What will be the plain text corresponding to cipher text "IWRWHS" if running key cipher is used with keyword as "DATASTRUCTURE"?

Solution (By Examveda Team)

Running Key Cipher is a polyalphabetic substitution cipher where the ciphered text is combined with a keyword to retrieve the plaintext. The keyword is often as long as or longer than the ciphered text.

Given:
Ciphered Text: "IWRWHS"
Keyword: "DATASTRUCTURE"

Step 1: Convert each letter of the ciphered text and keyword to its corresponding position in the alphabet:
I = 9, W = 23, R = 18, W = 23, H = 8, S = 19
D = 4, A = 1, T = 20, A = 1, S = 19, T = 20

Step 2: Subtract the position of the keyword letter from the ciphered text letter position:
(9 - 4), (23 - 1), (18 - 20), (23 - 1), (8 - 19), (19 - 20)
= 5, 22, -2, 22, -11, -1

Step 3: If the result is negative, add 26 to get the position within the alphabet:
5, 22, 24 (because -2 + 26 = 24), 22, 15 (because -11 + 26 = 15), 25 (because -1 + 26 = 25)

Step 4: Convert these positions back to letters:
5 = E, 22 = V, 24 = Y, 22 = V, 15 = O, 25 = Y

Plain Text:
The final plain text is "EVYVOY".

Conclusion:
The newly created option that corresponds to the plain text is:
Option A: EVYVOY