# Atbash Cipher Multiple Choice Questions and Answers (MCQs)

This set of Data Structures & Algorithms Multiple Choice Questions & Answers (MCQs) focuses on “Atbash Cipher”.

1. Which of the following cipher does not require a key for encrypting plain text?
a) atbash cipher
b) affine cipher
c) playfair cipher
d) vigenere cipher

Explanation: Out of the given options only atbash cipher does not require a key for encryption. Atbash cipher is an example of a substitution cipher.

2. Atbash cipher was originally used for encrypting _____________
a) english alphabet
b) greek alphabet
c) hebrew alphabet
d) hindi alphabet

Explanation: Atbash cipher was originally built to encrypt hebrew alphabet. But it can be used to encrypt any type of alphabets.

3. Which of the following cipher is a special case of affine cipher?
a) Vigenere cipher
b) Autokey cipher
c) Atbash cipher
d) Hill cipher

Explanation: Atbash cipher is a special case of affine cipher. We have to assume a=b=25 as the key in affine cipher to get the same encryption.

4. Choose the weakest cipher from the following?
a) vigenere cipher
b) rail fence cipher
c) hill cipher
d) atbash cipher

Explanation: Atbash cipher is the weakest cipher out of the given options. This is because it is a simple mono alphabetic substitution cipher with almost no security. It can be cracked without even knowing which technique has been used for encryption.

5. Which of the following is a mono alphabetic substitution cipher?
a) vigenere cipher
c) play fair cipher
d) atbash cipher

Explanation: Atbash cipher is the only mono alphabetic substitution cipher out of the given options. All the remaining options fall under the category of poly alphabetic cipher.
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6. Atbash cipher is less secure than affine cipher.
a) True
b) False

Explanation: Affine cipher is more secure as compared to pigpen cipher. Atbash cipher is a special case of affine cipher and can be cracked without even knowing which technique has been used for encryption.

7. Atbash cipher is an example of?
a) Mono alphabetic substitution cipher
b) Transposition cipher
c) Poly alphabetic substitution cipher
d) Geometric substitution cipher

Explanation: Atbash cipher is an example of mono alphabetic substitution cipher. It replaces each alphabet of the plain text with a corresponding letter which we can see in the table below.

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

8. Atbash cipher cannot be cracked until the exact type of encryption of ciphered text is known.
a) True
b) False

Explanation: Atbash cipher is a very weak cipher. It can be easily broken without even knowing the exact technique which has been used for encryption. We can just assume the ciphered text to be a substitution cipher in order to crack it.

9. What will be the ciphered text corresponding to plain text “SECRET” if atbash cipher is used for encryption?
a) VHIXVG
b) HVXIVG
c) HXVIVG
d) VIHXIV

Explanation: Atbash cipher replaces each alphabet of the plain text with a corresponding letter which we can see in the table below.

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

So the ciphered text would be “HVXIVG”.

10. What will be the plain text corresponding to ciphered text “MAO” if atbash cipher is used for encryption?
a) NZL
b) IND
c) AUS
d) ENG

Explanation: Atbash cipher replaces each alphabet of the plain text with a corresponding letter which we can see in the table below.

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

So the plain text would be “NZL”.

11. Which of the following is not true about atbash cipher?
a) it is a mono alphabetic substitution cipher
b) it can only be used to encrypt hebrew alphabet
c) it is a special case of affine cipher
d) it is weaker than playfair cipher

Explanation: Atbash cipher was originally built to encrypt hebrew alphabet. But it can be used to encrypt any type of alphabets.

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