$1.($a$)$: Using the Vernum cipher, encrypt the word $$Security$$ using the key $$Cry$.$

$($b$)$ Consider Caesar cipher to perform encryption and decryption. The plaintext is

$$Tomorrow is Party$.$

c$)$ Encrypt the message $$meet me at the usual place at ten rather than eight o clock$$

using the Hill cipher with the $.$ Show your calculations and the result

$25$

$2.($a$)$ By using the Vigenere Cipher, perform encryption and decryption. The plaintext is

$$Message cannot break$$ and keyword is $$CIPHER$.$