$**$Cryptography$**$

The question must be solved by XOR:

Question$1$:

$($a$)$: $(1)$: $($a$)$Using the Vernam cipher, encrypt and decrypt the word "HELLO" using the Key value $"$DGHBC$".$

$(2)$: Consider Caesar cipher to perform encryption and decryption using the key value k$=3.$ The plaintext is "FIVE MINUTES ENGINEERING".

$(3)$: Encrypt the message "HELLO WORLD" using the Hill cipher with the key $\left[\begin{array}{cccc}2& 1& ?& ?\\ 3& 4& ?& ?\\ ?& ?& ?& ?\\ ?& ?& ?& ?\end{array}\right].$

$($i$).$ Show your calculations and the result.

$($ii$).$ Show the calculations for the corresponding decryption of the ciphertext to recover the original plaintext.