_randfunc attribute with a pickled rsa key

[Frédéric Lang]

I try to save and restore private key in file. So i use pickle module. And then when i crypt a message with dumped private key and when i try to decrypt it, pycrypto answer "_RSA object has not _randfunc attribute"

After long exam, i find problem from pickle module. So i write a little code exam like this

#!/usr/bin/env python
#-*- coding: utf-8 -*-

from Crypto import Random
from Crypto.PublicKey import RSA
import pickle
rng=Random.new().read
key=RSA.generate(1024, rng)

print dir(key)
print dir(pickle.loads(pickle.dumps(key)))

And the result:
['__doc__', '__eq__', '__getattr__', '__getstate__', '__init__', '__module__', '__ne__', '__repr__', '__setstate__', '_blind', '_decrypt', '_encrypt', '_randfunc', '_sign', '_unblind', '_verify', 'blind', 'can_blind', 'can_encrypt', 'can_sign', 'decrypt', 'encrypt', 'exportKey', 'has_private', 'implementation', 'key', 'keydata', 'publickey', 'sign', 'size', 'unblind', 'validate', 'verify']
['__doc__', '__eq__', '__getattr__', '__getstate__', '__init__', '__module__', '__ne__', '__repr__', '__setstate__', '_blind', '_decrypt', '_encrypt', '_sign', '_unblind', '_verify', 'blind', 'can_blind', 'can_encrypt', 'can_sign', 'decrypt', 'encrypt', 'exportKey', 'has_private', 'implementation', 'key', 'keydata', 'publickey', 'sign', 'size', 'unblind', 'validate', 'verify']

So effectively, the _randfunc attribute is not in second display.

The problem is same if i use copy.deepcopy().

Best regards
Thanks

[Legrandin (gooksankoo)]

The problem you mention has been fixed in a recent patch:

https://github.com/dlitz/pycrypto/commit/db52ac71e804e85ace3edd772d2e78055972ac2c

Still, I wouldn't use pickle in the first place.
Using exportKey() and importKey() is much more secure and robust.

[Frédéric Lang (fr-lang)]

Good evening. Thanks for your answer.
Effectively, yesterday (friday) i found the function exportKey() and
importKey() (sorry, i found Crypto only thuersday) and so i changed my
operations. Now all is ok. I can export and import without any problem.

Thank-you for your work. I was looking for crypt opérations since 2
weeks. I tryed Python-GnuPG, PyME and so Thuersday i found Crypto and i
see it's really what i wanted. Light, quick, simply functions, very very
good.

Best Regards

PS: Sorry for my english, i'm french...

Le 25/05/2013 18:30, Legrandin a écrit :
> The problem you mention has been fixed in a recent patch:
>
> https://github.com/dlitz/pycrypto/commit/db52ac71e804e85ace3edd772d2e78055972ac2c
>
> Still, I wouldn't use pickle in the first place.
> Using exportKey() and importKey() is much more secure and robust.
>

--
Frédéric Lang
http://fr.lang.free.fr
<email address hidden>