In this question we will use a cipher with an encryption function .

C, = (P, + k + j) (mod 26) and the decryption function P, = (C,-k-j) (mod 26) where the subscript J indicates the jth letter in the message (starting at J = 1 for the first letter in the message a) Write a pseudo-code implementation of the encryption function b) Write matlab code(s) to implement both the encryption and decryption functions. Demon- strate that these work as designed by encrypting and decrypting a string of your choosing. c) The ciphertext JZHZEATFPFYQHLXNVNSOMQJCNYAPNZCMPHXSVSGXNPRBXOGVHGMTPYDODRBFHUTMKYXKJKT NJEDXNUUQWDSQCFTIVFVYJBQFHRERDVYOLALKWXRRPTMWKMVNFCRMPTHKJTLZJVWKPFNFKG ZLVLEWHSBDRYYIVVBDCGPHXDXSGXVJXJXZJPJTWUAWLYWEGVP JGJXPZJQRGISFSEWZPMBYC FUSEKSDBWANLKQEBFLRLVYQEXEQ2SH I RYXMQWOGNUTCVTJ 1 AARXTZSCGCRLBI I OBATRJVBW ZIOIBNLFNQDDWAWY is encrypted with this cipher. (You don't need to type this in download the file A13c.mat from canvas and load that into matlab.) Break this encryption using one of the methods we have discussed - give both the plaintext, and the encryption key used. Explain why you chose the method that you did, and SHOW YOUR WORK, ncluding a description of your method, matlab code and/or figures and/or matlab output as needed