An
Enigma machine is any of a family of related electro-mechanical
rotor machineIn cryptography, a rotor machine is an electro-mechanical device used for encrypting and decrypting secret messages. Rotor machines were the cryptographic state-of-the-art for a brief but prominent period of history; they were in widespread use in the 1930s–1950s...
s used for the
encryptionIn cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...
and decryption of secret messages. The first Enigma was invented by
GermanThe German people are an ethnic group, in the sense of sharing a common German culture, descent, and speaking the German language as a mother tongue. Within Germany, Germans are defined by citizenship , distinguished from people of German ancestry...
engineer
Arthur ScherbiusArthur Scherbius was a German electrical engineer who patented an invention for a mechanical cipher machine, later sold as the Enigma machine.Scherbius was born in Frankfurt and his father was a small businessman...
at the end of
World War IWorld War I , also known as the First World War, the Great War, and the War to End All Wars, was a global military conflict which involved most of the world's great powers, assembled in two opposing alliances: the Triple Entente and the Triple Alliance...
. This model and its variants were used commercially from the early 1920s, and adopted by military and government services of several countries—most notably by
Nazi GermanyNazi Germany and the Third Reich are the common English names for Germany between 1933 and 1945, while it was led by Adolf Hitler and the National Socialist German Worker's Party . The name Third Reich refers to the state as the successor to the Holy Roman Empire of the Middle Ages and the German...
before and during
World War IIWorld War II, or the Second World War , was a global military conflict which involved a majority of the world's nations, including all great powers, organized into two opposing military alliances: the Allies and the Axis...
. A range of Enigma models were produced, but the German military model, the Wehrmacht Enigma, is the version most commonly discussed.
The machine has become well-known because, during World War II,
BritishThe British are citizens of the United Kingdom, of the Isle of Man, one of the Channel Islands, or of one of the British overseas territories, and their descendants. In a historical context, the term refers to the ancient Britons, the indigenous inhabitants of Great Britain south of the...
codebreakers were able to
decryptCryptanalysis of the Enigma enabled the Allies in World War II to read substantial amounts of secret Morse-coded radio communications of the Axis powers enciphered using Enigma machines...
a vast number of messages which had been enciphered using the Enigma. The
intelligenceMilitary intelligence is a military service that uses intelligence gathering disciplines to collect informations that informs commanders decision making process....
gleaned from this source, codenamed
ULTRAUltra was the name used by the British for intelligence resulting from decryption of encrypted German radio communications in World War II. The term eventually became the standard designation in both Britain and the United States for all intelligence from high-level cryptanalytic sources...
by the British, was a substantial aid to the
AlliedThe Allies of World War II were the countries that opposed the Axis powers during the Second World War . The involvement of the Allies in World War II was either natural and inevitable they were invaded or under the direct threat of invasion by the Axis or compelled by concerns that the Axis powers...
war effort. The exact influence of ULTRA on the course of the war is debated; an oft-repeated assessment is that decryption of German ciphers hastened the
end of the European warVictory in Europe Day was on 8 May 1945, the date when the World War II Allies formally accepted the unconditional surrender of the armed forces of Nazi Germany and the end of Adolf Hitler's Third Reich...
by two years.
Though the Enigma cipher had cryptographic weaknesses, in practice it was only in combination with other factors (procedural flaws, operator mistakes, occasional captured hardware and key tables, etc.) that those weaknesses allowed Allied cryptographers to cryptanalyze so many messages.
Description
Like other rotor machines, the Enigma machine is a combination of mechanical and electrical subsystems. The mechanical subsystem consists of a
keyboardAlphanumeric keyboards include typewriters and computer keyboards. An alphanumeric keyboard is a device with many keys - Computer Keyboards :...
; a set of rotating disks called rotors arranged adjacently along a
spindleAn axle is a central shaft for a rotating wheel or gear. In some cases the axle may be fixed in position with a bearing or bushing sitting inside the hole in the wheel or gear to allow the wheel or gear to rotate around the axle. In other cases the wheel or gear may be fixed to the axle, with...
; and one of various stepping components to turn one or more of the rotors with each key press. The stepping component varies slightly from model to model. Most often the right-hand rotor steps once with each key stroke, and other rotors step occasionally. The continual movement of the rotors results in a different cryptographic substitution after each key press.
The mechanical parts act in such a way as to form a varying
electrical circuitAn electrical network is an interconnection of electrical elements such as resistors, inductors, capacitors, transmission lines, voltage sources, current sources, and switches....
; the actual letter substitution is indicated electrically. When a key is pressed, the circuit is completed; current flows through the various components in their current configuration and ultimately lights one of the display
lampsA lamp is a replaceable component such as an incandescent light bulb, which is designed to produce light from electricity. These components usually have a base of ceramic, metal, glass or plastic, which makes an electrical connection in the socket of a light fixture. This connection may be made...
, indicating the output letter. For example, when encrypting a message starting ANX…
, the operator would first press the A
key, and the Z
lamp might light, so Z
would be the first letter of the ciphertext. The operator would next press N
, and then X in the same fashion, and so on.
To illustrate the detailed operation of Enigma, please refer to the wiring diagram to the left. To simplify the example, only four components of a complete Enigma machine are shown. In reality, there are 26 lamps and keys, several plugs (varied with model) and rotor wirings inside the rotors (at least three were installed). Current flowed from the battery (1) through a depressed bi-directional letter-switch (2) to the plugboard (3). The plugboard allows rewiring of some letter connections between the keyboard (2) and the fixed entry wheel (4). Next, the current wends through the (unused in this instance, so shown closed) plug (3) via the entry wheel (4) through the wiring of the three (Wehrmacht Enigma) or four (Kriegsmarine
M4 and Abwehr variants) installed rotors (5), and enters the reflector (6). The reflector returns the current, via an entirely different path, through the rotors (5) and entry wheel (4), proceeding through plug 'S' connected with a cable (8) to plug 'D', and another bi-directional switch (9) to light the appropriate lamp.
The repeated changes of electrical paths through an Enigma, because of the rotation of the rotors (which cause the pin contacts to change with each letter typed), implemented a
polyalphabeticA polyalphabetic cipher is any cipher based on substitution, using multiple substitution alphabets. The Vigenère cipher is probably the best-known example of a polyalphabetic cipher, though it is a simplified special case...
encryption which provided Enigma's high security.
Rotors
The rotors (alternatively wheels
or drums
, Walzen in German) formed the heart of an Enigma machine. Each rotor was a disc approximately 10 cm in diameter made from hard
rubberNatural rubber is an elastomer that was originally derived from a milky colloidal suspension, or latex, found in the sap of some plants. The purified form of natural rubber is the chemical polyisoprene, which can also be produced synthetically...
or
bakeliteBakelite , or polyoxybenzylmethylenglycolanhydride, is an early plastic. It is a thermosetting phenol formaldehyde resin, formed from an elimination reaction of phenol with formaldehyde, usually with a wood flour filler. It was developed in 1907–1909 by Belgian chemist Dr...
with
brassBrass is any alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties. In comparison, bronze is principally an alloy of copper and tin. Despite this distinction, some types of brasses are called bronzes. Brass is a...
spring-loaded pins on one face arranged in a circle; on the other side are a corresponding number of circular electrical contacts. The pins and contacts represent the
alphabetAn alphabet is a standardized set of letters basic written symbols or graphemes each of which roughly represents a phoneme in a spoken language, either as it exists now or as it was in the past. There are other systems, such as logographies, in which each character represents a word, morpheme, or...
