The ENIGMA is an electromechanical rotor cryptographic machine, which was used in the Second World War in communications of the German military. The word "„Enigma comes from the Greek one and means mysteries.

History

As an inventor of the ENIGMA the German electrical engineer Dr. Arthur Scherbius (1878-1929) is considered, who announced a patent (DRP 416,219) for this on 23 February 1918. The manufacturing of the machine the cipher machine corporation in Berlin on 9 July 1923 (W.35 Steglitzerstr became. 2) based. The ENIGMA was conceived and commercially on fairs - like 1923 on the international congress of post office in Berne - for the purchase was offered first as civilian coding system. Toward end of the 20's showed military places strengthens interest, so that the machine disappeared soon thereafter from the civilian market. Straight in the upswing of the up to then rather sluggishly running selling had an accident Scherbius with an exit with its Pferdekut deadly. In the year 1934 Dr. Rudolf Heimsoeth and Elsbeth Rinke acquired the former company Scherbius, who continued the manufacturing of the ENIGMA in Berlin under the new company name Heimsoeth & Rinke. The National Socialist rule had already begun. Since in the course of armament a reliable coding system was used, stood to the triumphant advance of the ENIGMA now nothing more in the way.

One estimates that during the Second World War more than 30,000 machines were produced. In the course of the time up to the end of war 1945 and many different models and variants of the ENIGMA came still beyond that to the employment. The probably most spread is the ENIGMA I (speak: "„Enigma unity "“), which was used later starting from 1930 by the realm resistance and by the armed forces and which probably embodies during the Second World War at the most frequent used key procedure.

Principle

The ENIGMA I looks at first sight like a typewriter. It essentially consists of the keyboard, a Walzensatz of three exchangeable rollers (rotors) as well as a lamp panel to the announcement. The Walzensatz is the heart for coding. The three rollers are arranged swivelling and point to both sides in each case 26 electrical contacts to (per one for everyone of of the 26 letters of the alphabet), which by 26 wires inside the roller in (at that time) top secret way with one another are connected in pairs, for example (roller III) contact A with B, B with D, and so on. If one presses a character key, then electric current flows of into the ENIGMA battery present over the pressed key by the Walzensatz and lets an indicator light light up. The lighting up letter corresponds to the coding of the pressed letter. Since with each depressing the key the rollers keep turning themselves similarly as with a mechanical odometer, the key alphabet changes after each letter.

If one enters "„OTTO "“, then successively for example the lamps light up "„PQWS "“. Important and cryptographically strong it is that, differently than with simple monoalphabetical coding systems, with which a plain language letter is always transformed into the same secret text letters (one speaks of "„a "“alphabet), with which ENIGMA are used due to the rotation of the rollers many different alphabets for the coding. This is called polyalphabetische coding. If the rollers of the ENIGMA would not turn, then one would get a simple monoalphabetical coding also with it only.

Structure

Right from the Walzensatz the entrance roller (stator) is, which does not turn and whose contacts are connected with the character keys by 26 wires (in the principle sketch right only four of it are drawn). Left from the Walzensatz the Umkehrwalze (UKW) is, which is likewise certain. With it it concerns an invention (DRP 452,194, announced to 21. March 1926) of Willi grain, a coworker of Scherbius. It points only on its right page 26 contacts to (in the sketch again only four of it are drawn in), which are connected in pairs with one another. The Umkehrwalze causes that the river, which flows through the Walzensatz first from right to left is returned and it again, now from left to right goes through. The river leaves the Walzensatz (as he came) again over the entrance roller.

