17.

(i) Using Z27 for multiplicative Caesar ciphers, write down the eighteen possible pairs (e, d) with 1 e < 27, 1 d < 27 where e is an encrypting multiplier and d is the corresponding decrypting multiplier.

(ii) Design a Vigen`ere cryptosystem using multiplicative Caesar ciphers in Z27, choosing an easily remembered piece of English text of at least six letters as the encrypting key text . (try to find longest english word)