ENCRYPTION METHOD 2- POLYBIUS CIPHER

 

* It is a simple method used in ancient Greek times. It was developed by the      famous historian Polybius(150 BC).
* It is a method that converts  letters to numbers with square  checkboards.
* The original version  is in the form of a 5x5 square (Greek alphabet)
* Square size changes according to the number of letters in the alphabet. For    example, a 7x7 matrix is required for the Japanese alphabet.
* Below you can see to the standart version adapted to the English alphabet  (we will use this). 

*Curriculum topics related to Polybius encryption/ Aim: Matrix,  Probablity,  Permutation

EXAMPLE

* If you want to encrypt the ETWINNING ; 

Only you will change letters with numbers.Every letter  represents where it is located. For example, the letter E is denoted by 15. Similarly, if other letters are replaced with numbers, the cipher text "154452243333243322" is obtained.

Method:Polybius ,Plaintext:ETWINNING, Ciphertext: 154452243333243322

* Cipher texts are also easily deciphered with the help of squares.                                                          

Note: To strengthen the polybius method a little more, the squares can be expanded and numbers can be used. The numbers are often nonfunctional but make the polybius square more stronger.

 

                                                     Extanded of standart version

 

As you can see, this very simple cipher method could not been solved for years. Later times, the mixed polybius method was used to strengthen the polybius cipher.

 

MIXED POLYBIUS CIPHER

Ciphers which have a key are always more  stronger. Because they confuse the order of the letters in the alphabet.

EXAMPLE

İf you want to encrypt  "STAY HEALTHY"  plain text, with POLYBIUS key; 

* Firstly you will write the key in the square.

* Then you will continue other letters of the alphabet and fill the square.( Attantion! use each letter only ones)

* You will get the table below.

 

* Finally you will change each letter with corresponding number. And you will find the cipher text " 23512414 35322413513514" 

Method:Mixed Polybius ,Plaintext:STAY HEALTY, Key: POLYBIUS,

Ciphertext: 23512414 35322413513514

* Cipher texts are also easily deciphered with the help of squares.