The Enigma cipher machine
The Enigma machine was a cipher machine used to encrypt and decrypt secret messages. This article contains technical details about the rotors of the Enigma machine. The Enigma machines were a family of portable Cipher machines The Biuro Szyfrów ( Polish for " Cipher Bureau " was the Polish Interwar agency charged with both Cryptography (the The method of perforated sheets was a cryptologic technique used by the Polish Cipher Bureau before World War II, and during the war by The Bomba, or Bomba kryptologiczna ( Polish for " Bomb " or " Cryptologic bomb " was a special-purpose Enigma "doubles" were machines produced by the Polish Cipher Bureau, based on Marian Rejewski 's reconstruction of The cyclometer was a cryptologic device designed in the end of 1936 by Marian Rejewski, of the Polish Cipher Bureau 's German section (BS-4 to facilitate Bletchley Park, also known as Station X, is an estate located in the town of Bletchley, in Buckinghamshire, and (since 1967 part of Milton Keynes Banburismus was a process invented by Alan Turing at Bletchley Park in England during the Second World War. John W Herivel (born 1918 is a British Science historian and former World War II Codebreaker at Bletchley Park. In the History of cryptography, the Bombe was an electromechanical device used by British Cryptologists to help break German Enigma Hut 6 was a wartime section of Bletchley Park tasked with the solution of German Army and Air Force Enigma machine ciphers Hut 8 was a section at Bletchley Park (the British World War II Codebreaking station tasked with solving German naval Enigma messages PC Bruno was a Polish - French intelligence station that operated outside Paris during World War II. ULTra ("Urban Light Transport" is a Personal rapid transit system from Advanced Transport Systems Ltd a company based in Cardiff, Wales. In Cryptography, a cipher (or cypher) is an Algorithm for performing Encryption and Decryption &mdash a series of well-defined steps A machine is any device that uses Energy to perform some activity More precisely, Enigma was a family of related electro-mechanical rotor machines, comprising a variety of different models. In Cryptography, a rotor machine is an electro-mechanical device used for encrypting and decrypting secret messages
The Enigma was used commercially from the early 1920s on, and was also adopted by the military and governmental services of a number of nations—most famously by Nazi Germany before and during World War II. Nazi Germany and the Third Reich are the common English names for Germany under the regime of Adolf Hitler and the National Socialist German Workers World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including 
The German military model, the Wehrmacht Enigma, is the version most commonly discussed. Wehrmacht (literally "defense force" was the name of the unified Armed forces of Germany from 1935 to 1945 The machine has gained notoriety because Allied cryptologists were able to decrypt a large number of messages that had been enciphered on the machine. The Allies of World War II were the countries officially opposed to the Axis powers during the Second World War. See also CategoryCryptographers for an exhaustive list Pre twentieth century Charles Babbage, UK, 19th century Mathematician Cryptanalysis (from the Greek kryptós, "hidden" and analýein, "to loosen" or "to untie" is the study of methods for Decryption was made possible in 1932 by Polish cryptographers Marian Rejewski, Jerzy Różycki and Henryk Zygalski from Cipher Bureau. The Polish people, or Poles, (Polacy) are a Western Slavic Ethnic group of Central Europe, living predominantly in Poland. Marian Adam Rejewski ( 16 August 1905 &ndash 13 February 1980 was a Polish Mathematician and cryptologist who in 1932 solved the Enigma machine Jerzy Witold Różycki (pronounced ['jεʒɨ ru'ʒɨʦki]; Olshana, near Kiev, Ukraine, July 24, 1909 — January Henryk Zygalski ( 1906 - 1978 was a Polish Mathematician and Cryptologist who worked at breaking German Enigma ciphers before and during The Biuro Szyfrów ( Polish for " Cipher Bureau " was the Polish Interwar agency charged with both Cryptography (the In mid-1939 reconstruction and decryption methods were delivered from Poland to Britain and France. Poland (Polska officially the Republic of Poland The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located This article is about the country For a topic outline on this subject see List of basic France topics. The intelligence gained through this source, codenamed ULTRA, was a significant aid to the Allied war effort. Military intelligence (abbreviated MI int Commonwealth, or intel ULTra ("Urban Light Transport" is a Personal rapid transit system from Advanced Transport Systems Ltd a company based in Cardiff, Wales. The exact influence of ULTRA is debated, but a typical assessment is that the end of the European war was hastened by two years because of the decryption of German ciphers. Victory in Europe Day ( V-E Day or VE Day) was May 7 and May 8, 1945, the dates when the World War II Allies 
Although the Enigma cipher has cryptographic weaknesses, in practice it was only in combination with other significant factors (mistakes by operators, procedural flaws, an occasional captured machine or codebook) that Allied codebreakers were able to decipher messages. In Cryptography, a codebook is a document used for implementing a code. 
