Suppose there is a symmetric encryption scheme, CS, that on input an 8-bit message, P, and a key, K, procedures a ciphertext, C.K is a positive integer. CS performs a right circular shift on P based on K. For example, if P is 01011011 and K is 3,C is 01101011. You are given a string, S, which is having a value of "POLYU". Perform the following tasks: a) Write down the binary form of S, based on 8-bit ASCII code representation. [4 marks] b) Encrypt S using CS. The mode of operation is ECB. K is 4 . Represent C in binary representation. [6 marks] c) Encrypt S using CS. The mode of operation is CBC. K is the last numeric digit of your student ID. Represent C in binary representation. The initialization vector is ' X '. [10 marks]