Cryptography: The Caesar Cipher

1. In the 58 D.C.
Caesar created the first cipher in the history,
known as the Caesar Cipher.
He wanted to comunicate with his contacts
without any external intrusion.

2. • Caesar shifted the letters in his
military commands, following a
precise logic.
• Before the comunication
begins, he had to determinate
this logic with the receiver.
• For example, with a 3 positions
exchange, an ‘A’ becomes a ‘D’
, and so on…
• The receiver has to return to the
original message with the
reverse function.

3. • After 800 years , Al-Kindi discovered the code breaker for the
Caesar Cipher.
• He just analizes the letter’s frequency of a language, idenfying how
many times a letter is repeated, in a book for example.
• So, if a crypted message, in that language, has a different
frequency, we can discover the shift studying the difference.