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.

• 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')

  #