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Date: Wed, 2 May 2012 16:14:25 -0600
From: Vincent Danen <vdanen@...hat.com>
To: oss-security@...ts.openwall.com
Subject: Re: weak use of crypto in python-elixir can lead to
 information disclosure (CVE and peer review request)

* [2012-05-01 13:03:56 +0200] Florian Weimer wrote:

>* Florian Weimer:
>
>> * Vincent Danen:
>>
>>>>And you can group by encrypted column values in the database.  That's
>>>>why I'm not sure if it's actually possible to address this issue in a
>>>>satisfying manner.
>>>
>>> So the encryption can be more fine-grained than just per-table?  You can
>>> also do it per-column?  If that's the case, this does sound a lot uglier
>>> to deal with.
>>
>> This test case suggests to me that you have to specify the list of
>> encrypted columns explicitly:
>>
>> <http://elixir.ematia.de/trac/browser/elixir/trunk/tests/test_encryption.py>
>>
>> Based on this example, it's not clear to me if the current
>> implementation supports get_by with an encrypted column.  If this is a
>> feature which needs preserving, there is no apparent way around
>> convergent encryption.
>
>So it turns out that this passes the assert:
>
>        p = Person.get_by(password='r\\x9d\\xa8\\xb4\\x8d|\\xffp\\xf5\\x0e')
>        assert p.name == 'Jonathan LaCour'
>
>But this fails because p is None:
>
>        p = Person.get_by(ssn='123-45-6789')
>        assert p.name == 'Jonathan LaCour'
>
>This suggests to me that get_by on an encrypted column is not actually
>supported.
>
>The documentation doesn't describe which queries are supported:
><http://elixir.ematia.de/apidocs/elixir.ext.encrypted.html>

Thanks, Florian.  Seems like this thing is a bit messy.  I did post your
questions to the Red Hat bug, and there were some developer responses
there.

The long and short of it is that, despite what you've brought up, they
feel the fix is still appropriate.

https://bugzilla.redhat.com/show_bug.cgi?id=810013#c33 (for this
interested in the details).

-- 
Vincent Danen / Red Hat Security Response Team 

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