Objectives:

Familiarize the student with:

• Practice Python tools to encrypt and decrypt files;
• Account for missing files;

Task:

Consider the Python .py file(s) provided with this assignment on Blackboard and modify the code to meet the following requirements:

• Complete the main function that will run whenever the module is called;
• The main function should interact with the user and allow the user to specify whether he or she want to encrypt or decrypt;
• The user should be allowed to choose between 1) the insecure mode where the encryption key file is saved for usage in decryption or 2) a more secure way where the key is generated whenever it is used through a passphrase;
• The user should be allowed to input the file to encrypt or decrypt;
• When a user input the file to encrypt, the program should identify the file extension explicitly. That same extension should be added to the encrypted file and the decrypted file.
• The program should be able to run from the command line interface and the python shell. Demonstrate both and submit screenshots of your demonstration.

source codes are

encrpt_dcrpt_sample

from cryptography.fernet import Fernet

import os.path, sys

def key_gene():

#create a key

my_Key = Fernet.generate_key()

#write the key to a file

with open("my_kkey.key", "wb") as kf:

kf.write(my_Key)

#print the size of the key file

print(f"Size of the key file is {os.path.getsize('my_kkey.key')} Bytes")

return(my_Key)

def encryption(f2encrypt):

#get the key from the key_gene function

key = key_gene()

fu = Fernet(key) #tool with the key

#get the file

with open(f2encrypt, 'rb') as file:

file_data = file.read()

#encrypt the file

encrypted_data = fu.encrypt(file_data)

with open('new_file.txt', 'wb') as f:

f.write(encrypted_data)

#print file sizes

print(f"Size of the file to encrypt is {os.path.getsize(f2encrypt)} Bytes")

print(f"Size of the encrypted file is {os.path.getsize('new_file.txt')} Bytes")

#decrypt

def decryption(file2decrypt, key_file):

print('Trying to decrypt!')

#read the key file as a binary and buld the tool with the key

key = ''

with open(key_file, 'rb') as f:

key = f.read()

fu = Fernet(key)

#open the file to decrypt as a byte Python object

data2decrypt = ''

with open(file2decrypt, 'rb') as f:

data2decrypt = f.read()

#decryption

decrypted_data = fu.decrypt(data2decrypt)

#Save the decrypted data to a file named 'decrypted_file'

with open('decrypted_file.txt', 'wb') as f:

f.write(decrypted_data)

if __name__ == '__main__':

encryption('file1.txt') #I added an option to select how the encryption will be done

decryption('new_file.txt', 'my_kkey.key')

encrpt_dycrpt_password

import from cryptography.fernet import Fernet

import sys

#####For password-based key

import base64

from cryptography.hazmat.backends import default_backend

from cryptography.hazmat.primitives import hashes

from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC

def key_gene_from_password():

password = input("Input the encryption password: ")

password = password.encode() # Convert to type bytes

salt = b'salt_'

kdf = PBKDF2HMAC(

algorithm=hashes.SHA256(),

length=32,

salt=salt,

iterations=100000,

backend=default_backend()

)

keyy = base64.urlsafe_b64encode(kdf.derive(password)) # Can only use kdf once

print("Key generated")

return(keyy)

def encryption(f2encrypt):

#get the key from the key_gene function

key = key_gene_from_password()

fu = Fernet(key) #tool with the key

#get the file

with open(f2encrypt, 'rb') as file:

file_data = file.read()

#encrypt the file

encrypted_data = fu.encrypt(file_data)

with open('new_file11.txt', 'wb') as f:

f.write(encrypted_data)

#print file sizes

# print(f"Size of the file to encrypt is {os.path.getsize(f2encrypt)} Bytes")

# print(f"Size of the encrypted file is {os.path.getsize('new_file.txt')} Bytes")

#decrypt

def decryption(file2decrypt):

print('Trying to decrypt!')

try:

#Obtain key

key = key_gene_from_password()

fu = Fernet(key)

#open the file to decrypt as a byte Python object

data2decrypt = ''

with open(file2decrypt, 'rb') as f:

data2decrypt = f.read()

#decryption

decrypted_data = fu.decrypt(data2decrypt)

#Save the decrypted data to a file named 'decrypted_file'

with open('decrypted_file11.txt', 'wb') as f:

f.write(decrypted_data)

except:

print("Your password may be wrong!")

if __name__ == '__main__':

# encryption('file11.txt') #I added an option to select how the encryption will be done

decryption('new_file11.txt')