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Re: [STDS-P1619] Does XTS provide protection against watermarking?.

Cyril, thanks. Please excuse me for being so dense but, to be clear, you
are saying that XTS does provide protection against watermarking?

Garry 


-----Original Message-----
From: Cyril.Guyot@xxxxxxxxxxxxxx [mailto:Cyril.Guyot@xxxxxxxxxxxxxx] 
Sent: Tuesday, July 28, 2009 5:08 PM
To: Garry Mccracken
Cc: STDS-P1619@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-P1619] Does XTS provide protection against
watermarking?.

Hi Garry,

For simplicity, let's assume that the XTS "block" size is a multiple of
the
block size of the underlying block cipher such that we do not have to
deal
with ciphertext stealing.
Then such a watermarking attack would be a chosen plaintext attack on
the
indistinguishability of XTS from a perfect tweakable random permutation.
This would contradict the indistinguishability property of XTS under
chosen
ciphertext attack proven in section 3.3) of
http://csrc.nist.gov/groups/ST/toolkit/BCM/documents/comments/XTS/XTS_co
mments-Liskov_Minematsu.pdf

Best regards,
Cyril


 

             Garry Mccracken

             <Garry.Mccracken@

             WINMAGIC.COM>
To 
                                       STDS-P1619@xxxxxxxxxxxxxxxxx

             07/28/2009 09:42
cc 
             AM

 
Subject 
                                       [STDS-P1619] Does XTS provide

             Please respond to         protection against watermarking?.

              Garry Mccracken

             <Garry.Mccracken@

               WINMAGIC.COM>

 

 

 





Hi, does XTS provide protection against watermarking
(http://en.wikipedia.org/wiki/Watermarking_attack )?

http://en.wikipedia.org/wiki/Disk_encryption_theory
  mentions watermarking under CBC but doesn't say XTS protects against
watermarking.

Does XTS provide any protection against watermarking?

Garry