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From: Mark Borgerding <mark@borgerding.net>
To: linux-kernel@vger.kernel.org
Subject: Re: PROBLEM: AES cryptoloop corruption under recent -mm kernels
Date: Fri, 16 Jan 2004 12:10:08 -0500	[thread overview]
Message-ID: <40081AF0.5060907@borgerding.net> (raw)
In-Reply-To: <Xine.LNX.4.44.0401161039480.20623-100000@thoron.boston.redhat.com>

James Morris wrote:

>On Fri, 16 Jan 2004, Mark Borgerding wrote:
>
>  
>
>> From looking through the cryptoloop code, it looks like the IV for CBC
>>mode is always the sector index.  It seems this could be weak against
>>chosen plaintext attacks, as well as allowing an attacker to know which
>>cipher blocks started any changes between two snapshots of the
>>ciphertext.  I discuss ECB, since I wouldn't consider using it.
>>    
>>
>
>Eli Biham has suggested encrypting the sector numbers, see
>http://people.redhat.com/jmorris/crypto/cryptoloop_eli_biham.txt
>
>
>
>- James
>  
>

This does not defend against a dictionary attack.

The IV is still deterministic for a given sector and hypothesized 
password. 
Thus the ciphertext for a given plaintext at that sector is still 
deterministic.

Thinking of it another way, this is equivalent to CBC mode having two 
IVs: the first one being the sector number, the second a block of zeros.


- Mark


  reply	other threads:[~2004-01-16 17:10 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-01-14 20:36 PROBLEM: AES cryptoloop corruption under recent -mm kernels Jim Faulkner
2004-01-14 20:41 ` Jim Faulkner
2004-01-14 20:52 ` Andrew Morton
2004-01-14 23:30   ` Jim Faulkner
2004-01-15  2:44   ` Matthias Hentges
2004-01-15 16:57 ` Jari Ruusu
2004-01-15 17:24   ` Jim Faulkner
2004-01-15 20:33     ` Jari Ruusu
2004-01-15 22:59       ` Hans Reiser
2004-01-16 14:21       ` Mark Borgerding
2004-01-16 15:42         ` James Morris
2004-01-16 17:10           ` Mark Borgerding [this message]
2004-01-17  2:47             ` David Wagner
2004-01-17 16:13               ` Mark Borgerding
2004-01-17 20:39             ` Shawn Willden
     [not found]       ` <4007EBDA.2060308@borgerding.net>
     [not found]         ` <4007F79C.80A5DE72@users.sourceforge.net>
     [not found]           ` <400818AA.9080009@borgerding.net>
2004-01-16 21:43             ` Jari Ruusu
2004-01-15 18:16   ` James Morris
2004-02-01 17:19     ` Pasi Kärkkäinen
2004-02-01 19:40       ` markus reichelt

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