Engineering Questions with Answers - Multiple Choice Questions

# Hill Cipher Multiple Choice MCQ

1 - Question

Hill cipher requires prerequisite knowledge of?
a) integration
b) differentiation
c) matrix algebra
d) differential equation

Explanation: Hill cipher uses matrix multiplication in order to encrypt the given plain text. So it requires prerequisite knowledge of matrix algebra.

2 - Question

Hill cipher is an example of ____________
a) mono-alphabetic cipher
b) substitution cipher
c) transposition cipher

Explanation: Hill cipher is a substitution cipher. It falls under the category of poly alphabetic cipher as it uses multiple substitutions at different positions in order to cipher the plain text.

3 - Question

Encryption in hill cipher is done using ______________
a) matrix multiplication
b) a 5×5 table
c) vigenere table
d) matrix inversion

Explanation: Encryption of plain text in playfair cipher is done using matrix multiplication. Then modulo 26 of the resulting matrix is taken so as to get the ciphered text.

4 - Question

What is poly graphic substitution cipher?
a) a substitution based cipher which uses multiple substitutions at different positions
b) a substitution based cipher which uses fixed substitution over entire plain text
c) a substitution based cipher in which substitution is performed over a block of letters
d) a transposition based cipher which uses fixed substitution over entire plain text

Explanation: Poly graphic cipher is a type of substitution cipher in which substitution is performed over a block of letters. Hill cipher is an example of poly graphic cipher.

5 - Question

Which of the following was the first poly graphic cipher to be able to operate on more than 3 letters at once?
a) autokey cipher
b) hill cipher
d) playfair cipher

Explanation: Poly graphic cipher is a type of substitution cipher in which substitution is performed over a block of letters. Hill cipher was the first poly graphic cipher to be able to operate on more than 3 letters at once.

6 - Question

Which of the following is hardest to break using frequency analysis?
a) Vigenere cipher
b) Hill cipher
c) Caesar cipher
d) Affine cipher

Explanation: Out of the given options hill cipher is the hardest cipher to break using frequency analysis. Although it is quite vulnerable to other forms of attack.

7 - Question

Hill cipher is harder to crack than playfair cipher.
a) True
b) False

Explanation: Both hill cipher and playfair cipher are less vulnerable to frequency analysis. But hill cipher is quite vulnerable to other forms of attack and thus less secure than playfair cipher.

8 - Question

What will be the plain text corresponding to cipher text “YGQ“ if hill cipher is used with keyword as “GYBNQKURP”?
a) SECRET
b) WORLD
c) DOLLAR
d) HELLO

Explanation: To decrypt the message we follow the reverse procedure. We first find the inverse of the keyword matrix then multiply it with cipher matrix.

9 - Question

What will be the size of a key matrix if the plain text is “SECRET”?
a) 1×6
b) 5×1
c) 6×1
d) 6×6

Explanation: Hill cipher uses a n x n matrix in order to cipher the plain text. In this case n=6 so a 6×6 matrix will be used.

10 - Question

A key matrix used for encryption in hill cipher must be?
a) invertible matrix
b) non invertible matrix
c) square matrix
d) rectangular matrix

Explanation: A key matrix used for encryption in hill cipher must be invertible matrix. Otherwise it will be impossible to decipher the message.

11 - Question

What will be the ciphered text if the plain text “SAN” is encrypted using hill cipher with keyword as “GYBNQKURP”?
a) RAJ
b) JAR
c) ARJ
d) AJR