Note: research on Python how to convert this hexadecimal string to a binary string or binary value. Start with small values, then test the $8-$byte $(64-$bit$)$ key with plaintext.

For simplicity, let$$s test it locally first $($i$.$e$.,$ you can call the functions at the bottom of your file, or in a separate main file$).$ The output should be the $$intermediate ciphertext$$ that we call state. To check if you$$re doing this addRoundKey function correctly, here is the ciphertext C$1$ that you should get with the plaintext and key given above.

C$1=($you should get this: $0$x$2997971$cabf$44637)$

Test the decryption as well $($it should be the same operation$).$ Check if you can recover the plaintext

Task $2$: Four$-$bit S$-$Box

This is the S$-$box layer defined in the PRESENT algorithm.

For the encryption. every letter x is a $4-$bit hexadecimal value in Table $2$ which is replaced with the value S$($x$).$