1.

(a). Using the a¢ ne function Ee(x) = 5x + 8mod26 encipher the plain text "its cool". (b). Determine the corresponding decryption function.

2.

(a). Using the Hill method with matrix M=3 6 1 5mod 26 encryptthe text "movies". (b). Using the inverse matrix M1; apply the inverse transformation to the encrypted message and hence show that it is "movies" as expected. State clearly what is required for M1 to exist.

3.

Theencryptedmessage"eznwxzpwlprzdcmugablxyqlhvjvpkgftkkwchru fmrycgvqduswkuevvkcviiyjkvtzwrplbppzvigfhrviuvvgtiramtctebvgqatzxygdp ymfwapskftqioqjcztpqgnmblrkgldugfoxjaiiutpykvkvilkvtapyilumsmsiumrbvvg vrycgvqdu" was obtained using the Vigenere method. Determine the original plain text which should be "readable" and make sense. You may use Maple providing key steps are clearly explained. Copy and paste the given encripted message directly into your Maple worksheet.

2018-03-05
Maths