Subject: Re: PGP Partitioned Encoding Format

From: Ingo Luetkebohle <[email-masked]>
Date: Tue, 01 Mar 2005 12:17:21 +0100

Am Montag, den 28.02.2005, 15:35 -0800 schrieb "Hal Finney":
> One other example where Partitioned Encoding is often the best encoding to
> use is when sending PGP email to mobile devices. Because the two primary
> standard formats for secure email, PGP/MIME and S/MIME, encrypt the entire
> body of an email including attachments as one part, a mobile device is
> prevented from downloading only specific segments of the message which
> can be very desirable in low-bandwidth scenarios.

Thats current practice but you make it sound as if its required by the
standard.  From my reading of RFC3156, it is not.  While the
"multipart/encrypted" part has to have exactly one encrypted subpart, it
may occur several times in any given message.

Both approaches have their drawbacks -- its certainly more telling to
have every attachment encrypted seperately and its also more work for
the handling application.  In any case, its hard to tell what will be
more appropriate for the recipient.  However, advocating a non-MIME
format because of assumptions about the recipient seems ill-advised to
me.  

Instead of putting in a notation requesting "partitioned", you might
request the "other way" of packaging a MIME-message just as well.
If, however, you want to document "partitioned" purely as a backwords-
compatibility thing, please don't put in language that makes it sound
like it might be a good idea for future use.

Sorry, but I've had one too many inline-PGP vs. PGP/MIME discussions to
stay calm here ;-)

regards

-- 
"There is no limit to what a man can do or how far he can go if he
doesn't mind who gets the credit." - Robert Woodruff

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From: Werner Koch <[email-masked]>
Date: Tue, 01 Mar 2005 17:18:35 +0100

> request the "other way" of packaging a MIME-message just as well.

Won't work either with Outlook. You need at least a way to display
signed message even to users without the ability to check the
signature.  All PGP/MIME stuff does not work with that beast unless
someone figures out how their MAPI can be forced to do certain things.
It is really a pitty that for just one MUA one need to resort to such
pragmatic workarounds.

Shalom-Salam,

   Werner

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From: Ingo Luetkebohle <[email-masked]>
Date: Tue, 01 Mar 2005 19:36:04 +0100

Am Dienstag, den 01.03.2005, 17:18 +0100 schrieb Werner Koch:
> Won't work either with Outlook. 

Sorry, I didn't mean to imply it would.  I know that all sorts of
work-arounds have to be done for Outlook.

The only thing I have an issue with is the implication that this sort of
encoding might actually be good for other purposes.   For the example
given (mobile devices), a different usage pattern for PGP/MIME should do
the trick just as well.

Ingo