The Caesar Cipher : Old But Gold

  Around 58 before the common era (BCE), the first well known cipher, a substitution cipher, was used by Julius Caesar. It is now called Caesar Cipher. How does Caesar work? Caesar shifted each letter in his military commands in order to make them appear meaningless should the enemy intercept it. Just imagine, if I and him decided to communicate using the Caesar Cipher First. We would need to agree in advance on a shift to use, let’s say six. To encrypt his message, He must shift six to each letter in his real message. If I put the word “Air”, then it'll change to “Gox”. Letter A shifts six to G, 1(B), 2(C), 3(D), 4(E), 5(F), 6(G), so we use G as A-- So complicated, right. After receiving the message, I simply subtracted the shift of three from each letter in order to read the real message. This basic cipher was used by military leaders for hundreds of years after Caesar, incredible!

  We know that Caesar Cipher is good to communicate with its unique characteristics. However, a lock breaker may look for mechanical flaws. What if it fails? We can extract information to narrow down the correct combination. Fyi, the process of key breaking and code breaking are very similar. Al-Kindi was an Arabic mathematician who found the weakness of the Caesar Cipher. He was able to discover this weakness because he was given a miracle by God. Just kidding, actually he broke the Caesar Cipher by using a clue based on an important property of the language used to write a message. We can try to scan text from any book and then count the frequency of each letter. With using this method, we will find a fairly consistent pattern. Did you know? Codebreaker uses this clue as their most valuable tool . They count up the frequencies of each letter in the encrypted text. Here’s the key, they will check how far the letter has shifted. Codebreakers reverse the shift that they have been seen in order to reveal the real message. We can call it frequency analysis and it's detrimental to the security of Caesar's cipher.