—typically the 26 letters A–Z (this will be assumed for the rest of this description). When the rotors were mounted side-by-side on the spindle, the pins of one rotor rest against the contacts of the neighbouring rotor, forming an electrical connection. Inside the body of the rotor, 26 wires connected each pin on one side to a contact on the other in a complex pattern. Most of the rotors were identified by Roman numerals and each issued copy of rotor I was wired identically to all others. The same was true of the special thin beta and gamma rotors used in the M4 naval variant.
By itself, a rotor will perform only a very simple type of
encryptionIn cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...
—a simple
substitution cipherIn cryptography, a substitution cipher is a method of encryption by which units of plaintext are replaced with ciphertext according to a regular system; the "units" may be single letters , pairs of letters, triplets of letters, mixtures of the above, and so forth...
. For example, the pin corresponding to the letter E
might be wired to the contact for letter T on the opposite face, and so on. The Enigma's complexity, and cryptographic security, came from using several rotors in series (usually three or four) and the regular stepping movement of the rotors, thus implementing a poly-alphabetic substitution cipher.
When placed in an Enigma, each rotor can be set to one of 26 possible positions. When inserted, it can be turned by hand using the grooved finger-wheel which protrudes from the internal Enigma cover when closed. So that the operator can know the rotor's position, each had an alphabet tyre (or letter ring) attached to the outside of the rotor disk, with 26 characters (typically letters); one of these could be seen through the window, thus indicating the rotational position of the rotor. In early Enigma models, the alphabet ring was fixed to the rotor disk. An improvement introduced in later variants was the ability to adjust the alphabet ring relative to the rotor disk. The position of the ring was known as the Ringstellung ("ring setting"), and was a part of the initial setting of an Enigma prior to an operating session. In modern terms it was a part of the
session keyA session key is a single-use symmetric key used for encrypting all messages in one communication session. A closely related term is traffic encryption key or TEK, which refers to any key used to encrypt messages as opposed to different uses, such as encrypting other keys Session keys introduce...
.
The rotors each contained a notch (more than one for some rotors) which was used to control rotor stepping. In the military variants, the notches are located on the alphabet ring.
The Army and Air Force Enigmas were used with several rotors; when first issued, there were only three. On 15 December 1938, this changed to five, from which three were chosen for insertion in the machine for a particular operating session. Rotors were marked with
Roman numeralsRoman numerals are a numeral system of ancient Rome based on letters of the alphabet, which are combined to signify the sum of their values. The first ten Roman numerals are:...
to distinguish them: I, II, III, IV and V, all with single notches located at different points on the alphabet ring. This variation was probably intended as a security measure, but ultimately allowed the Polish
Clock MethodIn cryptography, the clock was a method devised by Polish mathematician-cryptologist Jerzy Różycki, at the Polish General Staff's Cipher Bureau, to facilitate decrypting German Enigma ciphers.-Method:...
and British
BanburismusBanburismus was a cryptanalytic process developed by Alan Turing at Bletchley Park in England during the Second World War. It was used by Bletchley Park's Hut 8 to help break German Kriegsmarine messages enciphered on Enigma machines. The process used Bayesian conditional probability to infer...
attacks.
The Naval version of the
WehrmachtWehrmacht was the name of the unified armed forces of Germany from 1935 to 1945. It consisted of the Heer , the Kriegsmarine and the Luftwaffe ....
Enigma had always been issued with more rotors than the other services: at first six, then seven, and finally eight. The additional rotors were marked VI, VII and VIII, all with different wiring, and had two notches cut into them at N
and A
, resulting in a more frequent turnover.
The four-rotor Naval Enigma (M4) machine accommodated an extra rotor in the same space as the three-rotor version. This was accomplished by replacing the original reflector with a thinner one and by adding a special, also thin, fourth rotor. That fourth rotor was one of two types, Beta
or Gamma, and never stepped, but it could be manually placed in any of its 26 possible positions.
Stepping motion
To avoid merely implementing a simple (and easily breakable) substitution cipher, every key press caused one or more rotors to step and so changed the substitution alphabet used for encryption. This ensured the cryptographic substitution would be different at each new rotor position, producing a more formidable
polyalphabetic substitution cipherA polyalphabetic cipher is any cipher based on substitution, using multiple substitution alphabets. The Vigenère cipher is probably the best-known example of a polyalphabetic cipher, though it is a simplified special case...
.
The most common arrangement used a
ratchetA ratchet is a device that allows continuous linear or rotary motion in only one direction while preventing motion in the opposite direction. The term is also commonly used to refer to a socket wrench, which employs an internal ratchet mechanism....
and
pawlA ratchet is a device that allows continuous linear or rotary motion in only one direction while preventing motion in the opposite direction. The term is also commonly used to refer to a socket wrench, which employs an internal ratchet mechanism....
mechanism. Each rotor had a ratchet with 26 teeth and, every time a key was pressed, each of the pawls corresponding to a particular rotor would move forward in unison, trying to engage with a ratchet, thus stepping the attached rotor once. A thin metal ring attached to each rotor upon which the pawl rode normally prevented this. As this ring rotated with its rotor, a notch machined into it would eventually align itself with the pawl, allowing it to drop into position, engage with the ratchet, and advance the rotor. The first rotor, having no previous rotor (and therefore no notched ring controlling a pawl), stepped with every key press. The five basic rotors (I–V) had one notch each, while the additional naval rotors VI, VII and VIII had two notches. The position of the notch on each rotor could be adjusted.
If this were all the Enigma machine did, rotor one would step 26 times for every step of rotor two and rotor two 26 times for every step of rotor three. However, the design also included a feature known as double-stepping. This was enabled due to each pawl being aligned with both the ratchet of its rotor and the rotating notched ring of the neighbouring rotor. If a pawl was allowed to engage with a ratchet through alignment with a notch, as it moved forward it would push against both the ratchet and the notch, advancing both rotors at the same time. In a three-rotor machine the double-stepping would affect rotor two only. This, if in moving forward allowed the ratchet of rotor three to be engaged, would move again on the subsequent keystroke, thus resulting in two consecutive steps. Rotor two also pushes rotor one forward after 26 of its steps, but as rotor one moves forward with every keystroke anyway, there is no double-stepping. This double stepping caused the rotors to deviate from
odometerAn odometer indicates distance traveled by a car or other vehicle. The device may be electronic, mechanical, or a combination of the two. The word derives from the Greek words ""hodós", meaning "path" or "way", and "métron", "measure".-Description:In the early autos a top reading of 99,999 was...
style regular motion.
With three wheels and only single notches in the first and second wheels, the machine had a period of 26 × 25 × 26 = 16,900 (not 26 × 26 × 26 because of the double stepping of the second rotor). Historically, messages were limited to a few hundred letters, and so there was no chance of repeating any net combined rotor position during a single message session, and so cryptanalysts were denied a valuable clue to the substitution used.
To make room for the Naval fourth rotors, Beta
and Gamma (introduced in 1942), the reflector was changed, by making it much thinner. The special fourth rotors fit into the space made available. No changes were made to the rest of the mechanism, which eased the changeover to the new mode of operation. Since there were only three pawls, the fourth rotor never stepped, but could be manually set into one of its 26 possible positions.
