Question 3 [8 marks] It is important that the e-mail messages can only be read by their intended recipient This can be achieved by encrypting (encoding) the original message, so that the text does not make sense unless the reader can decrypt (or decode). A simple encoding scheme can be constructed as follows, using a series of functions (ie. composite functions): 1) Each letter of the alphabet (only consider lower-case letters here) is mapped to a number (see Table 1 Table : Map of the lowercase letters to a specific character value. Lower-case letter a bcd eg hk m Caractervalue(? 10 1 2 3 4 5 6 7 8 9 10 11 12 n oPs uv Wxy z Character value (c) 13 14 15 16 17 18 19 20 21 22 23 24 25 e letter 2 We define the encryption function F as where c, is the character value from Table1, and Fc) is the modified character value. Note: The function Fis used to encrypt the message. s constructed using the transformed character Finally, the values produced by F) as per the mapping defined in Table 1. new Encoding example A message, such asz is transformed as follows using this scheme 1) The message is mapped to the character locations as per Table 1 usqmaths-20 18161201971s. 2) The character positions are transformed using F. Hence, these become: F(20)(320)mod26-13 F18)(3 185)mod267 F(16) - (3x 16 + 5)mod26-1 F(O)(305)mod26-5 F(19) - (3 ? 19 + 5)lnod26 . 10 F(7)3205)mod26 0 F18)3 185)mod267 3) Using the new positions the message becomes: 1371155 100nhbptkah Note: This table defines a functios