Cryptography is a fascinating world of secret codes with embedded mysterious messages. The Caesar cipher (also known as the shift cipher) is one such methodology that was first recorded as being used by Julius Caesar during his time of leadership over the Roman Empire. According to the ancient historian Suetonius, Julius Caesar used this cryptic code to send military and sensitive communications throughout the Roman Empire to his generals and political allies. It was perhaps a safe code also, because few 'citizens' were literate in the written language of the time.
Considered one of the most simple symmetric encryption algorithms in the world of secret codes, messages using this process are easy to create and usually very easy to break open.
You create your coded message by shifting the letters of your message over a constant number of alphabetical characters. For example the use of 3 would shift over the letters of 3 alphabetic characters and the letter A would become a D, then the letter B would become an E and so forth. When you reach the end of the alphabet you repeat the count in a cyclic manner.
INTERESTING POINTS to ponder concerning the use of the Caesar cipher include:
The letter E is the most commonly used character in the English language this knowledge leads to and understanding most Caesar codes can be easily broken by checking out which alphabet letter occurs most often in the message. Thus use of a character frequency variable (know as frequency analysis, developed in the Arabian world, 1000 CE) in any encrypted message helps decipher the code.
When using this cipher there is no file size limit on your computer.
In our modern world of computers this simple secret code is also know as, a monoalphabetic substitution cipher, where a cipher character is exchanged for a plaintext letter.
It is an interesting factoid that monoalphabetic substitution ciphers can be historically traced to the 4th century BC.
The 'Kama-Sutra' (Hindu text concerning the sexual life of women) includes a section that describes one of the 64 arts that a woman should know..arranging discreet meetings with a lover, using these simple cryptic messages.
The Caesar cipher was used during the time of the development of the Christian faith to send coded messages to believers who feared persecution and to mark catacomb meeting places.
It was also used on the Mezuzah case and parchment hung at the doorway entrance to Jewish homes. Using the Caesar cipher many of these cases were encrypted with Shaddai meaning G-d. The actual parchment blessing would have other encrypted sayings on it, such as, Adonai, Eloheinu, Adonai meaning The L-d, our G-d, the L-d (The Mysterious Name, by Alexander Poltorak).
The Vigenere algorithm cipher is a modernized version of the Caesar Cipher.
Modern toy makers use the Caesar cipher in various products, such as, secret decoder rings once found in Ovaltine and breakfast cereal boxes.
This type of code is so easy to break it is really not used for any top secret or security messaging these days. Instead it is used commonly on the Internet to post 'dirty jokes' and sometimes offensive opinions you must decode to understand. Sometimes puzzle creators use this type of code (ROT13) to embed answers to riddles or other thinking games on the Internet.
The Caesar cipher is still used today in many ways and places. Just because it is a simple algorithm does not mean it isn't useful. The importance and security of any cipher is not based on the enemy's ignorance of the enciphering algorithm, instead it is based on the ignorance of the decoder and many times their need to look for the more in-depth code schematic.
Suetonius, Life of Julius Caesar