Beautiful Mind

The Roman conqueror Julius Caesar used an easy substitution cipher for sending his secret messages. He simply replaced each letter with the third letter after it in the alphabet, so that plaintext “a” became ciphertext “d” and plaintext “b” became ciphertext “e”, and so on.

Because it is difficult to remember an incoherent string of 26 letters, cipher alphabets are often based on a single word that is easy to memorize. The simplest method is to write out the keyword, omitting any repeated letters, then to follow it with the remaining letters of the alphabet in order. A keyword should be between five and nine letters long. It must only have one of each letter in it. If you keyword does have more than one of any letter, omit any repeated letters. For example, if your selected keyword was “cookie” you would use “cokie” – leave out the second “o”.

Here is a Substitution Cipher with zebra lips as the keyword.

Based on these methods cryptographers built many algorithms and used as the powerful communication mechanism in the national security organizations.

You can find many novels and books. Dan brown’s “Digital Fortress”, “Da Vinci Code” and Arthur Conan Doyle’s “The Return of Sherlock Holmes” inspired me read more about the cipher text and messages. Some of the links that I found more interesting to read are

THE DANCING MEN

CLASSICAL CRYPTOGRAPHY

CAESAR’S CIPHER I AND II