Q$1$: A disadvantage of the general monoalphabetic cipher is that both sender and receiver must

commit the permuted cipher sequence to memory. A common technique for avoiding this is to

use a keyword from which the cipher sequence can be generated. For example, using the

keyword CIPHER, write out the keyword followed by unused letters in normal order and match

this against the plaintext letters:

plain: abcdefghijklmnopqrstuvwxyz

cipher: CIPHER A B D F GJKLMNOQS TUVWXYZ

If it is felt that this process does not produce sufficient mixing, write the remaining letters on

successive lines and then generate the sequence by reading down the columns:

C I P HER

A B D F GJ

KLMNOQ

S T UVW X

Y Z

This yields the sequence:

CAKS YIBLTZPDMUHFNVEGOWRJQX

Use this technique to determine the KEYWORD in the following plaintext and ciphertext?

Plaintext: $"$it was disclosed yesterday that several informal but direct contacts have been made

with political representatives of the viet cong in Moscow"

Ciphertext: "UZQSOVUOHXMOPVGPOZPEVSGZWSZOPFPESXUDBMETSXAIZ

VUEPHZHMDZSHZOWSFPAPPDTSVPQUZWYMXUZUHSX

EPYEPOPDZSZUFPOMBZWPFUPZHMDJUDTMOHMQ"