encrypt_file.py

from cryptography.fernet import Fernet
import paramparse

def write_key():
    """
    Generates a key and save it into a file
    """
    key = Fernet.generate_key()
    with open("key.key", "wb") as key_file:
        key_file.write(key)

def load_key():
    """
    Loads the key from the current directory named `key.key`
    """
    return open("key.key", "rb").read()

def encrypt(filename, key):
    """
    Given a filename (str) and key (bytes), it encrypts the file and write it
    """
    f = Fernet(key)

    with open(filename, "rb") as file:
        # read all file data
        file_data = file.read()

    # encrypt data
    encrypted_data = f.encrypt(file_data)

    # write the encrypted file
    with open(filename + '.cry', "wb") as file:
        file.write(encrypted_data)


def decrypt(filename, key):
    """
    Given a filename (str) and key (bytes), it decrypts the file and write it
    """
    f = Fernet(key)
    with open(filename, "rb") as file:
        # read the encrypted data
        encrypted_data = file.read()
    # decrypt data
    decrypted_data = f.decrypt(encrypted_data)
    # write the original file
    with open(filename, "wb") as file:
        file.write(decrypted_data)

def main():
    # # load the previously generated key
    # key = load_key()
    #
    # message = "some secret message".encode()
    #
    # # initialize the Fernet class
    # f = Fernet(key)
    #
    # # encrypt the message
    # encrypted = f.encrypt(message)
    #
    # decrypted_encrypted = f.decrypt(encrypted)
    # print(decrypted_encrypted)

    write_key()
    # load the key
    key = load_key()
    # file name
    file = "Z:\\Lectures\\temp.txt"

    # encrypt it
    encrypt(file, key)

if __name__ == '__main__':
    main()