[STDS-P1619] Fwd: IEEE Security in Storage Working Group: Questions regarding P1619-D19

[Matt Ball <matt.ball@xxxxxxxx>]

Hi Folks,

We've had the following inquiry concerning P1619/D19.  Would someone be able to answer these questions and reply to the reflector?

Thanks,

-Matt

---------- Forwarded message ----------
From: Boaz Shahar
Date: 2008/4/28
Subject: RE: IEEE Security in Storage Working Group: Questions regarding P1619-D19
To: Matt Ball
Cc: Boaz Shahar

Thanks.

So I read the draft (P1619-D19), and the following questions occurred to me:

(All questions refer to IEEE P1619/D197, July October 2007)

-The relation between "data-unit" and "key-scope": The mapping between data unit and a key is one to one, or some data-units can be encrypted with the same key?

-What is the typical size of such a data unit? I understand it is outside the scope of this work, but you probably have a size in mind. Is that a disk sector?

-In line 30 and 31 page 3 there is statement says that the size of a data-unit is 2^128-2 128 bit block. On the next sentence it says that the size of the data-unit is 2^20 128 bit block. This seems to be a contradiction.

- j, the index of the 128 bit block within a data-unit starts from 0 or 1 (i.e. the first 128 bit block of P is xored  with AES(i) or with AES(i)*ALFA?)

-Since I (tweak value), Key1, Key2, are constant for a given data-unit, and j is sequentially incremented, it seems that within a certain data-unit it is enough to multiply each T by ALFA in order to get the next T. Is that correct? (i.e. T(n+1) = T(n)*ALFA )

 - In the formula: Cq ← 1 XTS-AES-blockEnc(Key, Pj, i, q)  Pj can be replaced by Pq, correct?

 

Thanks for your help, and best regards,

Boaz