Write a script in Python to implement the AES algorithm. The official documentat

Question

Write a script in Python to implement the AES algorithm. The official documentation of AES can be found at: http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf. Your script must comply to the following requirements:

1. It should read input from a text file plaintext.txt, write the encrypted output in HEX form to another text file encryptedtext.txt and subsequently decrypt encryptedtext.txt and save the decrypted output to decryptedtext.txt.

2. The file plaintext.txt

should contain the following text. In your output, you are supposed to

encrypt and than decrypt the following text:

“This is an unusual paragraph. I’m curious how quickly you can find out what is so unusual

about it? It looks so plain you would think nothing was wrong with it! In fact, nothing is

wrong with it! It is unusual though. Study it, and think about it, but you still may not

find anything odd. But if you work at it a bit, you might find out! Try to do so without

any coaching! You most probably won’t, at first, find anything particularly odd or unusual

or in any way dissimilar to any ordinary composition. That is not at all surprising, for it is

no strain to accomplish in so short a paragraph a stunt similar to that which an author did

throughout all of his book, without spoiling a good writing job, and it was no small book at

that.”

3. Use the following as your key:

lukeimyourf ather

Explanation / Answer

key=lukeimyourf ather

fi have created two functions 1)encrypt 2)decrypt.

i am using plaintext file to read data and then i am sending msg for encryption.

After encryption i store data in encrypt.txt , then i read that file and decrypt data and stores it in decrypt.txt.

//////////////////////////////////////////////////

def decrypt(self):

f=fopen(encryptedtxt.txt,”r”)

F1=f.readlines();

For x in f1:

Msg=msg+x;

enc = base64.b64decode(msg)

cipher = AES.new(self.key, AES.MODE_CBC, iv())

dec = cipher.decrypt(msg)

f=fopen(decryptedtxt.txt,”a”)

f.writelines(msg);

f.close()

//////////////////////////////

def encrypt(key,msg):

iv = Random.new().read(BS)

cipher = AES.new(key, AES.MODE_CFB, iv, segment_size=AES.block_size * 8)

encrypted_msg = cipher.encrypt(pad(str(msg)))

f=fopen(encryptedtxt.txt,”a”)

f.writelines(encrypted_msg);

f.close()

////////////////////////////////////////

F=open(“plaintext.txt”,”r”);

F1=f.readlines();

For x in f1:

msg=msg+x;

f.close()

encrypt(keyVal, msg)

decrypt()

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