Like other rotor machines, the Enigma machine is a combination of mechanical and electrical systems. The mechanical mechanism consists of a keyboard; a set of rotating disks called rotors arranged adjacently along a spindle; and a stepping mechanism to turn one or more of the rotors with each key press. Alphanumeric keyboards include Typewriters and Computer keyboards. An 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 The exact mechanism varies, but the most common form is for the right-hand rotor to step once with every key stroke, and occasionally the motion of neighbouring rotors is triggered. The continual movement of the rotors results in a different cryptographic transformation after each key press.
The mechanical parts act in such a way as to form a varying electrical circuit—the actual encipherment of a letter is performed electrically. An electrical network is an interconnection of Electrical elements such as Resistors Inductors Capacitors Transmission lines Voltage When a key is pressed, the circuit is completed; current flows through the various components and ultimately lights one of many different lamps, indicating the output letter. A lamp is a replaceable component such as an Incandescent light bulb, which is designed to produce Light from Electricity. For example, when encrypting a message starting ANX. . . , the operator would first press the A key, and the Z lamp might light; Z would be the first letter of the ciphertext. The operator would then proceed to encipher N in the same fashion, and so on.
To explain the Enigma, we use the wiring diagram on the left. To simplify the example, only four components of each are shown. In reality, there are 26 lamps, keys, plugs and wirings inside the rotors. The current flows from the battery (1) through the depressed bi-directional letter-switch (2) to the plugboard (3). The plugboard allows rewiring the connections between keyboard (2) and fixed entry wheel (4). Next, the current proceeds through the—unused, so closed—plug (3) via the entry wheel (4) through the wirings of the three (Wehrmacht Enigma) or four (Kriegsmarine M4 or Abwehr variant) rotors (5) and enters the reflector (6). The reflector returns the current, via a different path, back through the rotors (5) and entry wheel (4), and proceeds through plug 'S' connected with a cable (8) to plug 'D', and another bi-directional switch (9) to light-up the lamp.
The continual changing of electrical paths through the unit because of the rotation of the rotors (which cause the pin contacts to change with each letter typed) implements the polyalphabetic encryption which provided Enigma's high security. A polyalphabetic cipher is any cipher based on substitution, using multiple substitution alphabets
The rotors (alternatively wheels or drums—Walzen in German) form the heart of an Enigma machine. This article contains technical details about the rotors of the Enigma machine. Approximately 10 cm in diameter, each rotor is a disc made of hard rubber or bakelite with a series of brass spring-loaded pins on one face arranged in a circle; on the other side are a corresponding number of circular electrical contacts. In Geometry, a disk (also spelled disc) is the region in a plane bounded by a Circle. Bakelite (ˈbеɪkɨlaɪt is a material based on the thermosetting Phenol formaldehyde resin polyoxybenzylmethylenglycolanhydride developed in 1907–1909 by Brass 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 The pins and contacts represent the alphabet—typically the 26 letters A–Z (this will be assumed for the rest of the description). An alphabet is a standardized set of letters basic written symbols each of which roughly represents a Phoneme, a Spoken language, either When placed side-by-side, the pins of one rotor rest against the contacts of the neighbouring rotor, forming an electrical connection. Inside the body of the rotor, a set of 26 wires connects each pin on one side to a contact on the other in a complex pattern. The wiring differs for every rotor.
