The Vigenère Cipher is an encryption algorithm that combines the
use of a keyword with the message to be encrypted. A tableau is
provided that shows an encrypted character for each combination of
characters in the message and the keyword.
Using the Vigenère Tableau encryption scheme with a keyword of
KEYWORD, encrypt the following message:
IS INFORMATION SECURITY ESSENTIAL
After encrypting the message, decrypt the following message,
using KEYWORD as the keyword:
YRJUW WWRIG JTFUW ERECE LCMKL CIWKR R
For...