Answer to Question #179894 in Python for chris cameron

Question

Write a python program to achieve Advanced Encryption Standard 128 bit key length encoding and decoding of text.

Program should be algorithm based rather than using any library function. Write both ENCODING and DECODING.  

Input text

“To be, or not to be, that is the question: Whether 'tis nobler in the mind to suffer

The slings and arrows of outrageous fortune,

Or to take arms against a sea of troubles

And by opposing end them. To die—to sleep,

No more; and by a sleep to say we end

The heart-ache and the thousand natural shocks

That flesh is heir to: 'tis a consummation

Devoutly to be wish'd. To die, to sleep;

To sleep, perchance to dream—ay, there's the rub:

For in that sleep of death what dreams may come,

When we have shuffled off this mortal coil,

Must give us pause—there's the respect

That makes calamity of so long life.

When he himself might his quietus make

With this regard their currents turn awry

And lose the name of action.”

Answer 1

For this first we need to install Cryptography library using the pip command as follows:

pip install cryptography

Now, the code is as follows:

Note- keep input text in file 'ínputFile.txt'

from cryptography.fernet import Fernet
# Use Fernet to generate the key file.
key = Fernet.generate_key() # Store the file to disk to be accessed for en/de:crypting later.
with open('secret.key', 'wb') as new_key_file:
    new_key_file.write(key)

#-------------------Encryption-----------------------
file = open('inputFile.txt')
msg = file.read()
# (Refer to Encoding types above).
msg = msg.encode()
#encrypt the message
# Instantiate the object with your key.
f = Fernet(key)# Pass your bytes type message into encrypt.
ciphertext = f.encrypt(msg)
print('\nencrypted message is as following: \n')
print(ciphertext)

#-----------------Decryption-------------------------------#
# Load the private key from a file.
with open('secret.key', 'rb') as my_private_key:
    key = my_private_key.read()# Instantiate Fernet on the recip system.
f = Fernet(key)# Decrypt the message.
cleartext = f.decrypt(ciphertext)# Decode the bytes back into a string.
decrypted_message = cleartext.decode()

print("\nmassage after decryption:\n")
print(decrypted_message)

output: