Re: Cohen's paper on byte order

From: Mok-Kong Shen (mok-kong.shen@t-online.de)
Date: 04/06/03


From: Mok-Kong Shen <mok-kong.shen@t-online.de>
Date: Sun, 06 Apr 2003 15:38:44 +0200


"Douglas A. Gwyn" wrote:
>
> Mok-Kong Shen wrote:
> > But is that a problem 'specific' to AES??
>
> Yes! Haven't you been paying attention? Other
> protocol specs for information interchange are
> careful to spell out all the details necessary
> for correct communication of the formatted data.
> AES does not. It is missing an essential
> component. Putting it another way, it was an
> excess of abstraction to change the specification
> from the original one, that concerned bits in
> storage, into one about abstract mathematical
> objects without a definite mapping between the
> abstract objects and actual storage objects.
> The connection with reality was thereby lost.

O.k. Let me ask the following question: If one
has any application (crypto or not) that generates
information as a sequence of bytes, does that
application also have to specifiy 'all the details
necessary for correct communication of the formatted
data' in order to be formally correct (fulfilling
requirements of software engineering)? I don't
think so, particulary for programs that process
texts, e.g. in natural language processing. And
I don't yet understand why you said 'formatted data'.
What an AES algorithm produces is in my view simply
a sequence of bits or bytes, 128 bits with numerical
'tags'0-127, no more, nor less. As such it is not
formatted. You could format it in arbitrary ways
you like (of course necesarily to be consistent with
that of your communication partner), e.g. as hex
digits for convenient display on paper, isn't it?

M. K. Shen



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