$2.$ Block Ciphers $[11$ marks$]2$ You are required to implement two programs in Python aes$-$encrypt.py and aes$-$decrypt.py$.$ Each program takes five arguments: key$=($input file containing $128-$bit key$),$ mode$=$ecb$|$cbc$,$ in$=($input file$),$ out$=($output file$),$ and optional IV$=($file containing IV$).$ For this task, you should use cryptography library in python and not the openssl CLI. For padding, use PKCS$7.2.$a Submit your implementation of aes$-$encrypt.py and aes$-$decrypt.py$.$ You will be marked on the correctness of your solution. If you have used any code from the Internet, specify that in the source files. $[5$ marks$]2.$b Consider the two messages from Mohit to Ian "Mohit$\_$thedrummer:ian rockerrrrrrr: Vangelis $-$ To The Unknown Man" and "Mohit$\_$thedrummer:ian$\_$rockerrrrrrr: Van$-$ gelis $-$ State of Independence". Use aes$-$encrypt with mode$=$ecb and any random key. Provide the hex dump of first $32$ bytes of both ciphertexts. Compare the ciphertexts. Do you see some similarity between the two? Is this a vulnerability and if so$,$ how would you fix it$?[1$ mark$]2.$c Assume that CCS at UoG chooses to use your implementation of aes$-$encrypt and aes$-$decrypt with mode$=$cbc and a counter IV$.$ Does this construction provide confidentiality? Please explain your answer. $[1$ mark$]2.$d Does the construction in $2.$c provide integrity? Please explain your answer $[1$ mark$]2.$e Add Galois Counter Mode $($GCM$)$ support to your aes$-$encrypt.py and aes$-$decrypt.py programs. You may need to pass a parameter for GCM$.$ Pass this as gcm$\_$arg$=($value in ASCII$).$ What is the purpose of this additional parameter? What additional security properties GCM provides? If you have used any code from the Internet, specify that in the source files. $[3$ marks$]$