The problem with this type of cipher is that since each letter in the plaintext only maps to one letter in the encoded text, it is very easy to break using a technique known as frequency analysis. Using this cipher we could encode the message “HELLO” to “KHOOR” and someone who receives this message could simply decode it by looking up each letter in the encoded text row and mapping it to it’s plaintext value. For example if we want to encode all the letters in the alphabet using a Caesar cipher with an offset of 3, we would simply shift each letter 3 places such that “A” would encode to “D”, “B” to “E” and so on as illustrated in Figure 1.įigure 1: An example of a Caesar cipher with offset 3

In the Caesar cipher, each letter in the plaintext is simply encrypted to a letter in the encoded text according to a predefined offset. A common, and easy to understand monoalphabetic cipher is the Caesar cipher. These ciphers are simple forms of encryption which for a given key, match each letter of the alphabet (or number) in the source text (commonly referred to as the plaintext) to one other character in the encrypted text. Prior the creation of the Vigenère cipher, most encrypted messages were encrypted using different forms of monoalphabetic ciphers. What is a Vigenère cipher? History of the cipher Implementing the Vigenère cipher in python.

How to encode a message using matrix