By itself, a rotor performs only a very simple type of encryption—a simple substitution cipher. In Cryptography, a substitution cipher is a method of Encryption by which units of plaintext are substituted with Ciphertext according to a regular system For example, the pin corresponding to the letter E might be wired to the contact for letter T on the opposite face. The complexity comes from the use of several rotors in series—usually three or four—and the regular movement of the rotors; this provides a much stronger type of encryption.
When placed in the machine, a rotor can be set to one of 26 positions. It can be turned by hand using a grooved finger-wheel which protrudes from the internal cover when closed, as shown in Figure 2. So that the operator knows the position, each rotor has an alphabet tyre (or letter ring) attached around the outside of the disk, with 26 letters or numbers; one of these can be seen through a window, indicating the position of the rotor to the operator. In early Enigma models, the alphabet ring is fixed; a complication introduced in later versions is the facility to adjust the alphabet ring relative to the core wiring. The position of the ring is known as the Ringstellung ("ring setting").
The rotors each contain a notch (sometimes multiple notches), used to control the stepping of the rotors. In the military versions the notches are located on the alphabet ring.
The Army and Air Force Enigmas came equipped 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. Events 533 - Byzantine general Belisarius defeats the Vandals, commanded by King Gelimer, at the Battle of Year 1938 ( MCMXXXVIII) was a Common year starting on Saturday (link will display the full calendar of the Gregorian calendar. These were marked with Roman numerals to distinguish them: I, II, III, IV and V, all with single notches located at different points on the alphabet ring. Roman numerals are a Numeral system originating in ancient Rome, adapted from Etruscan numerals. This must have been intended as a security measure, but ultimately allowed the Polish Clock Method and British Banburismus attacks. In Cryptography, the clock was a method devised by Polish mathematician-cryptologist Jerzy Różycki, at the Polish General Staff's Cipher Bureau Banburismus was a process invented by Alan Turing at Bletchley Park in England during the Second World War.
The Naval version of the Wehrmacht Enigma had always been issued with more rotors than the other services: at first, six, then seven and finally eight. Wehrmacht (literally "defense force" was the name of the unified Armed forces of Germany from 1935 to 1945 The additional rotors were named 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 reflector and adding a special fourth rotor. The fourth rotor can be one of two types, "Beta" or "Gamma", and never steps, but it can be manually placed in any of the 26 positions.
To avoid merely implementing a simple (and easily breakable) substitution cipher, some rotors turned with consecutive presses of a key. This ensured the cryptographic substitution would be different at each position, producing a formidable polyalphabetic substitution cipher. A polyalphabetic cipher is any cipher based on substitution, using multiple substitution alphabets
The most common arrangement used a ratchet and pawl mechanism. In Mechanical engineering, a ratchet is a device that allows linear or rotary motion in only one direction while preventing motion in the opposite direction In Mechanical engineering, a ratchet is a device that allows linear or rotary motion in only one direction while preventing motion in the opposite direction Each rotor had a ratchet with 26 teeth; a group of pawls engage the teeth of the ratchet. The pawls pushed forward in unison with each keypress on the machine. If a pawl engaged the teeth of a ratchet, that rotor advanced by one step.
