Question

Running key cipher is an example of _______________

(a) mono-alphabetic cipher

(b) poly-alphabetic cipher

(c) transposition cipher

(d) additive cipher

This question was posed to me by my college director while I was bunking the class.

My enquiry is from Cryptography topic in division Cryptography of Data Structures & Algorithms II

Answer 1

Correct choice is (b) poly-alphabetic cipher

The explanation is: Running key 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.