Question

Match List - I with List - II. 

List - I		List - II
A.	Caesar Cipher	I.	Substitution cipher using \(5 \times 5\) matrix
B.	Playfair Cipher	II.	Polyalphabetic cipher using matrix multiplication
C.	Hill Cipher	III.	Monoalphabetic cipher using fixed shift
D.	Vigenère Cipher	IV.	Polyalphabetic cipher using keyword repetition

Choose the correct answer from the options given below:

• A. A-III, B-I, C-IV, D-II
• B. A-III, B-I, C-II, D-IV
• C. A-II, B-III, C-I, D-IV
• D. A-III, B-IV, C-I, D-II

Hint:

Caesar = Fixed Shift. Playfair = $5 \times 5$ Box. Hill = Matrix Math. Vigenere = Key Word repeat.

Answer 1

The Correct Option is B

Concept:
• Cryptography techniques are classified based on how characters are substituted.
• Monoalphabetic: One fixed substitution for each character throughout the message.
• Polyalphabetic: Substitutions change based on the position of the character and a key.

Step 1: Match A with III (Caesar Cipher)
The Caesar cipher is the most basic "monoalphabetic" cipher where each letter is shifted by a "fixed" number of positions (e.g., \(n=3\)). So, A matches with III.

Step 2: Match B with I (Playfair Cipher)
The Playfair cipher is a manual symmetric encryption technique that uses a "\(5 \times 5\) matrix" of letters to encrypt pairs of letters (digrams). So, B matches with I.

Step 3: Match C with II (Hill Cipher)
The Hill cipher is a "polyalphabetic" substitution cipher based on linear algebra. It uses "matrix multiplication" to encrypt blocks of text. So, C matches with II.

Step 4: Match D with IV (Vigenere Cipher)
The Vigenere cipher uses a keyword that is repeated across the plaintext. The "keyboard repetition" refers to the periodic shift change based on the keyword letters. So, D matches with IV.