cipherize.py

"""
Encrypts or Decrypts messages. For encryption:

    python cipherize.py --message=test --action=encrypt

    or

    python3 cipherize.py --filepath /path/to/file --action encrypt

Decryption:

    python cipherize.py --message=gAAAAABhr31eV25KDnD-X1fI8S2gE4i5ynW3aJl-JYzmT2U2Sm_Gz5DFzZEDbREShM1PqJDZafxEw6ex3cvNNMdKWPmJj2irgQ== --action=decrypt

    or

    python3 cipherize.py --filepath /path/to/file --action decrypt

The password is a master key.
"""


import argparse
import base64
import getpass
import cryptography.fernet as fernet


parser = argparse.ArgumentParser()
parser.add_argument(
    '--message',
    help=('Message to decrypt or encrypt, according to chosen action input'),
    type=str,
    required=False
)
parser.add_argument(
    '--action',
    help=('Either "encrypt" or "decrypt"'),
    choices=['encrypt', 'decrypt'],
    type=str,
    required=True
)
parser.add_argument(
    '--filepath',
    help=('If defined, then reads the content from the specified path.'),
    default='',
    type=str,
    required=False
)


def key_is_valid(key: str) -> bool:
    if not key:
        return False
    if len(key) != 32:
        return False
    return True

if __name__ == '__main__':
    args = parser.parse_args()
    message, action, filepath = args.message, args.action, args.filepath
    if filepath:
        if message:
            raise RuntimeError('If `filepath` is defined then `message` should be None.')
        message = open(filepath).read().encode()
    else:
        message = message.encode()
    key = getpass.getpass()
    if action == 'encrypt':
        confirm = getpass.getpass('Confirm Password:')
        if key != confirm:
            raise RuntimeError('Password mismatch!')
    if not key_is_valid(key):
        raise RuntimeError(
            'Please choose a valid input key. It must contain 32 url-valid characters.')
    key = base64.b64encode(key.encode())
    ferneter = fernet.Fernet(key)
    if action == 'encrypt':
        print('Encrypted message:\n', ferneter.encrypt(message), '\n')
    elif action == 'decrypt':
        print('Decrypted message:\n', ferneter.decrypt(message), '\n')