Let the alphabet of definition be A = {1,2,3,4,5}; both the plaintext space M and the ciphertext space C consist of strings of length 6 over this alphabet. a) Define a substitution cipher S on A. Draw a functional diagram of your encryption function, and use S to encrypt the plaintext 132354. [7 marks] b) Define a transposition cipher T on M and use T to encrypt the plaintext 324132. [5 marks] c) Use your answers to parts a) and b) to define the product cipher P = S T and use P to encode the plaintext 351324. [4 marks] d) Construct P1, the inverse of the product cipher you defined in part c), and use it to decrypt the ciphertext 315442.