Before your secret codes in the playground, before the creation of WhatsApp, Man was already trying to communicate messages accessible to the sender and the recipient alone. In order to prevent these secret messages from falling into the hands of third parties, they invented increasingly complex coding systems using different languages, mathematics and powerful algorithms.
From era to era, new decoding techniques (cryptanalysis) have made previous encryption systems obsolete, creating a need for constant innovation. Today we're talking about three encryption techniques that have become famous: Caesar, Vigenère and Enigma. Are you ready? Let's go!
Caesar's Code
The Caesar cipher is a code that seems quite simple today, but could seem very disconcerting to someone who had never seen one.
It is an alphabetic shift of a given number of letters, also called a “mono-alphabetic substitution cipher system”.
The difficulty here is finding the number of letters of shift to decipher the message, called the “ Caesar Cipher ”. With 26 letters in the Latin alphabet, there are only 26 different encryption keys, which, for a coded message these days, is very weak. It takes its name from the Emperor Julius Caesar who used this system for his secret correspondence, especially military.
But there are much more recent uses for this method: in 1915, the Russian army used this coding system for its troops because it was easy to use. However, German and Austrian analysts had no trouble decoding them thanks to the use of methods such as frequency analysis . There are, however, techniques that make the Caesar code almost impossible to decipher, such as the Vigenère code, which is based on an equivalent principle. Vigenère
The Vigenère Code
If the Caesar code was easy to decipher because it was only a mono-alphabetic substitution encryption system, the Vigenère cipher is much more complex: we are talking here about a poly-alphabetic substitution encryption system.
This method takes its name from Blaise de Vigenère, a French diplomat from the 16th century. This code requires a decryption key. Without this key, it is almost impossible to decipher the code in question, and there can be an infinite number of them (unlike the Caesar code where there are only 26). This key is in the form of a word, a code or even a sentence known by the sender of the message and the recipient. The advantage? This coding technique cannot be solved by frequency analysis. Each character of the message is encrypted using the successive letters of the key with which the substitution is carried out. The longer and more varied the key, the better the secret message is encrypted. In order to encode the message or decipher it, it is also necessary to have on hand a Vigenère table which serves as a support for the substitutions.
The Enigma Code
Throughout history, some have used entire literary works to encode their messages, since it was sufficient that the sender and receiver had the same work in their hands.
If you've ever watched Morten Tyldum's 2014 film Imitation Game or are a fan of World War II stories, you've probably heard of Enigma . Enigma is the name given to an electromagnetic machine used to encrypt and decrypt coded messages.
It was invented in 1919 and was mainly used by Nazi Germany and its allies during World War II because its designers considered it inviolable. How did it work? By typing on a letter, an electric current passed through components called rotors. After a series of complex transfers, the machine indicated which letter corresponded to the letter initially given.
However, when one of these rotors rotated, the flow of electrical current changed completely, resulting in a completely new combination of letters. Since the rotors were moved daily, breaking the code was almost impossible. Almost? Yes. But impossible? No. In January 1939, after years of effort, the French and British (led in particular by cryptanalyst Alan Turing ) managed to reproduce the operation of the machine and thus decipher the messages of the enemy forces. This breakthrough was due to a recurrence detected in each telegram transmitted by the Nazis: the “Heil Hitler” concluding each of their messages.
We now invite you to go to the Dcode website to go faster! Yrxv dyhc wrxw frpsulv? Od foh gx phvvdjh vxlydqw hvw “GhwhfwlyhEra”. Do you have it? Cfxys t zqna ksvf i'dzhmt wmxljtcui! Viu vwyit gbfvxxu g'wix qzrv engwg azgssq ssnv xhcn :)
Too easy for you?
Then we have just the thing for you! The detective in charge of the case of the death of Henry COLEMAN, a student at Woodlock University, needs detectives who can understand these coded messages...
