These pairings are specified as part of the key material. The steckerverbindungen (plugboard) is an added layer of security which consists of 13 wires which plug into into sockets on the front of the enigma machine.Įach wire connects 2 letters e.g. With a ring setting of 'B' (or 2), rotor I's substitution looks like this: ZABCDEFGHIJKLMNOPQRSTUVWXYĮKMFLGDQVZNTOWYHXUSPAIBRCJ The Steckerverbindungen § With a ring setting of 'A' (or 1), rotor I's substitution looks like this: ABCDEFGHIJKLMNOPQRSTUVWXYZ The ringstellung provide the capability of shifting the substitution cipherĪs follows.
In the previous discussion I have assumed that each rotor's simple substitution cipher was fixed. 'FAM' (or alternativelyĪs numbers between 1 and 26, representing the letters). The Ringstellung (ring settings) are generally provided as a 3 letter string e.g. Means the machines period is not 26x26x26, but only 26x25x26. However, when the 3rd (left most) rotor steps, it causes the second rotor to step also. This is not noticed when the second rotor steps, since the first rotor stepsĮvery key press. There is one extra confounding detail, that of 'double stepping'. Used in the Wermacht enigma, later more rotors were added which had two notches. Rotor I causes the next rotor to step on transition from Q to R, rotor II on the transition E to F etc. Each rotor has a notch which causes the rotor Incrementing The Rotors §Ī common mistake when implementing the enigma is assuming the rotors act as a standard odometer, there are however a few key differences. If the rotor start positions are 'FEQ', then they will first be incremented to 'FER' before theįirst letter is enciphered. Is the fact that the rotors increment before each letter is enciphered. One important step that I have not yet mentioned We can see from the table that after the enciphered letter comes back out rotor III at the end, we are left with the letter U. Of the reflector, the letter is sent back through the rotors in the reverse direction (this means the inverse substitution is applied).
ENIGMA SIMULATOR C FULL
This is best depicted using a table (for a full description of the rotor wirings for each rotor, see this wikipedia page): IIIĪfter the letter goes through rotors III,II,I it then hits the reflector and undergoes another simple substitution. The letter 'B' is now input through rotor II, where it is replaced by 'J' etc. So after the letter 'A' goes through the rotor, itĬomes out as a 'B'. ABCDEFGHIJKLMNOPQRSTUVWXYZī is replaced with D, C is replaced with F etc. The substitution table for rotor III can be seen below. Each rotor applies a simple substitution operation. Since our rotors are I,II,III moving from left to right, the character A will first go through rotor III. We will assume for now that as the letter 'A' is encipheredĮach rotor is in its start position ('AAA'). The Rotors §Īssume that our rotors are I,II,III moving from left to right, and we are trying to encipher the letter 'A'. Steckerverbindungen, or plug board settingsįor information on the procedures used by the Germans during WW2 when sending Engima messages, including how the indicators were set, see this description.The 'key' for the enigma consists of several elements: This section will talk about the Enigma I aka Wehrmacht Enigma, other variants are similar in operation. If you would like to encrypt some of your own Enigma messages, have a look at the javascript example. A variety of different models of Enigma were produced, but the German military model, the Wehrmacht Enigma, is the version most commonly discussed. It 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. The first Enigma machine was invented by a German engineer named Arthur Scherbius at the end of the first world war. The Enigma is one of the better known historical encryption machines, and it actually refers to a range of The Enigma cipher was a field cipher used by the
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