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Re: [openpgp] Transport public keys inside the message body

Simon Josefsson <simon@josefsson.org> Thu, 15 February 2024 08:01 UTC

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From: Simon Josefsson <simon@josefsson.org>
To: Kai Engert <kaie@kuix.de>
Cc: "openpgp@ietf.org" <openpgp@ietf.org>
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Date: Thu, 15 Feb 2024 09:02:03 +0100
In-Reply-To: <33b847dd-2dfc-4741-a415-d4636642fef1@kuix.de> (Kai Engert's message of "Thu, 15 Feb 2024 08:31:36 +0100")
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Subject: Re: [openpgp] Transport public keys inside the message body
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Kai Engert <kaie@kuix.de> writes:

> I suggest to specify a way to transport public keys as part of the
> message body of a MIME message. I assume it would be necessary to
> amend the PGP/MIME specification to do so?

I agree this is useful -- getting keys from people who send me signed
PGP email these days is challenging.  Including the public PGP key in
every e-mail is not that costly.

I re-read RFC 3156 and one way to do this is "extend" it by allowing
putting a public key block before or after the '-----BEGIN PGP
MESSAGE-----' block, and say that MUAs can parse those blocks to find
keys.  Yes, that is a bit ugly, but overall complexity is lower than
having multipart MIME blobs with an extra application/pgp-keys
component, and solves the problem of locating which public key was (by
the sender) intended for use with the signature.

Maybe the old OpenPGP: e-mail header with fingerprint and URL should be
revived...  https://josefsson.org/openpgp-header/ and
https://datatracker.ietf.org/doc/html/draft-josefsson-openpgp-mailnews-header

/Simon

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