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Re: padding values

> From: Stephen Kent <kent@bbn.com>
> 	I've looked at all the message traffic since the Memphis meeting,
> and I do not see any reference to padding being algorithm-specific, as you
> suggest.

Steve,  I'd say you didn't look very hard.  Paging backwards through the
text of my May archive, the most recent I saw was:

    Date: Thu, 22 May 97 11:27:27 EST
    From: "Whelan, Bill" <bwhelan@nei.com>
    Message-Id: <9704228643.AA864325641@netx.nei.com>

    ...  ESP may define restrictions on the length (e.g. a multiple of eight
         bytes) of the Opaque Payload Data, but otherwise not define content.

         Individual Transform documents would provide definitions for how the
         Opaque Payload Data is defined and would cover any needed fields
         including:
          - Initialization Vector - Optional
          - Payload Data - Mandatory
          - Padding - Optional
          - Next Header - Mandatory

I'm pretty sure we had a discussion last month, too, along with padding
the IV to 32 or 64 bit boundaries.

I'll find and summarize the rationale for integer padding in a separate
message, as those messages by Wagner, Karn, and Baldwin (and the other
discussants) are about a year and a half old....

The integer pad values have long been represented in the
    draft-simpson-esp-des3-x-00.txt
that was out there for over a year, and many folks have implemented.


>       Still, the issue you raise is a good one, i.e., do we want to leave
> definition of the contents of the padding field to the algorithm, or
> standardize it in the ESP spec. ...

More important, to me anyway, is that we cannot know of there is some
other padding feature that will be required by some future transform.
The need for padding (and the block size) is intimately tied to the
algorithm, not the ESP headers.  We need to know how long it is, but
predicting contents for all future algorithms is beyond us.

WSimpson@UMich.edu
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BSimpson@MorningStar.com
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