def rand_encrypt(key, secret):
block_size = 16
secret = pad(pad_rand(secret), block_size)
if randint(0, 1):
return encrypt_ECB(key, secret)
else:
return encrypt_CBC(key, secret)
def encrypt_CBC(key, text):
block_size = 16
text_blocks = generate_blocks(pad(text), block_size)
initialisation_vector = b'\x00' * block_size
cipher_blocks = [initialisation_vector]
for i in range(len(text_blocks)):
xor = fixed_xor(cipher_blocks[i], text_blocks[i])
cipher_blocks.append(encrypt_ECB(key, xor, add_padding=False))
return "".join(cipher_blocks[1:])
def encrypt_ECB(key, text, add_padding=True):
cipher = AES.AESCipher(key, AES.MODE_ECB)
if add_padding:
text = pad(text, block_size = len(key))
ciphertext = cipher.encrypt(text)
return ciphertext