When pressing a key, the rotors stepped before the electrical circuit was connected.
Entry wheel
The entry wheel (Eintrittswalze in German), or entry
statorThe stator is the stationary part of a rotor system, such as in an electric generator or a mechanical generator.Depending on the configuration of a spinning electromotive device the stator may act as the field magnet, interacting with the armature to create motion, or it may act as the armature,...
, connects the
plugboardA plugboard, or control panel , is an array of jacks, or hubs, into which patch cords can be inserted to complete an electrical circuit. Control panels were used to direct the operation of some unit record equipment...
, if present, or otherwise the keyboard and lampboard, to the rotor assembly. While the exact wiring used is of comparatively little importance to the security, it proved an obstacle in the progress of
PolishPoland , officially the Republic of Poland , is a country in Central Europe . Poland is bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
cryptanalyst
Marian RejewskiMarian Adam Rejewski was a Polish mathematician and cryptologist who in 1932 solved the plugboard-equipped Enigma machine, the main cipher device used by Germany...
during his deduction of the rotor wirings. The commercial Enigma connects the keys in the order of their sequence on the keyboard: Q'A
, W
'B, E'C
and so on. However, the military Enigma connects them in straight alphabetical order: A
'A, B'B
, C
'C, etc. It took an inspired piece of guesswork for Rejewski to realise the modification.
Reflector
With the exception of the early models A
and B, the last rotor came before a reflector
(German: Umkehrwalze
, meaning reversal rotor), a patented feature distinctive of the Enigma family amongst the various rotor machines designed in the period. The reflector connected outputs of the last rotor in pairs, redirecting current back through the rotors by a different route. The reflector ensured that Enigma is self-reciprocal: conveniently, encryption was the same as decryption. However, the reflector also gave Enigma the property that no letter ever encrypted to itself. This was a severe conceptual flaw and a cryptological mistake subsequently exploited by codebreakers.
In the commercial Enigma model C
, the reflector could be inserted in one of two different positions. In Model D
, the reflector could be set in 26 possible positions, although it did not move during encryption. In the Abwehr Enigma, the reflector stepped during encryption in a manner like the other wheels.
In the German Army and Air Force Enigma, the reflector was fixed and did not rotate; there were four versions. The original version was marked A
, and was replaced by Umkehrwalze B on 1 November 1937. A third version,
Umkehrwalze C was used briefly in 1940, possibly by mistake, and was solved by Hut 6Hut 6 was a wartime section of Bletchley Park tasked with the solution of German Army and Air Force Enigma machine ciphers. Hut 8, by contrast, attacked Naval Enigma...
. The fourth version, first observed on 2 January 1944, had a rewireable reflector, called Umkehrwalze D, allowing the Enigma operator to alter the connections as part of the key settings.
Plugboard
The plugboard (
Steckerbrett in German) permitted variable wiring that could be reconfigured by the operator (visible on the front panel of Figure 1; some of the patch cords can be seen in the lid). It was introduced on German Army versions in 1930, and was soon adopted by the Navy as well. The plugboard contributed a great deal to the strength of the machine's encryption: more than an extra rotor would have done. Enigma without a plugboard (known as
unsteckered Enigma) can be solved relatively straightforwardly using hand methods; these techniques are generally defeated by the addition of a plugboard, and Allied cryptanalysts resorted to special machines to solve it.
A cable placed onto the plugboard connected letters up in pairs; for example,
E and
Q might be a steckered pair. The effect was to swap those letters before and after the main rotor scrambling unit. For example, when an operator presses
E, the signal was diverted to
Q before entering the rotors. Several such steckered pairs, up to 13, might be used at one time. However, normally only 10 pairs were used at any one time.
Current flowed from the keyboard through the plugboard, and proceeded to the entry-rotor or
Eintrittswalze. Each letter on the plugboard had two jacks. Inserting a plug disconnected the upper jack (from the keyboard) and the lower jack (to the entry-rotor) of that letter. The plug at the other end of the crosswired cable was inserted into another letter's jacks, thus switching the connections of the two letters.
Accessories
A feature that was used on the M4 Enigma was the
Schreibmax, a little
printerIn computing, a printer is a peripheral which produces a hard copy of documents stored in electronic form, usually on physical print media such as paper or transparencies. Many printers are primarily used as local peripherals, and are attached by a printer cable or, in most newer printers, a USB...
which could print the 26 letters on a small paper ribbon. This did away with the need for a second operator to read the lamps and write the letters down. The
Schreibmax was placed on top of the Enigma machine and was connected to the lamp panel. To install the printer, the lamp cover and all light bulbs had to be removed. Besides its convenience, it could improve operational security; the printer could be installed remotely such that the signal officer operating the machine no longer had to see the decrypted
plaintextIn cryptography, plaintext is information a sender wishes to transmit to a receiver. Cleartext is, sometimes confusingly, often used as a synonym. Before the computer era, plaintext most commonly meant message text in the language of the communicating parties...
information.
Another accessory was the remote lamp panel. If the machine was equipped with an extra panel, the wooden case of the Enigma was wider and could store the extra panel. There was a lamp panel version that could be connected afterwards, but that required, just as with the
Schreibmax, that the lamp panel and lightbulbs be removed. The remote panel made it possible for a person to read the decrypted plaintext without the operator seeing it.
In 1944, the
Luftwaffe introduced an extra plugboard switch, called the Uhr (clock). There was a little box, containing a switch with 40 positions. It replaced the default plugs. After connecting the plugs, as determined in the daily key sheet, the operator turned the switch into one of the 40 positions, each position producing a different combination of plug wiring. Most of these plug connections were, unlike the default plugs, not pair-wise. In one switch position, the Uhr did not swap any letters, but simply emulated the 13 stecker wires with plugs.
Mathematical description
The Enigma transformation for each letter can be specified mathematically as a product of
permutationIn several fields of mathematics the term permutation is used with different but closely related meanings. They all relate to the notion of mapping the elements of a set to other elements of the same set, i.e., exchanging elements of a set.- Definitions :The general concept of permutation can be...
s. Assuming a three-rotor German Army/Air Force Enigma, let denote the plugboard transformation, denote that of the reflector, and denote those of the left, middle and right rotors respectively. Then the encryption can be expressed as
.
After each key press, the rotors turn, changing the transformation. For example, if the right hand rotor is rotated positions, the transformation becomes , where is the
cyclic permutationA cyclic permutation is built from one or more sets of elements in cyclic order.The notion cyclic permutation is used in different, but related ways:- Definition 1 :right|mapping of permutation...
mapping
A to
B,
B to
C, and so forth. Similarly, the middle and left-hand rotors can be represented as and rotations of and . The encryption transformation can then be described as
.
Operation
In German military usage, communications were divided up into a number of different networks, all using different settings for their Enigma machines. These communication nets were termed
keys at
Bletchley ParkBletchley Park, also known as Station X, is an estate located in the town of Bletchley, in Buckinghamshire, England. Since 1967, Bletchley has been part of Milton Keynes....
