Object type cannot be passed to C code - virtual environment

Question

I am using Mac Anaconda. And I try to use the AES of Crypto. However, I face a strange problem.

I just want to excute a simple line of code:

 obj = AES.new('This is a key123', AES.MODE_CBC, 'This is an IV456')

if I run the code without the virtual environment as below it is OK.

$ python

Python 3.6.4 |Anaconda, Inc.| (default, Jan 16 2018, 12:04:33) 
[GCC 4.2.1 Compatible Clang 4.0.1 (tags/RELEASE_401/final)] on darwin
Type "help", "copyright", "credits" or "license" for more 
information.
>>> from Crypto.Cipher import AES

>>> obj = AES.new('This is a key123', AES.MODE_CBC, 'This is an IV456')

if I run with the virtual environment "testaes" then I got the error:

(testaes)$ python
Python 3.6.4 |Anaconda, Inc.| (default, Mar 12 2018, 20:05:31) 
[GCC 4.2.1 Compatible Clang 4.0.1 (tags/RELEASE_401/final)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from Crypto.Cipher import AES

>>> obj = AES.new('This is a key123', AES.MODE_CBC, 'This is an IV456')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Applications/anaconda3/envs/testaes/lib/python3.6/site-packages/Crypto/Cipher/AES.py", line 200, in new
return _create_cipher(sys.modules[__name__], key, mode, *args, **kwargs)
File "/Applications/anaconda3/envs/testaes/lib/python3.6/site-packages/Crypto/Cipher/__init__.py", line 55, in _create_cipher
return modes[mode](factory, **kwargs)
File "/Applications/anaconda3/envs/testaes/lib/python3.6/site-packages/Crypto/Cipher/_mode_cbc.py", line 234, in _create_cbc_cipher
cipher_state = factory._create_base_cipher(kwargs)
File "/Applications/anaconda3/envs/testaes/lib/python3.6/site-packages/Crypto/Cipher/AES.py", line 100, in _create_base_cipher
result = start_operation(c_uint8_ptr(key),
File "/Applications/anaconda3/envs/testaes/lib/python3.6/site-packages/Crypto/Util/_raw_api.py", line 109, in c_uint8_ptr
raise TypeError("Object type %s cannot be passed to C code" % type(data))
TypeError: Object type <class 'str'> cannot be passed to C code

You can see that at both time I use the the same Anaconda Python 3.6.4 and GCC4.2.1. How to solve this?

I think you should look to the last line of the traceback. See if encoding your string as bytes work. — chidimo, May 12 '18 at 04:38

score 55 · Accepted Answer · edited Mar 08 '21 at 00:22

55

In Python 3, encode it into a bytearray:

obj = AES.new('This is a key123'.encode("utf8"), AES.MODE_CBC, 'This is an IV456'.encode("utf8"))

If you store these in variables and want to use them as (Python) strings again, just use:

key_as_bytearray.decode("utf8")

Check out this answer for further information.

edited Mar 08 '21 at 00:22

bad_coder

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answered May 12 '18 at 04:56

Arthur Dent

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3

If this is indeed the problem `b"This is a key123"` without any encoding step would work as well. – tdelaney May 12 '18 at 05:06
Thank you. It solves this problem. I did try encode("utf8) with the key, but I did not encode the IV. – geen Frog May 13 '18 at 01:21
@geenFrog if it's just ascii text then `b"myIV"` will work fine, this is just in case you use other chars/encoding – Arthur Dent May 13 '18 at 01:42

score 2 · Answer 2 · answered Aug 07 '22 at 16:36

from Crypto.Cipher import AES
import base64

def encrypt(text):  
    private_key = "xxx".encode('utf-8')   
    iv = "yyy".encode('utf-8')
    cipher = AES.new(private_key, AES.MODE_CBC, iv)

    pad = lambda s: s + (16 - len(s) % 16) * chr(16 - len(s) % 16)
    encrypted =  base64.b64encode( cipher.encrypt(pad(text)))
    return encrypted.decode("utf-8")

This was working fine in Google Collab but It was not showing this above error in Python3 Terminal in Linux. So What I did is -

from Crypto.Cipher import AES
from base64 import b64encode
from Crypto.Util.Padding import pad, unpad

def encrypt(text):
    private_key = bytes("xxx", 'utf-8')
    iv = bytes("yyy", 'utf-8')
    cipher = AES.new(private_key, AES.MODE_CBC, iv)

    encrypted = cipher.encrypt(pad(text.encode("UTF-8"), AES.block_size))
    return b64encode(encrypted).decode('utf-8')

score -1 · Answer 3 · edited Apr 04 '22 at 08:49

-1

Just encode the key and you will get no error:

from Crypto.Cipher import AES
import base64

key = ''

cipher_text = ''
cipher_text = base64.b64decode(cipher_text)


decipher = AES.new(key.encode(), AES.MODE_ECB)

print(decipher.decrypt(cipher_text))

edited Apr 04 '22 at 08:49

vvvvv

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answered Apr 01 '22 at 13:02

iqbal

67
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score -10 · Answer 4 · answered May 14 '20 at 11:41

-10

Python has package named pycryptodome which causes this error.just uninstall the package

sudo pip3 uninstall pycryptodome

answered May 14 '20 at 11:41

Saurabh Rajiwade

15

13

Hi Saurabh, please familiarise yourself with [writing an answer](https://stackoverflow.com/help/how-to-answer) before writing your next one! Enjoy your stay at SO :) – Diggy. May 14 '20 at 11:42
1

This is not an answer because the question is not about the library this answer mentions. – bad_coder Mar 08 '21 at 00:24
To add context, pycryptodome requires bytes to be passed in https://github.com/Legrandin/pycryptodome/issues/488 -- pycrypto does not. Highly recommend not uninstalling pycryptodome and instead passing in bytes, as pycrypto has security issues. – zvxr Aug 05 '21 at 18:10

Object type cannot be passed to C code - virtual environment

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