referred to as the
Commercial Enigma.
The official model number was A26
and it was given the internal designator Ch. 8.
The image on the right shows a rare sample of the Commercial Enigma
that was found in 2024.
The Enigma K can be regarded as a series of 'special' machines
based on the design of the Enigma D. The official
model number is A27 and the first internal designator for this
machine is Ch. 11b. The machine was introduced in 1927, but it
wasn't before 1936 that the letter K was used in the serial number.
Other machines, such as the
Tirpitz (T),
the KD and
the Swiss K, belong to this family.
At some point in the Enigma family tree, a machine was developed
with an improved wheel-turnover mechanism and a counter. It was
called the Zählwerk Enigma and was used by
various intarnational commercial and military customers.
The later Enigma G (model G31) is also known as Zählwerk Enigma
and is based on this machine.
The Enigma I is the most well-known Enigma.
It was developed especially for the German Reichswehr
(later: Wehrmacht). All military Enigma machines are based on this model.
Is has three cipher rotors, a fixed reflector (Umkehrwalze, UKW)
and a plug board (Steckerbrett).
The initial Naval Enigma (M1, M2 and M3) is functionally identical
to this machine, but has letters on the rotors rather than numbers.
The Enigma Z is a rather strange variant of the light bulb machine
(Glühlampenmaschine) as it only has 10 keys and 10 lamps, containing
the numbers 0 thru 9.
Not much is known about this machine, although it is likely that there
were two different versions of it; one based on the Enigma D
and the other based on the Zählwerk Enigma (G).
The Enigma G (model G31) was a slighly smaller variant of
Zählwerk Enigma A28 (see above). The machine was sold to
various international customers and was also used during WWII
by the German intelligence service, the Abwehr.
Because the Abwehr was the biggest customer of
the machine, it is often referred to as the Abwehr Enigma,
but this is a misnomer. It was not the only cipher system used
by the Abwehr, and the Abwehr was not the only user of the
machine.
The most famous version of the Enigma-K
is the one that was supplied to the Swiss Army on the eve of WWII.
For this reason it is often called the Swiss Enigma K or just Swiss K.
It was modified by the Swiss Army and was supplied with an external
lamp panel and a power supply.
As the Swiss knew that the Germans were capable of breaking Swiss Enigma traffic,
they developed NEMA as a replacement.
During WWII, the Germans used a special Enigma machine for
the German Railway (Reichsbahn).
It was basically a standard Enigma K with rewired wheels
and a rewired UKW.
Enigma traffic from the German Reichsbahn was first encountered
by the codebreakers at BP in July 1940 and
later in February 1941.
The Enigma T, codenamed Tirpitz, was developed during WWII by the Germans
especially for use by the Japanese Army. It was based on the
commercial Enigma K, but had differently wired wheels and multiple
turnovers on each wheel. Furthermore, it had an Eintrittswalze (ETW)
that was wired differently than all other Enigma machines.
➤More information
On 2 February 1942, the Kriegsmarine (German Navy) unexpectedly
introduced this new version of the Enigma machine. The M4 had
4 rotors rather than the usual 3, and was initially unbreakable by
the Allied codebreakers. It is backwards compatible
Enigma I and M3
The exta 4th rotor was used exclusively by the U-boat division of the
German Navy. The rest of the Navy used it in M3-compatible
mode.
The Enigma KD was a rare variant of the Enigma K,
that was used by Mil Amt, the successor of the Abwehr.
It is based on the Enigma K but has wheels with 9 notches
each, plus a rewirable reflector (UKW-D).
➤More information
During WWII, several attempts were made to improve the security of the
Enigma. In January 1944, the Luftwaffe (Air Force)
introduced a field-rewirable reflector, called UKW-D.
It is little known that there was a separate version of UKW-D
for the Kriegsmarine (Navy).
The UKW-D shown here is such a rare naval variant.
In another attempt to improve the security of the Enigma, the Luftwaffe
introduced the Enigma Uhr in July 1944; a small wooden box that could be
connected to the machine's Steckerbrett by means of
20 cables.
On top of the Uhr is a large wooden knob that allows the operator
to select any of 40 alternative wirings, preferably one for each new message
on a given day.
Another measure to make the Enigma safer, was the so-called
Lückenfüllerwalze (gap-fill wheel)
that featured 26 user-configurable notches. This way, the
number and position of the notches of each wheel could be
changed frequently.
The Lückenfüllerwalze was planned to be used in combination
with UKW-D, but like UKW-D and the
Uhr it came too late.
In Switzerland, each Enigma machine
that was used by the Army and the Foreign Office
— commonly known as a Swiss-K — was
supplied with a mains power supply unit (PSU).
It allows the Enigma to be powered from any mains voltage, in addition
to the internal battery.
Up to four Enigma machines can be connected simultaneously to a single
PSU.
For convenience a small printer was developed for Naval Enigma machines.
They could be fitted on top of an M3 or M4, and had an external
power supply unit.
When typing, the enciphered text was printed on a 9mm paper strip.
It is likely that this printer was only used in the shore stations,
as it has to be powered from the 75-220V AC mains.
In 1918, the first Enigma-related patent was registered by
Arthur Scherbius in Germany. Since then, numerous other inventions
have been patented by Scherbius and his collegues, in Germany
as well as in many other countries.
We've collected the most important Enigma-related patents on
a single page, which are also available for download.
Of all the different Enigma models, only the military machines – used by
the German Army before and during WWII – have a Steckerbrett (plugboard) at
the front of the machine.
This plugboard is suitable for double-ended 2-pin plugs, each with a thick
and in thin pin. It was not the first design of a Steckbrett however.
In recent years, some real Enigma messages have been recovered
from the archives and from sunken U-boats and attempts have been
undertaken to break these messages again.
This section of the website deals with some real Enigma messages,
complete with the required settings of the machine, so that they
can be decoded on a simulator.
An Enigma machine uses small - rather unusual - lamps for its output.
These lamps have a common E10 fitting, but have a somewhat
flattened glass bulb. It is important to find these lamps, as ordinary
bulbs are too high and will penetrate the celluloid lamp film.
There are two variants: clear and half-opaque.
➤More information
Many Enigma machines found today, are not in very good condition
and may require some work in order to get them going again.
In the past few years, various people have made an effort to produce
good and accurate reproduction parts in order to restore Enigma
machines. Some of these parts are available through the Crypto Museum.
Based on many years of research by Frode Weierud, we've been able
to put together the most accurate family tree of Enigma machines to date.
It shows the relationship between the various models and variants,
and provides a lot of additional information.
Please note that the tree is based on ongoing research and is therefore
subject to changes in the future.
It is sometimes thought that the Enigma was broken by
Colossus, the first electronic digital computer.
This was not the case, however.
The Enigma was broken manually (using hand methods) and with help of
an electro-mechanical device, called the
Bomba (Polish),
and Bombe (British).
The latter has been rebuilt and is now on public display at
Bletchley Park (UK).