In the Wehrmacht Enigma, each rotor had an adjustable notched ring. The five basic rotors (I–V) had one notch each, while the additional naval rotors VI, VII and VIII had two notches. At a certain point, a rotor's notch eventually aligned with the pawl, allowing it to engage the ratchet of the next rotor with the subsequent key press. When a pawl was not aligned with the notch, it simply slid over the surface of the ring without engaging the ratchet. In a single-notch rotor system, the second rotor advanced one position every 26 advances of the first rotor. Similarly, the third rotor advanced one position for every 26 advances of the second rotor. The second rotor also advanced at the same time as the third rotor, meaning the second rotor can step twice on subsequent key presses—"double stepping"—resulting in a reduced period. 
This double stepping caused the rotors to deviate from a normal odometer. An odometer (often known colloquially as a mileometer or milometer) is a device used for indicating Distance traveled by an Automobile or other A double step occurred as follows: the first rotor stepped, and took the second rotor one step further. If the second rotor moved by this step into its own notch-position, the third pawl drops down. On the next step this pawl would push the ratchet of the third rotor and advance it, but pushed into the second rotor's notch, advancing the second rotor a second time in a row.
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 couple of hundred letters, and so there was very little risk of repeating any position within a single message.
To make room for the naval fourth rotors "Beta" and "Gamma", introduced in 1942, the reflector was changed, by making it much thinner and the special thin fourth rotor was placed against it. No changes were made to rest of the mechanism. Since there were only three pawls, the fourth rotor never stepped, but could be manually set into one of its 26 positions.
When pressing a key, the rotors stepped before the electrical circuit is connected.
The entry wheel (Eintrittswalze in German), or entry stator, connects the plugboard, if present, or otherwise the keyboard and lampboard, to the rotor assembly. The stator is the stationary part of an Electric generator or Electric motor. A plugboard, or control panel, was a device used to direct the operation of Unit record equipment, some cypher machines and some early computers While the exact wiring used is of comparatively little importance to the security, it proved an obstacle in the progress of Polish cryptanalyst Marian Rejewski during his deduction of the rotor wirings. Poland (Polska officially the Republic of Poland Marian Adam Rejewski ( 16 August 1905 &ndash 13 February 1980 was a Polish Mathematician and cryptologist who in 1932 solved the Enigma machine The commercial Enigma connects the keys in the order of their sequence on the keyboard: QA, WB, EC and so on. However, the military Enigma connects them in straight alphabetical order: AA, BB, CC etc. It took an inspired piece of guesswork for Rejewski to realise the modification, and he was then able to solve his even more inspired equations. An equation is a mathematical statement, in symbols, that two things are exactly the same (or equivalent
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. Events 996 - Emperor Otto III issues a deed to Gottschalk Bishop of Freising which is the oldest known document using the name Ostarrîchi Year 1937 ( MCMXXXVII) was a Common year starting on Friday (link will display the full calendar of the Gregorian calendar. A third version, Umkehrwalze C was used briefly in 1940, possibly by mistake, and was solved by Hut 6. Hut 6 was a wartime section of Bletchley Park tasked with the solution of German Army and Air Force Enigma machine ciphers  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. Events 366 - The Alamanni cross the frozen Rhine River in large numbers invading the Roman Empire. Year 1944 ( MCMXLIV) was a Leap year starting on Saturday (link will display full calendar of the Gregorian calendar.
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—"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.
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.
A feature that was used on the M4 Enigma was the "Schreibmax", a little printer 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 lightbulbs 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 plaintext information. In Cryptography, plaintext is the information which the sender wishes to transmit to the receiver(s
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 nothing simply emulating the 9 stecker wires with plugs.
