Alice and Bod have decided to use a symmetric encryption algorithm. They have some

assumptions about their messages:

$-$ Messages only contain capital letters $($i$.$e$.$ A to Z$)$

$-$ The length of their shared key must be greater than or equal to the length of the plaintext

$-$ They assign each letter a number as follows: $($A$,0),($B$,1),($C$,2),($D$,3),...,($Z$,25)$

Their algorithm combines the key and the message using modular addition. The numerical values

of corresponding message and key letters are added together, modulo $26.$ For example, if the plain

text is $$HELLO$$ and the key is $$SECRET$$ then the encrypted message is calculated as following:

Since the length of the plaintext is $5,$ we just need the first $5$ letters of the key $($i$.$e$.$SECRE$),$ then

for each letter, we should add corresponding letters in both the plaintext and the key modulo $26.$

Plaintext: H $(7)$ E $(4)$ L $(11)$ L $(11)$ O $(14)$

Key: S $(18)$ E $(4)$ C $(2)$ R $(17)$ E$(4)$

Cipher: Z $(25)$ I $(8)$ N$(13)$ C$(2)$ S $(18)$

a$)$ Write a program in Python, C$/$C$++$ or JavaScript to take both the plaintext and the key as

its input, then print out the cipher. Assume the plaintext is your name, for the

key$=$THISISANEXAMPLEKEYINCOMPUTERSECURITYEXAM$$ what is the

output?