# Crosscompute

secret_key = 'secret key'
target_text_path= 'm.txt'
encrypt_or_decrypt_select = '''
    encrypt
    
    encrypt
    decrypt'''
target_folder = '.'

encrypt_or_decrypt = [x.strip() for x in 
    encrypt_or_decrypt_select.split('\n') if x.strip()][0] 

l = len(secret_key)
filler = '@'
accepted_lengths = sorted([16, 24, 32])
for byte_length in accepted_lengths:
    if l < byte_length:
        secret_key += (filler * (byte_length - l))
        break
else:
    secret_key = secret_key[:32]

from Crypto.Cipher import AES

def encrypt(k, m):
    aes = AES.new(k, AES.MODE_CFB, 'This is an IV456')
    return aes.encrypt(m)


def decrypt(k, ciphertext):
    aes = AES.new(k, AES.MODE_CFB, 'This is an IV456')
    return aes.decrypt(ciphertext)

from ast import literal_eval


with open(target_text_path, 'r', encoding='utf-8') as f:
    if encrypt_or_decrypt == 'decrypt':
        source = f.read()
        target_text = literal_eval("b'{}'".format(source))    
        print('plain text = %s' % decrypt(secret_key, target_text))
    else:
        target_text = f.read()
        print('ciphertext = %s' % encrypt(secret_key, target_text))