The Enigma transformation for each letter can be specified mathematically as a product of permutations. In several fields of Mathematics the term permutation is used with different but closely related meanings Assuming a three-rotor German Army/Air Force Enigma, let P denote the plugboard transformation, U denote the reflector, and L,M,R denote the actions of the left, middle and right rotors. Then the encryption E can be expressed as
After each key press the rotors turn, changing the transformation. For example, if the right hand rotor R is rotated i positions, the transformation becomes ρiRρ − i, where ρ is the cyclic permutation mapping A to B, B to C, and so forth. A cyclic Permutation is built from one or more sets of elements in Cyclic order. Similarly, the middle and left-hand rotors can be represented as j and k rotations of M and L. The encryption function can then be described as:
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 Park, and were assigned codenames, such as Red, Chaffinch and Shark. Bletchley Park, also known as Station X, is an estate located in the town of Bletchley, in Buckinghamshire, and (since 1967 part of Milton Keynes A code name or cryptonym is a word or name used clandestinely to refer to another name or word 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 key in modern terms) must have been established beforehand, and were distributed in codebooks. In Cryptography, a key is a piece of information (a Parameter) that determines the functional output of a cryptographic algorithm In Cryptography, a codebook is a document used for implementing a code.
An Enigma machine's initial state, the cryptographic key, has several aspects:
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 10114 (approximately 380 bits); with known wiring and other operational constraints, this is reduced to around 1023 (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 attack. In Cryptanalysis, a brute force attack is a method of defeating a Cryptographic scheme by trying a large number of possibilities for example possible keys
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 vector 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. In Cryptography, an initialization vector ( IV) is a block of bits that is required to allow a Stream cipher or a Block cipher to be executed In Cryptanalysis, frequency analysis is the study of the frequency of letters or groups of letters in a Ciphertext. 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—"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 this 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. By 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 used only to set up the rotors and ring settings. For each message, the operator selected a random start position, let's say WZA, and 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 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. More details on Kurzsignale on German U-Boats
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 in several parts, each using its own message key. For more details see Tony Sale's translations of "General Procedure" and "Officer and Staff procedure". 
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.
On 23 February 1918 German engineer Arthur Scherbius applied for a patent for a cipher machine using rotors, and, with E. Events 1455 - Traditional date for the publication of the Gutenberg Bible, the first Western Book printed from Movable Year 1918 ( MCMXVIII) was a Common year starting on Tuesday (link will display the full calendar of the Gregorian calendar (or a Common Arthur Scherbius ( 20 October 1878 &ndash 13 May 1929) was a German Electrical engineer who patented an invention for a mechanical cipher 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. Events 455 - Roman military commander Avitus is proclaimed Emperor of the Western Roman Empire. Year 1923 ( MCMXXIII) was a Common year starting on Monday (link will display the full calendar of the Gregorian calendar.
Chiffriermaschinen AG began advertising a rotor machine—Enigma model A—which was exhibited at the Congress of the International Postal Union in 1923 and 1924. The Universal Postal Union ( UPU, French: Union postale universelle) is an International organization that coordinates postal policies among member The machine was heavy and bulky, incorporating a typewriter. A typewriter is a mechanical or Electromechanical device with a set of "keys" that when pressed cause characters to be printed on a medium 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 Sweden, the Netherlands, United Kingdom, Japan, Italy, Spain, United States, and Poland. "Sverige" redirects here For other uses see Sweden (disambiguation and Sverige (disambiguation. The Netherlands ( Dutch:, ˈnedərlɑnt is the European part of the Kingdom of the Netherlands, which consists of the Netherlands the Netherlands The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located For a topic outline on this subject see List of basic Japan topics. Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest Spain () or the Kingdom of Spain (Reino de España is a country located mostly in southwestern Europe on the Iberian Peninsula. The United States of America —commonly referred to as the Poland (Polska officially the Republic of Poland
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 (Reichswehr) had introduced their own version of the Enigma—the Enigma G, revised to the Enigma I by June 1930. Events 1099 - First Crusade: Christian soldiers take the Church of the Holy Sepulchre in Jerusalem after the final Year 1928 ( MCMXXVIII) was a Leap year starting on Sunday (link will display full calendar of the Gregorian calendar. The Reichswehr ( German for "National Defence" formed the military organisation of Germany from 1919 until 1935 when it was  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 railways), both before and during World War II. The Deutsche Reichsbahn ( DR, "German Reich Railway" – was the name of the German national railway created from the railways of the individual World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including 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). Events 1327 - Teenaged Edward III is crowned King of England, but the country is ruled by his mother Queen Year 1942 ( MCMXLII) was a Common year starting on Thursday (the link will display the full 1942 calendar of the Gregorian calendar. 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. During 1933, Polish codebreakers 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 jam frequently. 