The table shows the Verdrahtungsschema with the ENIGMA I available five swivelling rollers (I to V) and both the Umkehrwalzen (B and C):

        A B C D E F G H I J K L M N O P Q R S T U V W X Y Z I E K M F L G D Q V Z N T O W Y H X U S P A I B R C J II A J D K S I R U X B L H W T M C Q G Z N P Y F V O E III B D F H J L C P R T X V Z N Y E I W G A K M U S Q O IV E S O V P Z J A Y Q U I R H X L N F T G K D C M W B V V E.G.R G I T Y U P S D N H L X A W M J Q O F E C K

UKW B AY BR CU DH EQ TELEX GL IP JX KN MO TZ VOLKSWAGEN UKW C AF BV CP DJ EGG GO HY KR LZ MX SIZE QT CSU 

At the equipment front a plug board with double-pole socket contacts for each of the 26 letters is attached. The river of the character key is led, before it reaches the entrance roller, across this plug board. After going through and releaving of the Walzensatzes he flows second time over the plug board and finally brings one of the 26 letter lamps to lighting up. The letter lamps as well as the keyboard and the socket contacts are similar as arranged with a German typewriter keyboard:

Q W E R T Z U I O A S D F G H J K P Y X C V B N M L 

Function

With a pressed character key (for example A) the connection to the plug board is switched instead of on the indicator light to the battery. The river supplied by the battery flows in such a way over the pressed key to the plug board. There if the socket A is connected with another socket by a cable attached from the outside ("„gesteckert "“), then A is exchanged with another letter, for example J. If no cable is put ("„ungesteckert "“), then the river arrives directly at the contact A of the entrance roller.

During the further description of the function on the picture "„current flow "“(first only upper half) purchase is taken. It serves only for the illustration and is a simplified representation (rotary) of the Walzensatzes (with left, middle and right rotor) and (static) the Umkehrwalze (Reflector). For clarity reasons in the sketch the number of letters of 26 to 8 (only A to H) was reduced.

The river is led over the entrance roller (it is not drawn in in the sketch) to the entrance contact A of the right roller. Their wiring causes a permutation (permutation) of the letter. The river, which occurs at the entrance contact A from right, leaves the roller on of them left side for example at the output contact B. by the right roller A into B is in such a way converted.

The river arrived now over the contact B into the middle roller and is again permutated by their wiring. Quite possible it is also that with a roller (as in the picture) an entrance contact is connected with the output contact of the same name. Then it remains with B. the river leaves here over the contact B the middle roller and occurs the left roller. Their wiring ensures for the fact that the river of the entrance contact B, as here, to the output contact D is led.

The river went through now all three (swivelling) rollers once and reached the Umkehrwalze. It has only contacts on the right side and connects the letters, for example in pairs D with E.

Now the river second flows time by the Walzensatz, now however from left to right. By the Umkehrwalze it arrives over the contact E into the left roller. Here for example E with C is wired. Therefore the river of far over contact C flows into the middle roller, leaves it again over the contact F and flows into the right roller. The river finally leaves the right roller at the contact G.

The further current flow comes out from the sketch not, is however easily avowed. After withdrawal from the Walzensatz the river is led over the entrance roller back to the plug board. If the letter G with another letter is here gesteckert, then a last permutation takes place. If G is ungesteckert, the lamp G lights up. (It lights up by the way only so long, as the key A is kept pressed, since only with pressed key the two-way contact is switched to the battery. If one releases it, the lamp G. expires) in the described example the letter A (its key was initially pressed and is still pressed) as letter G is thus coded.

If the text which can be coded reads "„AACHENISTGERETTET "“, again a A is to be entered. Thus the key A is released and pressed for the second time. It is important that with the mechanical pressure on the key with the help of an incrementing mechanism the right roller around a position one rotates at the same time. (The middle roller rotates only after 26 steps of the right roller.) in the lower half of the picture "„current flow "“the situation is outlined, after the right roller kept turning itself around a position (downward).

As one can recognize by the sketch, the path for again at the contact the river occurring changed A of the right roller radically. It now takes also with the middle and left roller as well as the Umkehrwalze completely different way than before, although these rollers did not turn. The result is another coding letters of the A, which is converted now into C.

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