, and were assigned
code nameA code name or cryptonym is a word or name used clandestinely to refer to another name or word. Code names are often used for military purposes, or in espionage...
s, such as
Red,
Chaffinch, and
Shark. Each unit operating on a network was assigned a settings list for its Enigma for a period of time. For a message to be correctly encrypted and decrypted, both sender and receiver had to set up their Enigma in the same way; the rotor selection and order, the starting position and the plugboard connections must be identical. All these settings (together the
keyIn cryptography, a key is a piece of information that determines the functional output of a cryptographic algorithm or cipher. Without a key, the algorithm would have no result. In encryption, a key specifies the particular transformation of plaintext into ciphertext, or vice versa during decryption...
in modern terms) must have been established beforehand, and were distributed in
codebookIn cryptography, a codebook is a document used for implementing a code. A codebook contains a lookup table for coding and decoding; each word or phrase has one or more strings which replace it. To decipher messages written in code, corresponding copies of the codebook must be available at either end...
s.
An Enigma machine's initial state, the
cryptographic keyIn cryptography, a key is a piece of information that determines the functional output of a cryptographic algorithm or cipher. Without a key, the algorithm would have no result. In encryption, a key specifies the particular transformation of plaintext into ciphertext, or vice versa during decryption...
, has several aspects:
- Wheel order (Walzenlage)—the choice of rotors and the order in which they are fitted.
- Initial position of the rotors—chosen by the operator, different for each message.
- Ring settings (Ringstellung)—the position of the alphabet ring relative to the rotor wiring.
- Plug settings (Steckerverbindungen)—the connections of the plugs in the plugboard.
- In very late versions, the wiring of the reconfigurable reflector.
Note that although the ring settings (
ringstellung) were a required part of the setup, they did not actually effect the message encryption because the rotors were positioned independently of the rings. The ring settings were only necessary to determine the initial rotor position based on the
message setting which was transmitted at the beginning of a message, as described in the "Indicators" section, below. Once the receiver had set to his rotors to the indicated positions, the ring settings no longer played any role in the encryption.
In modern cryptographic language, the ring settings did not actually contribute
entropyIn information theory, entropy is a measure of the uncertainty associated with a random variable. The term by itself in this context usually refers to the Shannon entropy, which quantifies, in the sense of an expected value, the information contained in a message, usually in units such as bits...
to the key used for encrypting the message. Rather, the ring settings were part of a separate key (along with the rest of the setup such as wheel order and plug settings) used to encrypt a
session key for the message. The session key consisted of the complete setup
except for the ring settings, plus the initial rotor positions chosen arbitrarily by the sender (the
message setting). The important part of this session key was the rotor positions, not the ring positions. However, by
encoding the rotor position into the ring position using the ring settings, additional variability was added to the encryption of the session key.
Enigma was designed to be secure even if the rotor wiring was known to an opponent, although in practice there was considerable effort to keep the wiring secret. If the wiring is secret, the total number of possible configurations has been calculated to be around 10
114 (approximately 380 bits); with known wiring and other operational constraints, this is reduced to around 10
23 (76 bits). Users of Enigma were confident of its security because of the large number of possibilities; it was not then feasible for an adversary to even begin to try every possible configuration in a
brute force attackIn cryptography, a brute force attack is a strategy used to break the encryption of data. It involves traversing the search space of possible keys until the correct key is found....
.
Indicators
Most of the keys were kept constant for a set time period, typically a day. However, a different initial rotor position was chosen for each message, a concept similar to an
initialisation vectorIn cryptography, an initialization vector is a block of bits that is required to allow a stream cipher or a block cipher to be executed in any of several streaming modes of operation to produce a unique stream independent from other streams produced by the same encryption key, without having to go...
in modern cryptography, because if a number of messages are sent encrypted with identical or near-identical settings a cryptanalyst, with several messages "in depth", might be able to attack the messages using frequency analysis. The starting position was transmitted just before the ciphertext. The exact method used was termed the "indicator procedure"—weak indicator procedures allowed the initial breaks into Enigma.
One of the earliest indicator procedures was used by Polish cryptanalysts to make the initial breaks into the Enigma. The procedure was for the operator to set up his machine in accordance with his settings list, which included a global initial position for the rotors (
Grundstellung, meaning
ground setting),
AOH, perhaps. The operator turned his rotors until
AOH was visible through the rotor windows. At that point, the operator chose his own, arbitrary, starting position for that particular message. An operator might select
EIN, and these became the
message settings for that encryption session. The operator then typed
EIN into the machine, twice, to allow for detection of transmission errors. The results were an encrypted indicator—the
EIN typed twice might turn into
XHTLOA, which would be transmitted along with the message. Finally, the operator then spun the rotors to his message settings,
EIN in this example, and typed the plaintext of the message.
At the receiving end, the operation was reversed. The operator set the machine to the initial settings and typed in the first six letters of the message (
XHTLOA). In this example,
EINEIN emerged on the lamps. After moving his rotors to
EIN, the receiving operator then typed in the rest of the ciphertext, deciphering the message.
The weakness in this indicator scheme came from two factors. First, use of a global ground setting—this was later changed so the operator selected his initial position to encrypt the indicator, and sent the initial position in the clear. The second problem was the repetition of the indicator, which was a serious security flaw. The message setting was encoded twice, resulting in a relation between first and fourth, second and fifth, and third and sixth character. This security problem enabled the Polish Cipher Bureau to break into the pre-war Enigma system as early as 1932. However, from 1940 on, the Germans changed the procedures to increase the security.
During World War II, codebooks were only used each day to set up the rotors, their ring settings and the plugboard. For each message, the operator selected a random start position, let's say
WZA, and a random message key, perhaps
SXT. He moved the rotors to the
WZA start position and encoded the message key
SXT. Assume the result was
UHL. He then set up the message key,
SXT, as the start position and encrypted the message. Next, he transmitted the start position,
WZA, the encoded message key,
UHL, and then the ciphertext. The receiver set up the start position according to the first trigram,
WZA, and decoded the second trigram,
UHL, to obtain the
SXT message setting. Next, he used this
SXT message setting as the start position to decrypt the message. This way, each ground setting was different and the new procedure avoided the security flaw of double encoded message settings.
This procedure was used by Wehrmacht and Luftwaffe only. The Kriegsmarine procedures on sending messages with the Enigma were far more complex and elaborate. Prior to encryption with the Enigma, the message was encoded using the Kurzsignalheft code book. The Kurzsignalheft contained tables to convert sentences into four-letter groups. A great many choices were included, e.g. logistic matters such as refueling and rendezvous with supply ships, positions and grid lists, harbor names, countries, weapons, weather conditions, enemy positions and ships, date and time tables. Another codebook contained the
Kenngruppen and
Spruchschlüssel: the key identification and message key.
Abbreviations and guidelines
The Army Enigma machine used only the 26 alphabet characters. Signs were replaced by rare character combinations. A space was omitted or replaced by an X. The X was generally used as point or full stop. Some signs were different in other parts of the armed forces. The Wehrmacht replaced a comma by ZZ and the question sign by FRAGE or FRAQ. The
Kriegsmarine, however, replaced the comma by Y and the question sign by UD. The combination CH, as in "Acht" (eight) or "Richtung" (direction) were replaced by Q (AQT, RIQTUNG). Two, three and four zeros were replaced by CENTA, MILLE and MYRIA.
