Question

Use Playfair cipher to encrypt the plaintext “pink balloon” using the key exam.

Answer 1

Firstly we will create a 5 X 5 matrix using key=exam

E	X	A	M	B
C	D	F	G	H
I/J	K	L	N	O
P	Q	R	S	T
U	V	W	Y	Z

Plaintext= pink balloon

Now divide the plain text into pairs of 2 and adding x after first occurence of L so no pair have same characters inside them

Rules:-

Rule 1=if both letters are in same column then take letters below them

Rule 2=if both letters are in same row then take letters right next

Rule 3=if both letters are not in same row ,then create a rectangle with these letters in one corner and take letters of other corners horizontally.

pi	up	Using rule 1
nk	ol	using rule 2
ba	em	using rule 2
lx	ka	Using rule 3,form rectangle using L,K,D,X,A,F,L and take other horizontal corners
lo	ni	Using rule 2
on	io	using rule 2

So ciphet text= upolemkaniio