The Abwehr used the Enigma G (the Abwehr Enigma). The Abwehr was a German intelligence organization from 1921 to 1944 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 War. The Spanish Civil War was a major conflict in Spain that started after an attempted Coup d'état committed by parts of the army against the government of 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.
The Enigma wasn't perfect, especially after the Allies got hold of it, thus allowing the Allies to decode the German messages, which proved vital in the Battle of the Atlantic.
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. 
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 museums in the U. A museum is a "permanent institution in the service of society and of its development open to the public which acquires conserves researches communicates and exhibits the S. and Europe. The Deutsches Museum in Munich has both the three and four-wheel German military variants, as well as several older civilian versions. The Deutsches Museum (German Museum in Munich, Germany, is the world's largest Museum of Technology and Science, with approximately Munich (München; Minga is the capital city of Bavaria, Germany. A functional Enigma is on display in the NSA's National Cryptologic Museum at Fort Meade, Maryland, where visitors can try their hand at encrypting messages and deciphering code. The National Security Agency/ Central Security Service ( NSA/CSS) is a cryptologic intelligence agency of the United States government The United States National Cryptologic Museum is a museum of cryptologic history affiliated with the National Security Agency (NSA Fort George G Meade, located adjacent to Odenton, Maryland, in Anne Arundel County, is an active U The Armémuseum in Stockholm in Sweden currently has an Enigma on display. The Swedish Army Museum (Armémuseum is a Museum of Military history located in the district of Östermalm in Stockholm. ('stɔkhɔlm is Sweden 's Capital and its largest City. It is the site of the national Swedish government, the parliament, and the There are also examples at the Computer History Museum in the United States, at Bletchley Park in the United Kingdom, at the Australian War Memorial, and in foyer of the Defence Signals Directorate, both located at Canberra in Australia, as well as a number of other locations in Germany, the U. The Computer History Museum is a Museum established in 1996 in Mountain View California, when The Computer Museum (TCM in Boston) Bletchley Park, also known as Station X, is an estate located in the town of Bletchley, in Buckinghamshire, and (since 1967 part of Milton Keynes The Australian War Memorial is Australia 's national memorial to the members of all its armed forces and supporting organisations who have died or participated Defence Signals Directorate (DSD is an Australian government Intelligence agency responsible for Signals intelligence (SIGINT and Information Canberra ( is the capital city of Australia With a population of over 340000 it is Australia's largest inland City. 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 University Library. History Established on March 13 1897 San Diego State University first began as the San Diego Normal School intended to educate local future female elementary school teachers 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. Events 527 - Byzantine Emperor Justin I names his nephew Justinian I as co-ruler and successor to the throne 2000 ( MM) was a Leap year that started on Saturday of the Common Era, in accordance with the Gregorian calendar. 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 Paxman, but three rotors were missing. Jeremy Dixon Paxman (born 11 May 1950) is an English Journalist, Author and Television presenter. In November 2000, an antiques dealer named Dennis Yates was arrested after telephoning The Sunday Times to arrange the return of the missing parts. The Sunday Times is a Sunday Broadsheet Newspaper distributed in the United Kingdom and Republic of Ireland. 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.