The
Wehrmacht and the
Luftwaffe transmitted messages in groups of five characters. The
Kriegsmarine, using the four rotor Enigma, had four-character groups. Frequently used names or words were to be varied as much as possible. Words like
Minensuchboot (minesweeper) could be written as MINENSUCHBOOT, MINBOOT, MMMBOOT or MMM354. To make cryptanalysis harder, more than 250 characters in one message were forbidden. Longer messages were divided into several parts, each using its own message key. For more details see Tony Sale's translations of "General Procedure" and "Officer and Staff procedure".
History and development of the machine
Far from being a single design, there are numerous models and variants of the Enigma family. The earliest Enigma machines were commercial models dating from the early 1920s. Starting in the mid-1920s, the various branches of the German military began to use Enigma, making a number of changes in order to increase its security. In addition, a number of other nations either adopted or adapted the Enigma design for their own cipher machines.
Commercial Enigma
On 23 February 1918 German engineer
Arthur ScherbiusArthur Scherbius was a German electrical engineer who patented an invention for a mechanical cipher machine, later sold as the Enigma machine.Scherbius was born in Frankfurt and his father was a small businessman...
applied for a patent for a cipher machine using rotors and, with E. Richard Ritter, founded the firm of Scherbius & Ritter. They approached the German Navy and Foreign Office with their design, but neither was interested. They then assigned the patent rights to Gewerkschaft Securitas, who founded the
Chiffriermaschinen Aktien-Gesellschaft (Cipher Machines Stock Corporation) on 9 July 1923; Scherbius and Ritter were on the board of directors.
Chiffriermaschinen AG began advertising a rotor machine—
Enigma model A—which was exhibited at the Congress of the
International Postal UnionThe Universal Postal Union is an international organization that coordinates postal policies among member nations, and hence the worldwide postal system. Each member country agrees to the same set of terms for conducting international postal duties...
in 1923 and 1924. The machine was heavy and bulky, incorporating a
typewriterA typewriter is a mechanical or electromechanical device with a set of "keys" that, when pressed, cause characters to be printed on a medium, usually paper...
. It measured 65×45×35 cm and weighed about 50 kg. A
model B was introduced, and was of a similar construction. While bearing the Enigma name, both models
A and
B were quite unlike later versions: they differed in physical size and shape, but also cryptographically, in that they lacked the reflector.
The reflector—an idea suggested by Scherbius's colleague Willi Korn—was first introduced in the
Enigma C (1926) model. The reflector is a key feature of the Enigma machines.
Model C was smaller and more portable than its predecessors. It lacked a typewriter, relying instead on the operator reading the lamps; hence the alternative name of "glowlamp Enigma" to distinguish from models
A and
B. The
Enigma C quickly became extinct, giving way to the
Enigma D (1927). This version was widely used, with examples going to
SwedenSweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe...
, the
NetherlandsThe Netherlands is a country in Northwestern Europe, constituting the major portion of the Kingdom of the Netherlands. It is a parliamentary democratic constitutional monarchy. The Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east...
,
United KingdomThe United Kingdom of Great Britain and Northern Ireland is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of Ireland, and many small islands...
,
Japanis an island country in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, People's Republic of China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
,
ItalyItaly , officially the Italian Republic , is a country located on the Italian Peninsula in Southern Europe and on the two largest islands in the Mediterranean Sea, Sicily and Sardinia. Italy shares its northern, Alpine boundary with France, Switzerland, Austria and Slovenia...
,
SpainSpain , officially the Kingdom of Spain , is a country located in southwestern Europe on the Iberian Peninsula.
[The Spanish constitution does not establish any official denomination of the country, even though España , Estado español and Nación española are used interchangeably...]
,
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
, and
PolandPoland , officially the Republic of Poland , is a country in Central Europe . Poland is bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
.
Military Enigma
The Navy was the first branch of the German military to adopt Enigma. This version, named Funkschlüssel
C ("Radio cipher C"), had been put into production by 1925 and was introduced into service in 1926. The keyboard and lampboard contained 29 letters—A-Z, Ä, Ö and Ü—which were arranged alphabetically, as opposed to the QWERTZU ordering. The rotors had 28 contacts, with the letter X
wired to bypass the rotors unencrypted. Three rotors were chosen from a set of five and the reflector could be inserted in one of four different positions, denoted α, β, γ and δ. The machine was revised slightly in July 1933.
By 15 July 1928, the German Army (ReichswehrThe Reichswehr formed the military organisation of Germany from 1919 until 1935, when it was renamed the Wehrmacht ....
) had introduced their own version of the Enigma—the Enigma G, revised to the Enigma I by June 1930. Enigma I is also known as the Wehrmacht, or "Services" Enigma, and was used extensively by the German military services and other government organisations (such as the
railwaysThe Deutsche Reichsbahn – was the name of the German national railway created from the railways of the individual states of the German Empire following the end of World War I....
), both before and during
World War IIWorld War II, or the Second World War , was a global military conflict which involved a majority of the world's nations, including all great powers, organized into two opposing military alliances: the Allies and the Axis...
. The major difference between Enigma I and commercial Enigma models was the addition of a plugboard to swap pairs of letters, greatly increasing the cryptographic strength of the machine. Other differences included the use of a fixed reflector, and the relocation of the stepping notches from the rotor body to the movable letter rings. The machine measured 28×34×15 cm (11"×13.5"×6") and weighed around 12 kg (26 lbs).
By 1930, the Army had suggested that the Navy adopt their machine, citing the benefits of increased security (with the plugboard) and easier interservice communications. The Navy eventually agreed and in 1934 brought into service the Navy version of the Army Enigma, designated Funkschlüssel M or
M3. While the Army used only three rotors at that time, for greater security the Navy specified a choice of three from a possible five.
In December 1938, the Army issued two extra rotors so that the three rotors were chosen from a set of five. In 1938, the Navy added two more rotors, and then another in 1939 to allow a choice of three rotors from a set of eight. In August 1935, the Air Force also introduced the Wehrmacht Enigma for their communications. A four-rotor Enigma was introduced by the Navy for U-boat traffic on 1 February 1942, called
M4 (the network was known as "Triton", or "Shark" to the Allies). The extra rotor was fitted in the same space by splitting the reflector into a combination of a thin reflector and a thin fourth rotor.
There was also a large, eight-rotor printing model, the
Enigma II. In 1933 the Polish Cipher Bureau detected that it was in use for high-level military communications, but that it was soon withdrawn from use after it was found to be unreliable and to jam frequently.
The
AbwehrThe Abwehr was a German military intelligence organisation from 1921 to 1944. The term Abwehr was used as a concession to Allied demands that Germany's post-World War I intelligence activities be for "defensive" purposes only...
used the
Enigma G (the
Abwehr Enigma). This Enigma variant was a four-wheel unsteckered machine with multiple notches on the rotors. This model was equipped with a counter which incremented upon each key press, and so is also known as the "counter machine" or the Zählwerk Enigma.
Other countries also used Enigma machines. The Italian Navy adopted the commercial Enigma as "Navy Cipher D"; the Spanish also used commercial Enigma during their
Civil WarThe Spanish Civil War was a major conflict that devastated Spain from 17 July 1936 to 1 April 1939. It began after an attempted coup d'état by a group of Spanish Army generals against the government of the Second Spanish Republic, then under the leadership of president Manuel Azaña...
