Question

Which of the following cipher is a special case of affine cipher?

(a) Vigenere cipher

(b) Autokey cipher

(c) Atbash cipher

(d) Hill cipher

I have been asked this question in an international level competition.

My question is based upon Cryptography in section Cryptography of Data Structures & Algorithms II

Answer 1

Correct option is (c) Atbash cipher

Easiest 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.