The Enigma cipher was a field cipher used by the Germans during World War II. Enigma is one of the most famous encryption machines in history. The first Enigma machine was invented by a German engineer named Arthur Scherbius at the end of World War I. It was used commercially from the early 1920s and was also used by the military and government services of a number of countries, including Germany, before and during World War II to transmit coded messages. Many different Enigma models have been produced, but the German military model and the German "Enigma" cipher are the most famous and discussed.
Cracking the Enigma cipher during World War II
Some historians believe that the breaking of the Enigma cipher was the most important victory for the Allied powers during World War II. The Enigma machine allowed for billions of ways to encode messages, making it incredibly difficult for other countries to break German codes during World War II. For a while the code seemed invulnerable. Then Alan Turing andother researchers exploited several flaws in the implementation of the Enigma code and gained access to German code books, allowing them to create a machine called the Bombe. She helped break the most difficult versions of Enigma. Poland in 2007 issued a coin in honor of the 75th anniversary of the breaking of the Enigma cipher - 2 złoty from northern gold. In the center is the coat of arms of Poland, and in a circle there is an Enigma wheel-relle.
The meaning of breaking the cipher for allies
Some historians believe that the Enigma hack was the single most important victory for the Allied Powers during World War II. Using the information they deciphered from the Germans, the Allies were able to prevent many attacks. But to avoid suspicion that they found a way to decipher the messages, the Allies had to allow some attacks, despite the fact that they had the knowledge to stop them. This is described in the film "The Imitation Game", released in 2014.
Machine "Enigma": description, components
The Enigma machine consists of several parts, including the keyboard, board, rotors and internal electronic circuits. Some of them have additional features. Encoded messages were a set of letters that turned into a clear sentence when deciphered. Enigma machines use a form of substitution encryption. Substitution encryption is a simple way to encode messages, but such codes are fairly easy to break. But the Enigma machine is designed so that the right rotor advancesone position immediately after pressing the enter key. Thus, the encryption of the letters actually begins while the rotors are in the position preceding AAA. Usually this position is AAZ.
How the Enigma cipher works
A simple example of a substitution encryption scheme is the Caesar cipher. It consists in changing the place of each letter of the alphabet. For example, when shifted by 3 places, the letter A will take the place of G. But the Enigma machine cipher was undoubtedly much more powerful than the simple Caesar cipher. They use a form of substitution ciphers, but each time a letter was matched against another, the whole encoding scheme changed. Variants of Enigma ciphers - in the photo below.
After pressing each button, the rotors move and direct the current in a different path to another open letter. Thus, for the first keystroke, one encoding is generated, and for the second keystroke, another. This greatly increases the number of possible coding options, because every time a key is pressed on the Enigma machine, the rotors turn and the code changes.
The principle of the Enigma machine
When a key is pressed on the keyboard, one or more rotors move to form a new rotor configuration that will encode one letter as another. Current flows through the machine and one light on the lamp board lights up to indicate the output letter. An example of an Enigma cipher looked like this: if the P key is pressed, and the Enigma machine encodes this letter as A, onthe lamp panel will illuminate A. Each month, Enigma operators received code books that indicated which settings would be used each day.
Encryption scheme
The circuit was similar to an old-fashioned telephone patch panel that has ten wires, with two ends in each wire that can be plugged into a jack. Each plug wire can pair two letters by connecting one end of the wire to one letter slot and the other end to the other letter. The two letters in the pair will swap, so if B is connected to G, G becomes B and B becomes G. This provides an extra layer of encryption for the military.
Message encoding
Each machine rotor has 2626 numbers or letters. The Enigma machine can use three rotors at a time, but these can be changed from five sets, resulting in thousands of possible configurations. The "key" to the Enigma cipher consists of several elements: the rotors and their order, their initial positions, and the displacement scheme. Assuming that the rotors move from left to right, and the letter A is to be encrypted, then when the letter A is encrypted, each rotor is in its original position - AAA. Since the rotors move from left to right, the character A will go through the third one first. Each rotor performs a replacement operation. Therefore, after the character A passes through the third, it comes out as B. Now the letter B is entered through the second rotor, where it is replaced by J, and in the first J is changed to Z. After the Enigma cipher passesthrough all the rotors, it goes to the deflector and goes through another simple replacement.
Key to decrypt messages
After exiting the reflector, the message is sent through the rotors in the opposite direction, with reverse replacement applied. After that, the symbol A will turn into U. Each rotor, on the rim, has an alphabet, so the operator can set a certain sequence. For example, the operator could rotate the first rotor to display D, rotate the second to display K, and rotate the third slot to display P. With the initial set of three numbers or letters displayed on the sender's machine when he began typing the message, the recipient can decode it by setting its identical Enigma machine to the initial sender settings.
Disadvantages of Enigma encryption method
The main disadvantage of the Enigma cipher was that the letter could never be encoded as it is. In other words, A will never be encoded as A. This was a huge flaw in the Enigma code because it provided a piece of information that could be used to decrypt messages. If decoders could guess the word or phrase that would likely appear in the message, this information would help them to decipher the code. Since the Germans always sent the weather message at the beginning and usually included a phrase with their traditional greeting at the end of the message, phrases were found that approximateddecoders to unravel.
Alan Turing and Gordon Welchman's car
Alan Turing and Gordon Welchman developed a machine called the Bombe that used electrical circuitry to decipher an Enigma encoded message in less than 20 minutes. The Bombe machine attempted to determine the rotor settings and Enigma machine circuitry used to send a given coded message. The standard British Bombe vehicle was essentially 36 Enigma vehicles linked together. Thus, she modeled several Enigma machines at once.
What the Bombe looked like
Most Enigma machines had three rotors, and each of the Enigma simulators in Bombe had three drums, one for each rotor. The Bombe's drums were color-coded to match the rotor they were simulating. The drums were arranged so that the top of the three simulated the Enigma's left rotor, the middle one simulated the middle rotor, and the bottom simulated the right rotor. For each full rotation of the upper reels, the middle reels were increased by one position, the same happened with the middle and lower reels, bringing the total number of positions to 17,576 positions of the 3-rotor Enigma machine.
Decoder work
For each rotor configuration, at each turn of the drums, the Bombe machine made an assumption about the circuit setup, for example, that A is connected to Z. If the assumption turned out to be false, the machine rejected it and did not use it again, and did not spend time checkingany of these later. The Bombe machine shifted the rotor positions and chose a new guess and repeats this process until a satisfactory setting arrangement appears. If the machine "guessed" that A was connected to Z, then it understood that B must be connected to E, and so on. If the test did not result in a contradiction, the machine would stop and the decoder would use the selected configuration as the key to the message.