The Enigma was influential in the field of cipher machine design, and a number of other rotor machines are derived from it. The British Typex was originally derived from the Enigma patents; Typex even includes features from the patent descriptions that were omitted from the actual Enigma machine. In the History of cryptography, Typex (alternatively Type X or TypeX) machines were British cipher machines used from 1937. 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 Friedman designed the M-325, a machine similar to Enigma in logical operation, although not in construction. William Frederick Friedman ( September 24, 1891 &ndash November 12, 1969) was a US Army cryptologist. In the History of cryptography, M-325, also known as SIGFOY, was an American Rotor machine designed by William F
A unique rotor machine was constructed in 2002 by Netherlands-based Tatjana van Vark. The Netherlands ( Dutch:, ˈnedərlɑnt is the European part of the Kingdom of the Netherlands, which consists of the Netherlands the Netherlands 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. 
The play, Breaking the Code, by Hugh Whitemore is about the life and death of Alan Turing, who was the central force in breaking the Enigma in Britain during World War II. Alan Mathison Turing, OBE, FRS (ˈt(jʊ(ərɪŋ (23 June 1912 &ndash 7 June 1954 was an English Mathematician The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including Turing was played by Derek Jacobi, who also played Turing in a 1996 television adaptation of the play. Sir Derek George Jacobi CBE (ˈdʒækəbi born 22 October, 1938) is an English Actor and Film director, knighted 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 Enigma codebreaking effort.
Robert Harris' 1996 novel Enigma is set against the backdrop of World War II Bletchley Park and cryptologists working to read Naval Enigma in Hut 8. Robert Dennis Harris (born March 7, 1957 in Nottingham) is a best-selling English Novelist. Bletchley Park, also known as Station X, is an estate located in the town of Bletchley, in Buckinghamshire, and (since 1967 part of Milton Keynes Hut 8 was a section at Bletchley Park (the British World War II Codebreaking station tasked with solving German naval Enigma messages The book, with significant changes in the story, was made into the 2001 film, Enigma, directed by Michael Apted and starring Kate Winslet and Dougray Scott; the film has been criticized for many historical inaccuracies and neglecting the role of Biuro Szyfrów in breaking the Enigma code. Enigma is a 2001 film set in World War II. It stars Dougray Scott and Kate Winslet and is based on the novel Enigma Michael David Apted, CMG (born 10 February 1941) is an English director, producer, writer and Actor Kate Elizabeth Winslet (born 5 October 1975 is a five-time Academy Award -nominated Golden Globe -nominated Emmy Award -nominated Dougray Scott (born 25 November 1965) is a Scottish television and film actor The Biuro Szyfrów ( Polish for " Cipher Bureau " was the Polish Interwar agency charged with both Cryptography (the An earlier Polish film dealing with the Polish aspects of the subject was the 1979 Sekret Enigmy (The Enigma Secret). 
Neal Stephenson's novel Cryptonomicon also features World War II military cryptography, including the Enigma and Bletchley Park. Neal Town Stephenson (born October 31, 1959) is an American writer known primarily for his Science fiction works in the Postcyberpunk genre Cryptonomicon is a 1999 novel by Neal Stephenson. It concurrently follows the exploits of World War II -era Cryptographers affiliated with It takes considerable historical liberties.
The 1989 Doctor Who story The Curse of Fenric features British cryptographers, including a character based on Alan Turing, using a similar device called ULTIMA that is ultimately used to decrypt ancient Viking runes and unleash a plague of vampires. Doctor Who is a British science fiction television programme produced by the BBC. The Curse of Fenric is a serial in the British Science fiction television series Doctor Who, which was first broadcast Alan Mathison Turing, OBE, FRS (ˈt(jʊ(ərɪŋ (23 June 1912 &ndash 7 June 1954 was an English Mathematician
An interactive fiction game Jigsaw by Graham Nelson contains a puzzle in which the player must decrypt a message with a simplified version of the Enigma. Jigsaw is an Interactive fiction (IF game written by Graham Nelson in 1995. Graham A Nelson (born 1968 is a British mathematician poet and the creator of the Inform design system for creating Interactive fiction (IF games The puzzle is generally accepted as the most annoying in the game, which is perhaps some measure of how hard it was to decrypt messages produced by the original machine(s).
