Write a program in C that simulates a Vigenere with Cipher Block Chaining. The program must 1) read in an input file 2) strip off any characters that are not alphabetic letters 3) change upper case letters to lower case 4) encrypts the resulting data using the Vigenere cipher as a block cipher in the Cipher Block Chaining mode of operation. The input plaintext file name, the Vigenere key, and the Initialization Vector will be given to the program as command line arguments.