What will be the ciphered text corresponding to "EXAMPLE" if running key cipher is used for encryption with keyword as "DATASTRUCTURE"?

Solution (By Examveda Team)

Running Key Cipher is a polyalphabetic substitution cipher where a plaintext is combined with a keyword to generate a ciphered text. The keyword is usually a long text that matches or exceeds the length of the plaintext.

Given:
Plaintext: "EXAMPLE"
Keyword: "DATASTRUCTURE"

Step 1: Convert each letter to its corresponding position in the alphabet:
E = 5, X = 24, A = 1, M = 13, P = 16, L = 12, E = 5
D = 4, A = 1, T = 20, A = 1, S = 19, T = 20, R = 18

Step 2: Add the positions of the plaintext and keyword letters:
(5 + 4), (24 + 1), (1 + 20), (13 + 1), (16 + 19), (12 + 20), (5 + 18)
= 9, 25, 21, 14, 35, 32, 23

Step 3: If the sum exceeds 26, subtract 26 to get the cipher position:
9, 25, 21, 14, 35 - 26 = 9, 32 - 26 = 6, 23

Step 4: Convert these positions back to letters:
9 = I, 25 = Y, 21 = U, 14 = N, 9 = I, 6 = F, 23 = W

Ciphered Text:
The final ciphered text is "IYUNIFW".

Conclusion:
The correct answer corresponds to the following option:
Option A: IYUNIFW