Homophonic System
In the substitution system the relation between the text and key is one to one. In this type the relation is one to many (i.e each letter can enciphered in multi images)
Example:-
Plain text letter Cipher text homophonic letters
A 17,19,34,41,56,60,67,83
I 08,22,53,65,88,90
L 03,44,76
N 02,09,15,27,32,40,59
O 01,11,23,28,42,54,70
P 33,91
T 05,10,20,29,45,58,64,78,99
Example:
Plain Text: PILOT
Cipher Text: 91 88 76 70 99
Plain Text : ALL
Cipher Text :19 76 03
vigner cipher
Note : When key length is less than the length of text to be ciphered we repeat the key letters to be equal to the plain text letters.
Plaintext : Computer
Key : sun
We can draw only a partial table containing the key letters as follows
Cipher : The cipher text letters can be found by taking the letters apposing the key letters from the above table as follows
c o m p u t e r
s u n s u n s u
u i z h o g w l (the cipher text)
Decipher:
The key letters are spreaded over the cipher text. When two letters crossected on the same row ,then the letter above the crossection in the outside row is the plaintext letter.