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Re: Derived versus Explicit IV



> Date: Thu, 24 Jul 1997 22:01:22 -0400
> From: "Theodore Y. Ts'o" <tytso@MIT.EDU>
>
>    Date: Thu, 24 Jul 97 13:11:26 GMT
>    From: "William Allen Simpson" <wsimpson@greendragon.com>
>
>    The extra 64-bit explicit IV was mandated by the current WG chair.  It
>    ruined word alignment for IPv6.
>
> For the record, there is no problem with IPv6 alignment with the current
> version of ESP with the 64-bit explicit IV.  Check the the current I-D's
> for yourself and see.
>
For the record, I have corresponded with Ted, and he admits that he
mis-interpreted my quoted text.  His admonishment was out of order.

The quote was taken out of context.  The quote did not concern the
(now) current I-D's, nor the (now) current WG chairs.

The quote, in context:

    Historically, RFC-1829 was based on swIPe, which had a sequence number.

    The extra 64-bit explicit IV was mandated by the current WG chair.  It
    ruined word alignment for IPv6.  It was not requested by any person in
    the WG.

    The authors were not happy about this, but agreed to add the option to
    get the publication out the door.  ...

You will note that the verb tense everywhere in these paragraphs is
"past" -- was, had, ruined, was not, were not, agreed.

That section concludes with "Thus, in the olden days, ....".  Later
sections use present tense.  I thought them reasonably well distinguished.
I had nice consistent terms, and transitional sentences.

In the recent drafts, everyone will note that _BOTH_ derived and
explicit IVs align appropriately for IPv6.  It is not an issue with the
(now) current drafts.

My main point still stands, however, that the previous explicit IV is
not conformant nor interoperable with the current group of transforms.

That an explicit IV was mandated by an earlier WG chair is not a good
reason why the (now) current chairs should mandate one.  On the
contrary, one might expect great hesitation to repeat the same mistake.

WSimpson@UMich.edu
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BSimpson@MorningStar.com
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