Jonathan Mostow's 2000 film U-571 describes a fictional patrol by American submariners who have hijacked a German submarine to obtain an Enigma machine. Jonathan Mostow (born November 28, 1961, Woodbridge CT) is an American Film director, writer and producer U-571 is a 2000 film directed by Jonathan Mostow, and starring Matthew McConaughey, Bill Paxton, Harvey Keitel, The machine used in the film was an authentic Enigma obtained from a collector. The historical liberties taken are large, for the Polish breaks into Enigma (beginning in December 1932) did not require a captured machine, the Royal Navy captured several Enigmas or parts before the U.S. entered the war, and the U. Poland (Polska officially the Republic of Poland The Royal Navy of the United Kingdom is the oldest of the British armed services (and is therefore known as the Senior Service) The United States of America —commonly referred to as the S. capture of a U-boat occurred only days before D-Day in 1944. D-Day may also refer to Decimal Day in the United Kingdom. D-Day is a term often used in Military parlance to denote The film caused considerable protests when it was released in Britain, since it effectively transferred the exploits of the real life HMS Bulldog to a fictional American boat. See also U-571 - the movie U505
Friedrich Kittler's 1986 (trans. Friedrich A Kittler (born 1943 in Rochlitz, Saxony) is a literary scientist and a media theorist 1999) Gramophone, Film, Typewriter examines the use of the Enigma and similar devices in relation to the Symbolic order of Jacques Lacan. The Symbolic order is a part of the psychoanalytic theory of Jacques Lacan. Jacques-Marie-Émile Lacan (French ʒak lakɑ̃ ( April 13, 1901 &ndash September 9, 1981) was a French Psychoanalyst
Wolfgang Petersen's 1981 film Das Boot includes an Enigma machine which is evidently a four-rotor Kriegsmarine variant. Das Boot (das boːt German for The Boat) is a 1981 feature film directed by Wolfgang Petersen, adapted from a novel of the same It appears in many scenes which probably capture well the flavour of day-to-day Enigma use aboard a World War II U-Boat. World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including
The Beast, the online puzzle-solving alternate reality game (ARG) created by a team at Microsoft to promote the Steven Spielberg film A.I.: Artificial Intelligence, required players to use an online Enigma simulator to solve one of the puzzles. The Beast was an Alternate reality game (ARG created by a team at 42 Entertainment to promote the Steven Spielberg film A An alternate reality game ( ARG) is an interactive Narrative that uses the real world as a platform often involving multiple media and game elements to tell Microsoft Corporation is an American multinational Computer technology Corporation, which rose to dominate the Home computer Steven Allan Spielberg, KBE (Hon (born December 18 1946 is an American Film director, Screenwriter and producer.
Stefan Ruzowitzky's 2001 film All the Queen's Men dispenses a mismatched team of British Special Services agents led by an American (Matt LeBlanc) must infiltrate, in disguise, a female-run Enigma factory in Berlin and bring back the decoding device that will end the war. Stefan Ruzowitzky (born December 25, 1961 in Vienna) is an Academy Award -winning Austrian Film director and Screenwriter All the Queen's Men is a 2001 comedy war Film. It was directed by Stefan Ruzowitzky and stars Matt LeBlanc and Eddie Matthew Stephen LeBlanc (born July 25, 1967) is an Emmy and Golden Globe Award -nominated American Actor, best known for
A Java applet is an Applet delivered in the form of Java bytecode. A Java applet is an Applet delivered in the form of Java bytecode. A Java applet is an Applet delivered in the form of Java bytecode. Ruby is a dynamic, reflective, general purpose Object-oriented programming language that combines syntax inspired by Perl with Smalltalk KDE ( K Desktop Environment) (ˌkeɪdiːˈiː is a Free software project which aims to be a powerful system for an easy-to-use Desktop environment.