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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