. British codebreakers succeeded in breaking these machines, which lacked a plugboard. The Swiss used a version of Enigma called
model K or
Swiss K for military and diplomatic use, which was very similar to the commercial Enigma D. The machine was broken by a number of parties, including Poland, France, Britain and the United States (the latter codenamed it INDIGO). An
Enigma T model (codenamed
Tirpitz) was manufactured for use by the Japanese.
It has been estimated that 100,000 Enigma machines were constructed. After the end of the Second World War, the Allies sold captured Enigma machines, still widely considered secure, to a number of developing countries.
Surviving Enigma machines
The effort to break the Enigma was not disclosed until the 1970s. Since then, interest in the Enigma machine has grown considerably and a number of Enigmas are on public display in
museumA museum is a building or institution which houses a collection of artifacts.Museums collect and care for objects of scientific, artistic, or historical importance and make them available for public viewing through exhibits that may be permanent or temporary...
s in the U.S. and Europe. The
Deutsches MuseumThe Deutsches Museum in Munich, Germany, is the world's largest museum of technology and science, with approximately 1.5 million visitors per year and about 28,000 exhibited objects from 50 fields of science and technology. The museum was founded on June 28, 1903, at a meeting of the Association...
in
MunichMunich is the capital city of Bavaria, Germany. It is located on the River Isar north of the Bavarian Alps. Munich is the third largest city in Germany, after Berlin and Hamburg...
has both the three- and four-rotor German military variants, as well as several older civilian versions. A functional Enigma is on display in the
NSAThe National Security Agency/Central Security Service is a cryptologic intelligence agency of the United States government, administered as part of the United States Department of Defense. Created on November 4, 1952 by President Harry S...
's
National Cryptologic MuseumThe United States National Cryptologic Museum is a museum of cryptologic history, affiliated with the National Security Agency . Located in a former motel two blocks from the NSA headquarters at Fort George G. Meade, Maryland, the museum collection contains thousands of artifacts, including a...
at
Fort MeadeFort George G. Meade, located adjacent to Odenton, Maryland, in Anne Arundel County, is an active U.S. Army installation. The fort, established in 1917, is named for General George Meade, a Union Army general in the American Civil War...
, Maryland, where visitors can try their hand at encrypting messages and deciphering code. The Armémuseum in
Stockholm' is the capital and largest city of Sweden. It is the site of the national Swedish government, the Riksdag , and the official residence of the Swedish Monarch as well as the prime minister. The Monarch resides at Drottningholm Palace outside of Stockholm since 1980 and uses the Royal Palace of...
in Sweden had an Enigma on display. There are also examples at the
Computer History MuseumThe Computer History Museum is a museum established in 1996 in Mountain View, California, USA, when The Computer Museum sent the majority of its historical collection to Moffett Field, California, so that TCM could concentrate on computing-related exhibits for children...
in the United States, at
Bletchley ParkBletchley Park, also known as Station X, is an estate located in the town of Bletchley, in Buckinghamshire, England. Since 1967, Bletchley has been part of Milton Keynes....
in the United Kingdom, at the
Polish Army MuseumMuseum of the Polish Army is a museum in Warsaw documenting the military aspects of the history of Poland. Created in 1920, it occupies a wing of the building of the Polish National Museum as well as several branches in Poland. It's Warsaw's second largest museum and the largest collection of...
in Poland, at the
Australian War MemorialThe Australian War Memorial is Australia's national memorial to the members of all its armed forces and supporting organisations who have died or participated in the wars of the Commonwealth of Australia...
, and in the foyer of the
Defence Signals DirectorateDefence Signals Directorate is an Australian government intelligence agency responsible for signals intelligence and information security .-Overview:According to its , DSD has two principal functions:...
, both in
CanberraCanberra is the capital city of Australia. With a population of over 345,000, it is Australia's largest inland city and the eighth largest Australian city overall. The city is located at the northern end of the Australian Capital Territory, south-west of Sydney, and north-east of Melbourne...
, Australia, as well as a number of other locations in Germany, the U.S., the UK and elsewhere. The now-defunct San Diego Computer Museum had an Enigma in its collection, which has since been given to the
San Diego State UniversityFor a railway station that serves the campus, see SDSU Transit Center.San Diego State University , founded in 1897 as San Diego Normal School, is the largest and oldest higher education facility in the greater San Diego area , and is part of the California State University system...
Library. A number are also in private hands. Occasionally, Enigma machines are sold at auction; prices of US$20,000 are not unusual.
Replicas of the machine are available in various forms, including an exact reconstructed copy of the Naval M4 model, an Enigma implemented in electronics (Enigma-E), various computer software simulators and paper-and-scissors analogues.
A rare Abwehr Enigma machine, designated G312, was stolen from the Bletchley Park museum on 1 April 2000. In September, a man identifying himself as "The Master" sent a note demanding £25,000 and threatened to destroy the machine if the ransom was not paid. In early October 2000, Bletchley Park officials announced that they would pay the ransom but the stated deadline passed with no word from the blackmailer. Shortly afterwards the machine was sent anonymously to BBC journalist
Jeremy PaxmanJeremy Dickson Paxman is a British journalist, author and television presenter. He has worked for the BBC since 1977. He is noted for a forthright and abrasive interviewing style...
, but three rotors were missing. In November 2000, an antiques dealer named Dennis Yates was arrested after telephoning
The Sunday TimesThe Sunday Times is a British Sunday newspaper.The Sunday Times may also refer to:*The Sunday Times *The Sunday Times *The Sunday Times *The Sunday Times...
to arrange the return of the missing parts. The Enigma machine was returned to Bletchley Park after the incident. In October 2001, Yates was sentenced to ten months in prison after admitting handling the stolen machine and demanding ransom for its return, although he maintained that he was acting as an intermediary for a third party. Yates was released from prison after serving three months.
In October 2008 the Spanish daily newspaper
El PaísEl País is the most widely-circulated daily newspaper in Spain. According to the 2005 Estudio General de Medios , it has about 2.1 million readers; El Mundo is second with an estimated 1.29 million readers...
reported that 28 Enigma machines were discovered by chance in an attic of the Army headquarters in Madrid during inventory taking. These machines helped Franco's Nationalists win the
Spanish Civil WarThe Spanish Civil War was a major conflict that devastated Spain from 17 July 1936 to 1 April 1939. It began after an attempted coup d'état by a group of Spanish Army generals against the government of the Second Spanish Republic, then under the leadership of president Manuel Azaña...
because although the British code breaker Alfred Dilwyn Knox broke the code generated by Franco's Enigma machines in 1937, this information was not passed to the Republicans and they never managed to decipher any of the messages generated by these machines. The Nationalist government continued to use Enigma machines into the 1950s and eventually purchased 50 of them. Some of the original 28 machines are now on display in the Spanish military museums.
Enigma derivatives
The Enigma was influential in the field of cipher machine design, and a number of other rotor machines are derived from it. The British
TypexIn the history of cryptography, Typex machines were British cipher machines used from 1937. It was an adaptation of the commercial German Enigma with a number of enhancements that greatly increased its security....
was originally derived from the Enigma patents; Typex even includes features from the patent descriptions that were omitted from the actual Enigma machine. Owing to the need for secrecy about its cipher systems, no royalties were paid for the use of the patents by the British government. A Japanese Enigma clone was codenamed GREEN by American cryptographers. Little used, it contained four rotors mounted vertically. In the U.S., cryptologist
William FriedmanWilliam Frederick Friedman was a US Army cryptographer . He ran the research division of the Army's Signals Intelligence Service in the 1930s, and parts of its follow-on services into the 1950s...
designed the
M-325In the history of cryptography, M-325, also known as SIGFOY, was an American rotor machine designed by William F. Friedman in 1936. Between 1944 and 1946, more than 1,100 machines were deployed within the United States Foreign Service. Its use was discontinued in 1946 because of faults in operation...
