Subject: Shoring Up Hash Algorithm
From: "Santosh Chokhani" <[email-masked]>
To: <[email-masked]>
Cc: "Miles Smid" <[email-masked]>
Date: Thu, 10 Nov 2005 15:34:59 -0500
List-Id: <ietf-ltans.imc.org>

As you know, Carl Wallace gave a presentation on my behalf at the Nov 2005
IETF on how hash algorithms can be shored up for long term archive and
signature preservation.
 
One proposed method was the use of AES CBC mode.  Since the signature will
be computed over the last block of CBC mode, there are class of attacks an
adversary can use so that a different message has the same AES CBC last
block for the same IV and key.
 
Thus, I propose that we not use AES CBC crypto primitive.
 
The idea proposed should still work if the other crypto primitive in the
briefing and attributes to  
Krawczyk and Halevi is used.

Santosh Chokhani 
Orion Security Solutions, Inc. 
1489 Chain Bridge Road, Suite 300 
McLean, Virginia 22101 
(703) 917-0060  Ext. 35 (voice) 
(703) 917-0260 (Fax) 
[email-masked] 
Visit our Web site 
http://www.orionsec.com <http://www.orionsec.com/>