cryptography and useless mathematics. part 2

A game of imitation without unnecessary details, but with important ones

Until the moment when we are captured by robots, there is still a little time left. Therefore, we will have time to tell you about cryptography in the era of electromechanical devices. And to understand what is happening here, we advise you to read the first part of the article.

Sometimes humanity takes a terrible step into the abyss, only to get out and go forward. War is always a huge abyss. World War II gave impetus to the formation of a new branch of cryptography - electromechanical.

Most of us know what a typewriter looks like. But few would recognize it as the most feared weapon of the twentieth century. This is what the Enigma military cipher machine looked like.

It would be fair to say that "Enigma" was not called a specific machine, but a whole series of machines. They differed in configuration, but served the same purpose - to encrypt. In essence, encryption was still based on a principle familiar to us - a simple substitution cipher. But there were several substitutions, and for each letter the shift was different.

Outwardly, the machine really looked like a typewriter: it was a box with a keyboard and incomprehensible switches. Inside, the magic of chaos was going on. The text was encrypted thanks to rotars - that was the name of the disks inside the Enigma. Each such disk had 26 contacts.

Each rotor took on one letter value and returned another: each rotor performed this operation. The initial letter entered on the machine's keyboard changed its meaning several times, moreover, by a seemingly random, indecipherable number of shifts. The first rotor gave out one cipher, then the second rotor changed it. And so on, until the rotors run out. Usually they ended at three pieces, but sometimes there were four - it depended on the Enigma model.

To further confuse the cipher, a patch panel was invented. It consisted of cells, the number of which corresponded to the number of letters in the alphabet. The cells were connected by a wire and swapped each other's value. By inserting the wire with one end into the “A” socket, and with the other end into the “E”, you swapped these letters. After all these manipulations, the number of possible variants of the cipher became equal to 150738274937250 (two to the 47th degree).

"Enigma" had a very complex principle of operation, but easy execution. It was enough to enter text on the keyboard and see what happened. "Enigma" was a popular device: for the entire time of its existence, about 100 thousand copies of the product were produced. Even then, the story of adding accessories to the device became relevant. For example, one of the configurations allowed the cipher to be displayed on the panel, instead of watching the light bulbs light up. Or use Enigma remotely, though with the help of a wire - then the operator at one end of the wire knew only the message, and at the other - only the cipher. This has become a new element of secrecy.

Bletchley Park has always kept many secrets. Enigma was not the first machine to encrypt messages, it was simply the most famous. And when Enigma was first invented in Germany, deciphering machines were already being built in Britain. True, they are not.

The surprise in The Imitation Game about the huge machine is nothing more than acting. Bletchley Park by that time boasted a car called the Colossus. Already by the name it can be assumed that here the dimensions of the device were really amazing. "Colossius" was a cabinet with switches and light bulbs. It cracked ciphers from intercepted radio broadcasts codenamed "fish" and was decommissioned with the invention of Enigma.

Unfortunately or fortunately, he could only solve narrowly focused tasks and it was necessary to look for something that would cope with Enigma.

And then the Turing Bomb was dropped.

There was no bomb, of course. That was the code name for the machine that defeated Enigma. The Turing machine was of great importance at that time, but no less for us. It was she who laid the foundation for modern computers. But we will talk about this in more detail next time.