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Message-ID: <20120430215744.GK13910@redhat.com>
Date: Mon, 30 Apr 2012 15:57:44 -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)
* [2012-04-28 13:58:15 +0200] Florian Weimer wrote:
>> CFB mode is only secure if the the IV is unpredictable and different
>> for every message.
>
>There are a few additional requirements. Without some form of message
>authentication, chosen-ciphertext attacks are still possible even with
>a random IV.
I'm no crypto expert, so I don't have a comment on this (although I did
note this message in our bug, so that those smarter than I can look at
it).
>> Because of this, and because the encryption key is shared for each
>> database table (fields and rows), the same plaintext prefix is
>> always encrypted to an identical and corresponding ciphertext
>> prefix. As a result, an attacker with access to the database could
>> figure out the plaintext values of encrypted text.
>
>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.
--
Vincent Danen / Red Hat Security Response Team
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