Question

What is the significance of indicator block in running key cipher?

(a) it helps in encryption

(b) it strengthens the cipher

(c) it gives information regarding the book/text from where the key is taken

(d) it makes encryption easy

I have been asked this question by my college director while I was bunking the class.

My question is taken from Cryptography topic in portion Cryptography of Data Structures & Algorithms II

Answer 1

The correct choice is (c) it gives information regarding the book/text from where the key is taken

Best explanation: The purpose of having an indicator block in running key cipher is to give information to the receiver about the source of a key being used. It is usually included in the second last block of the message.