Question

K2 is derived by left shifting L by 2 bits. What is L defined as?

(a) E(K , 0^b)

(b) E(K , 10*^b)

(c) E(K , 1^b)

(d) E(K , 10*1^b)

I had been asked this question in a national level competition.

This question is from HMAC, DAA and CMAC topic in section Message Authentication Codes, Whirlpool Algorithm and Key Management and Distribution of Cryptograph & Network Security

Answer 1

Correct answer is (a) E(K , 0^b)

To explain: L is defined as encrypting b-bits of 0s with the key K through the same algorithm.