Question

Which of the following cipher uses a key book or a key text instead of a keyword?

(a) vigenere cipher

(b) autokey cipher

(c) running key cipher

(d) affine cipher

The question was posed to me in final exam.

The query is from Cryptography in chapter Cryptography of Data Structures & Algorithms II

Answer 1

The correct choice is (c) running key cipher

The explanation is: Running key cipher is a poly alphabetic cipher. It uses a key book or key text instead of a keyword which is agreed by both parties before encryption takes place.