, a machine similar to Enigma in logical operation, although not in construction.
A unique rotor machine was constructed in 2002 by
NetherlandsThe Netherlands is a country in Northwestern Europe, constituting the major portion of the Kingdom of the Netherlands. It is a parliamentary democratic constitutional monarchy. The Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east...
-based Tatjana van Vark. This unusual device was inspired by Enigma but makes use of 40-point rotors, allowing letters, numbers and some punctuation to be used; each rotor contains 509 parts.
Fiction
The play
Breaking the CodeBreaking the Code is a 1986 play by Hugh Whitemore about Alan Turing.The play thematically links Turing's cryptography activity with his attempts to grapple with his homosexuality....
, by
Hugh WhitemoreHugh Whitemore is an English playwright and screenwriter.Whitemore studied for the stage at London's Royal Academy of Dramatic Art, where he is now a Member of the Council. He began his writing career in British television with both original teleplays and adaptations of classic works by Charles...
, is about the life and death of
Alan TuringAlan Mathison Turing, OBE, FRS , was an English mathematician, logician, cryptanalyst, and computer scientist. He was influential in the development of computer science and provided an influential formalisation of the concept of the algorithm and computation with the Turing machine...
, who was the central force in continuing to break the Enigma in
BritainThe United Kingdom of Great Britain and Northern Ireland is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of Ireland, and many small islands...
during
World War IIWorld War II, or the Second World War , was a global military conflict which involved a majority of the world's nations, including all great powers, organized into two opposing military alliances: the Allies and the Axis...
. Turing was played by
Derek JacobiSir Derek George Jacobi CBE is an English actor and film director. Like Laurence Olivier, he bears the distinction of holding two knighthoods, Danish and British.-Early life:...
, who also played Turing in a 1996 television adaptation of the play. The television adaptation is generally available (though currently only on VHS). Although it is a drama and thus takes artistic license, it is nonetheless a fundamentally accurate account. It contains a two-minute, stutteringly-nervous speech by Jacobi that comes very close to encapsulating the entire British Enigma-decryption effort.
Robert HarrisRobert Dennis Harris is an English novelist. He is a former journalist and BBC TV reporter.-Early life:Harris spent his childhood in a small rented house on a Nottingham council estate. His ambition to become a writer arose at an early age, from visits to the local printing plant where his father...
' 1995 novel
Enigma is set against the backdrop of World War II
Bletchley ParkBletchley Park, also known as Station X, is an estate located in the town of Bletchley, in Buckinghamshire, England. Since 1967, Bletchley has been part of Milton Keynes....
and cryptologists working to read Naval Enigma in
Hut 8Hut 8 was a section at Bletchley Park tasked with solving German naval Enigma messages. The section was led initially by Alan Turing...
. The book, with substantial changes in plot, was made into the 2001 film
EnigmaEnigma is a 2001 British film about the Enigma codebreakers of Bletchley Park in World War II. The film, directed by Michael Apted, stars Dougray Scott and Kate Winslet...
, directed by
Michael AptedMichael David Apted, CMG is an English director, producer, writer and actor. He is one of the most prolific British film directors of his generation but is best known for his work on the Up series of documentaries....
and starring
Kate WinsletKate Elizabeth Winslet is an English actress and occasional singer. Winslet made her film debut starring in Peter Jackson's Heavenly Creatures...
and
Dougray ScottStephen Dougray Scott is a Scottish actor.-Early life:The son of Elma, a nurse, and Alan Scott, an actor and salesperson, Scott attended Auchmuty High School...
. The film has been criticized for many historical inaccuracies, including neglect of the role of
PolandPoland , officially the Republic of Poland , is a country in Central Europe . Poland is bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
's
Biuro SzyfrówThe Biuro Szyfrów was the interwar Polish General Staff's agency charged with both cryptography and cryptology .The agency that would become the "Cipher Bureau" was created in May 1919 during the Polish-Soviet War...
in breaking the Enigma cipher and showing the British how to do it. The film – like the book – makes a Pole the villain, who seeks to betray the secret of Enigma decryption.
An earlier Polish film dealing with Polish aspects of the subject was the superficial 1979
Sekret Enigmy (The Enigma Secret).
Wolfgang PetersenWolfgang Petersen is a German film director. He is known for his body of film work, which includes The NeverEnding Story, Outbreak, In the Line of Fire, Air Force One, The Perfect Storm, Troy, and Poseidon...
's 1981 film
Das BootDas Boot is a 1981 feature film directed by Wolfgang Petersen, adapted from a novel of the same name by Lothar-Günther Buchheim. Hans-Joachim Krug, former first officer on U-219, served as a consultant, as did Heinrich Lehmann-Willenbrock, the captain of the real U-96.The film is the story of a...
includes an Enigma machine which is evidently a four-rotor Kriegsmarine variant. It appears in many scenes, which probably capture well the flavour of day-to-day Enigma use aboard a
World War IIWorld War II, or the Second World War , was a global military conflict which involved a majority of the world's nations, including all great powers, organized into two opposing military alliances: the Allies and the Axis...
U-Boat. The plot of
U-571U-571 is a film directed by Jonathan Mostow, and starring Matthew McConaughey, Bill Paxton, Harvey Keitel, Thomas Kretschmann, Jon Bon Jovi, Jack Noseworthy, Will Estes, and Tom Guiry...
, released in 2000, revolves around an attempt to seize an Enigma machine from a German U-boat.
Neal StephensonNeal Town Stephenson is an American writer, known for his speculative fiction works, which have been variously categorized science fiction, historical fiction, cyberpunk, and postcyberpunk. He has also written under the pseudonym of Stephen Bury.Stephenson explores areas such as mathematics,...
's novel
CryptonomiconCryptonomicon is a 1999 novel by American author Neal Stephenson. It concurrently follows both the exploits of World War II-era Allied codebreakers and tactical-deception operatives affiliated with the Government Code and Cypher School at Bletchley Park as well as their present day descendants'...
prominently features the Enigma machine and efforts by British and American cryptologists to break variants of it, and portrays the German
U-boatU-boat is the anglicized version of the German word , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...
command under
Karl DönitzKarl Dönitz was a German naval Commander who served in the Imperial German Navy during World War I, and during World War II commanded first the German submarine fleet, and then the entire German Navy .In the final days of the war, Dönitz was named by Adolf Hitler as his successor, and after the...
using it in apparently deliberate ignorance of its having been broken.
In the comedy war film
All the Queen's MenAll the Queen's Men is a 2001 comedy war film. It was directed by Stefan Ruzowitzky and stars Matt LeBlanc and Eddie Izzard. The budget was $15,000,000, but the film only earned $22,723 worldwide, giving it a .08% return.-Cast:*O'Rourke - Matt LeBlanc...
