question: How does the enigma bombe work?
comment: It had a small list of common parts of messages. Trying every key, it sought a match. When it found one the key (dial settings etc) were tried on a whole message. If it worked, you had the key for that day's message group.
passages: BULLET::::- Plugboard connections: EJ OY IV AQ KW FX MT PS LU BD
  
  BULLET::::- Reconfigurable reflector wiring: IU AS DV GL FT OX EZ CH MR KN BQ PW
  
  BULLET::::- Indicator groups: lsa zbw vcj rxn
   Section::::The principle of the bombe.
  
  The following settings of the Enigma machine must be discovered to decipher German military Enigma messages. Once these are known, all the messages for that network for that day (or pair of days in the case of the German navy) could be decrypted.
  
  Internal settings (that required the lid of the Enigma machine to be opened)
   Section::::Design.:Reflector.
   The bombe was designed to discover some of the daily settings of the Enigma machines on the various German military networks: specifically, the set of rotors in use and their positions in the machine; the rotor core start positions for the message—the message key—and one of the wirings of the plugboard.
  
  Section::::The Enigma machine.
   Section::::Operation.:Details.
   The British bombe was an electromechanical device designed by Alan Turing soon after he arrived at Bletchley Park in September 1939. Harold "Doc" Keen of the British Tabulating Machine Company (BTM) in Letchworth ( from Bletchley) was the engineer who turned Turing's ideas into a working machine—under the codename CANTAB. Turing's specification developed the ideas of the Poles' "bomba kryptologiczna" but was designed for the much more general crib-based decryption.
   BULLET::::- Gordon Corera, Poland's overlooked Enigma codebreakers, BBC News Magazine, 4 July 2014
  
  BULLET::::- Long-running list of places with Enigma machines on display
  
  BULLET::::- Bletchley Park National Code Centre Home of the British codebreakers during the Second World War
  
  BULLET::::- Enigma machines on the Crypto Museum Web site
  
  BULLET::::- Pictures of a four-rotor naval enigma, including Flash (SWF) views of the machine
  
  BULLET::::- Enigma Pictures and Demonstration by NSA Employee at RSA
  
  BULLET::::- Kenngruppenheft
  
  BULLET::::- Process of building an Enigma M4 replica
  
  BULLET::::- Breaking German Navy Ciphers
  
  BULLET::::- An online Enigma Machine simulator
  
  BULLET::::- Enigma simulation
  
  BULLET::::- Universal Enigma simulator
   Section::::Response to the four-rotor Enigma.:US Navy Bombe.
   The bombe searched for possible correct settings used for an Enigma message (i.e., rotor order, rotor settings and plugboard settings) using a suitable "crib": a fragment of probable plaintext. For each possible setting of the rotors (which had on the order of 10 states, or 10 states for the four-rotor U-boat variant), the bombe performed a chain of logical deductions based on the crib, implemented electromechanically.
   In 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 similar to the other wheels.
   where the letters following each mapping are the letters that appear at the windows at that stage (the only state changes visible to the operator) and the numbers show the underlying physical position of each rotor.
   Bombe
  
  The bombe () is an electro-mechanical device used by the British cryptologists to help decipher German Enigma-machine-encrypted secret messages during World War II. The US Navy and US Army later produced their own machines to the same functional specification, albeit engineered differently both from each other and from Polish and British Bombes.
   Section::::Response to the four-rotor Enigma.
   Discovering the logical structure of the machine may be called "breaking" it, a one-off process except when changes or additions were made to the machines. Finding the internal and external settings for one or more messages may be called "solving" - although breaking is often used for this process as well.
  
  Section::::The Enigma machines.:Security properties.
   In 1944, the "Luftwaffe" introduced a plugboard switch, called the "Uhr" (clock), a small box containing a switch with 40 positions. It replaced the standard plugs. After connecting the plugs, as determined in the daily key sheet, the operator turned the switch into one of the 40 positions, each 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 letters, but simply emulated the 13 stecker wires with plugs.
  
  Section::::Design.:Mathematical analysis.
   The bombe identified possible initial positions of the rotor cores and the "stecker partner" of a specified letter for a set of wheel orders. Manual techniques were then used to complete the decryption process. In the words of Gordon Welchman, "... the task of the bombe was simply to reduce the assumptions of wheel order and scrambler positions that required 'further analysis' to a manageable number".
  
  Section::::The principle of the bombe.:Structure.
   Section::::Design.:Rotors.
   Since the operation of an Enigma machine encoding a message is a series of such configurations, each associated with a single character being encoded, a sequence of such representations can be used to represent the operation of the machine as it encodes a message. For example, the process of encoding the first sentence of the main body of the famous "Dönitz message" to
  
  can be represented as
   Like other rotor machines, the Enigma machine is a combination of mechanical and electrical subsystems. The mechanical subsystem consists of a keyboard; a set of rotating disks called "rotors" arranged adjacently along a spindle; one of various stepping components to turn at least one rotor with each key press, and a series of lamps, one for each letter.
  
  Section::::Design.:Electrical pathway.
   John Whetter and John Pether, volunteers with The National Museum of Computing, bought a Lorenz teleprinter on eBay for £9.50 that had been retrieved from a garden shed in Southend-on-Sea. It was found to be the World War II military version, was refurbished and in May 2016 installed next to the SZ42 machine in the museum's "Tunny" gallery.
  
  Section::::See also.
  
  BULLET::::- Enigma machine
  
  BULLET::::- Siemens and Halske T52
  
  BULLET::::- Turingery
  
  BULLET::::- Combined Cipher Machine
  
  Section::::References.
  
  BULLET::::- in
  
  BULLET::::- in
   Several software implementations exist, but not all exactly match Enigma behaviour. The most commonly used software derivative (that is not compliant with any hardware implementation of the Enigma) is at EnigmaCo.de. Many Java applet Enigmas only accept single letter entry, complicating use even if the applet is Enigma compliant. Technically, Enigma@home is the largest scale deployment of a software Enigma, but the decoding software does not implement encipherment making it a derivative (as all original machines could cipher and decipher).
   BULLET::::- Neal Stephenson's novel "Cryptonomicon" (1999) prominently features the Enigma machine and efforts to break it, and portrays the German U-boat command under Karl Dönitz using it in apparently deliberate ignorance of its penetration.
  
  BULLET::::- Enigma is featured in "The Code Book", a survey of the history of cryptography written by Simon Singh and published in 1999.
  
  BULLET::::- Films
  
  BULLET::::- "Sekret Enigmy" (1979; translation: "The Enigma Secret"), is a Polish film dealing with Polish aspects of the subject.
   The bombe was an electro-mechanical device that replicated the action of several Enigma machines wired together. A standard German Enigma employed, at any one time, a set of three rotors, each of which could be set in any of 26 positions. The standard British bombe contained 36 Enigma equivalents, each with three drums wired to produce the same scrambling effect as the Enigma rotors. A bombe could run two or three jobs simultaneously.
   Section::::The Enigma machine.:Four-rotor Enigma.
   A path from one first letter to the corresponding fourth letter, then from that letter as the first letter to its corresponding fourth letter, and so on until the first letter recurs, traces out a cycle group. The following table contains six cycle groups.
  