Decrypt DAGFXGXDDAVVVGGVGDGDXX given the key IMAGE

2. a) Decrypt DAGFXGXDDAVVVGGVGDGDXX given the key IMAGE

Write down decryption in CBC mode, and give a detailed explanation why it works

Decrypt 74: 𝐶 ′ = 74 ⋅ 7   ( mod  59 ) = 518   ( mod  59 ) = 46 C ′ =74⋅7 (mod 59)=518 (mod 59)=46 Using the superincreasing sequence ( 2 , 3 , 7 , 15 , 29 ) (2,3,7,15,29): 46 − 29 = 17 17 − 15 = 2 46−29=17 17−15=2

Write a program to perform encryption and decryption using wrapper class Encryption phase with shift n = En (x) = (x+n)mod 26Decryption phase with shift n = Dn (x) = (x-n)mod 26ExamplesText : ABCDEFGHIJKLMNOPQRSTUVWXYZShift : 23Cipher : XYZABCDEFGHIJKLMNOPQRSTUVWinput-output format Text : ATTACKATONCE(input)Shift : 4(input)Cipher : EXXEGOEXSRGI(output)ATTACKATONCE

Use each pair of keys to encrypt and decrypt KIBIRANGO SAUL KKUBO. You may use the provided Ascii Table (Appendix A) to convert your name to binary. If you plain test is not multiple of the block size you can add extra zeros at the end of the plain text to make it multiple of the block size.