(2001, starring
Matt LeBlancMatthew Steven "Matt" LeBlanc is an American actor, known for his role as Joey Tribbiani in the NBC sitcoms Friends and Joey.-Early life:...
and
Eddie IzzardEdward John "Eddie" Izzard is a two-time Emmy winning British stand-up comedian and actor. His comedy style is expressed in rambling, whimsical monologue and self-referential pantomime. Izzard's works include standup sets Definite Article, Dress to Kill and a starring role in the television...
), four World War II Allied soldiers are parachuted into Germany, where, dressed as women, they attempt to steal an Enigma machine. They eventually learn that the Allies already had the machine and that the mission was a
ruseA ruse is an action or plan which is intended to deceive someone. It may also refer to:*Michael Ruse, a philosopher of science*Ruse , published by CrossGen*Ruse , a RTS video game developed by Eugen Systems....
intended to mislead the Germans into thinking that Enigma was a closed book to the Allies.
See also
- Cryptanalysis of the Enigma
Cryptanalysis of the Enigma enabled the Allies in World War II to read substantial amounts of secret Morse-coded radio communications of the Axis powers enciphered using Enigma machines...
- Geheimschreiber
Fish was the Allied codename for any of several German teleprinter stream ciphers used during World War II. Enciphered teleprinter traffic was used between German High Command and Army Group commanders in the field, so its intelligence value was of the highest strategic value to the Allies...
- Lorenz cipher
The Lorenz SZ 40 and SZ 42 were German cipher machines used during World War II for teleprinter circuits. British codebreakers, who referred to encrypted German teleprinter traffic as "Fish", termed the machine and its traffic "Tunny"...
- Siemens and Halske T52
The Siemens and Halske T52, also known as the Geheimfernschreiber , or Schlüsselfernschreibmaschine , was a World War II German teleprinter cipher machine...
- SIGABA
In the history of cryptography, the ECM Mark II was a rotor machine used by the United States from World War II until the 1950s. The machine was also known as the SIGABA or Converter M-134 by the Army, or CSP-888/889 by the Navy, and a modified Navy version was termed the CSP-2900.Like many...
- Typex
In the history of cryptography, Typex machines were British cipher machines used from 1937. It was an adaptation of the commercial German Enigma with a number of enhancements that greatly increased its security....
Further reading
- Calvocoressi, Peter
Peter Calvocoressi is a British political author and a former intelligence officer at Bletchley Park during World War II.-Early years:...
. Top Secret Ultra. Baldwin, new edn 2001. 978-0-947712-36-5
- Cave Brown, Anthony
Anthony Cave Brown was an English-American journalist, espionage non-fiction writer, and historian.-Early years:...
. Bodyguard of Lies, 1975. A journalist's sensationalist best-seller that purported to give a history of Enigma decryption and its effect on the outcome of World War II. Worse than worthless on the seminal Polish work that made "UltraUltra was the name used by the British for intelligence resulting from decryption of encrypted German radio communications in World War II. The term eventually became the standard designation in both Britain and the United States for all intelligence from high-level cryptanalytic sources...
" possible. See Richard WoytakRichard Andrew Woytak was an American historian who specialized in European history of the Interbellum and World War II...
, prefatory note (pp. 75–76) to Marian RejewskiMarian Adam Rejewski was a Polish mathematician and cryptologist who in 1932 solved the plugboard-equipped Enigma machine, the main cipher device used by Germany...
, "Remarks on Appendix 1 to British Intelligence in the Second World War by F.H. HinsleySir Francis Harry Hinsley OBE was an English historian and cryptanalyst. He worked at Bletchley Park during the Second World War and wrote widely on the history of international relations and British Intelligence during the Second World War...
," CryptologiaCryptologia is a journal in cryptography published quarterly since January 1977. Its remit is all aspects of cryptography, but there is a special emphasis on historical aspects of the subject. The founding editors were Brian J. Winkel, David Kahn, Louis Kruh, Cipher A. Deavours and Greg Mellen.The...
, vol. 6, no. 1 (January 1982), pp. 76–83.
- Garliński, Józef
Józef Garliński was a Polish historian and prose writer. He wrote many notable books on the history of World War II, some of which were translated into English...
Intercept, Dent, 1979. A superficial, sometimes misleading account of Enigma decryption before and during World War II, of equally slight value as to both the Polish and British phases. See Richard WoytakRichard Andrew Woytak was an American historian who specialized in European history of the Interbellum and World War II...
and Christopher KasparekChristopher Kasparek is a Scottish-born writer of Polish descent who has edited and translated, into English, works by Ignacy Krasicki, Bolesław Prus, Florian Znaniecki, Władysław Tatarkiewicz, Marian Rejewski and Władysław Kozaczuk, as well as the Polish-Lithuanian Constitution of May 3, 1791. ...
, "The Top Secret of World War II," The Polish ReviewThe Polish Review is an English-language scholarly journal published quarterly in New York City by the Polish Institute of Arts and Sciences of America.The Polish Review has been appearing since 1956.-Editors in Chief:*Stanisław Skrzypek...
, vol. XXVIII, no. 2, 1983, pp. 98–103 (specifically, about Garliński, pp. 101–3).
- Herivel, John
John W. Herivel is a British science historian and former World War II codebreaker at Bletchley Park.As a codebreaker, Herivel is remembered chiefly for the discovery of what was soon dubbed the Herivel tip or Herivelismus...
. Herivelismus and the German military Enigma. Baldwin, 2008. 978-0-947712-46-4
- Keen, John. Harold 'Doc' Keen and the Bletchley Park Bombe. Baldwin, 2003. 978-0-947712-42-6
- Large, Christine. Hijacking Enigma, 2003, ISBN 0-470-86347-1.
- Marks, Philip. "Umkehrwalze D: Enigma's Rewirable Reflector — Part I", Cryptologia 25(2), April 2001, pp. 101–141.
- Marks, Philip. "Umkehrwalze D: Enigma's Rewirable Reflector — Part II", Cryptologia 25(3), July 2001, pp. 177–212.
- Marks, Philip. "Umkehrwalze D: Enigma's Rewirable Reflector — Part III", Cryptologia 25(4), October 2001, pp. 296–310.
- Perera, Tom. The Story of the ENIGMA: History, Technology and Deciphering, 2nd Edition, CD-ROM, 2004, Artifax Books, ISBN 1-890024-06-6 sample pages
- Rejewski, Marian
Marian Adam Rejewski was a Polish mathematician and cryptologist who in 1932 solved the plugboard-equipped Enigma machine, the main cipher device used by Germany...
. "How Polish Mathematicians Deciphered the Enigma," Annals of the History of Computing 3, 1981. This article is regarded by Andrew Hodges, Alan Turing's biographer, as "the definitive account" (see Hodges' Alan Turing: The Enigma, Walker and Company, 2000 paperback edition, p. 548, footnote 4.5).
- Quirantes, Arturo. "Model Z: A Numbers-Only Enigma Version", Cryptologia 28(2), April 2004.
- Ulbricht, Heinz. Enigma Uhr, Cryptologia, 23(3), April 1999, pp. 194–205.
- Welchman, Gordon
Gordon Welchman was a British mathematician and World War II codebreaker at Bletchley Park.-Education and early career:Gordon Welchman studied Mathematics as a scholar at Trinity College, Cambridge from 1925 to 1928...
. The Hut Six Story: breaking the Enigma codes. Baldwin, new edition, 1997. 978-0-947712-34-1
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