Two pieces of ciphertexts are given below. The first one is encrypted using Vigenere cipher, whereas

the second one is encrypted using Caesar cipher. Using CrypTool software, perform a ciphertext only

attack on both pieces of ciphertext.

a)

Explain the cryptanalytic method you used to break the code and mention the results of the

cryptanalysis you made to guess the key

b)

Find the encryption key

c) Find the corresponding plaintext

Vigenere Cipher

dithcmkl xitulrzfxw klamtnwpp vyzfygi dbci kulr r clvkvnycnc ectzvzgsq fe avfgzgfy.elvl lpjb cihhtvv gsek

clvkvnmgnyxj op me czwjrdwzby sw fzqv fpgire meszvdnemfa, hlzps vrvdij dfijgtsef Iffhe xyr nvvnemfa,

omjgcmshemfa, Iru ccskrnxzby sw gsek fpgire meszvdnemfa. elvep ecfz qrl mi r eppznygv by

gfzxyevnekvzrj ccskbnscf hlffp fvulzzbc qrl nsdcwmtnei kup xrfv sw qpzvyztzar xyr dithcmkl xitulrzfx. jfe

pbrzapv, vq xyr avfcpv whygkvzrzar sw gsi jrnyivec drnlratwd epulvcij fpxkvyk kvxi cvxmkf zr kup xinywzg

emdr zj r zpwjnri wezq jryhve es irnizipv, kupr raj tibestbw si apxnbco kulx zaevfqfgvf geivlfcr,

frgephzpeesyp hvylcj zlc iryhve dytu emdr wmdvew drlrzarpvfd.

Caesar Cipher

qeb jlob zofqfzxi x zljmlkbkq lo pbosfzb, qeb efdebo fp qeb ibsbi lc xsxfixyfifqv obnrfoba. zlkpfabo x

pvpqbj qexq molsfabp xrqebkqfzxqflk pbosfzbp clo zofqfzxi pvpqbjp, xmmifzxqflkp, xka absfzbp. xk

fkqboormqflk lc pbosfzb obpriqp fk qeb fkxyfifqv clo zrpqljbop ql xzzbpp zljmrqfkd obplrozbp xka pqxcc

ql xzzbpp qeb obplrozbp qebv kbba ql mbocloj zofqfzxi qxphp. qeb ilpp lc qeb pbosfzb qoxkpixqbp fkql x

ixodb cfkxkzfxi ilpp fk ilpq bjmilvbb molarzqfsfqv xka mlqbkqfxi zrpq|jbo ilpp.