[openpgp] Re: Fwd: I-D list for Open Specification for Pretty Good Privacy notification: Changes to draft-gallagher-openpgp-code-point-exhaustion

Justus Winter <justus@sequoia-pgp.org> Thu, 20 March 2025 09:57 UTC

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From: Justus Winter <justus@sequoia-pgp.org>
To: Heiko Schäfer <heiko.schaefer@posteo.de>, openpgp@ietf.org
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Date: Thu, 20 Mar 2025 10:57:48 +0100
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Subject: [openpgp] Re: Fwd: I-D list for Open Specification for Pretty Good Privacy notification: Changes to draft-gallagher-openpgp-code-point-exhaustion
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Hi Heiko :)

Heiko Schäfer <heiko.schaefer@posteo.de> writes:

> I'm sure much discussion would be needed to positively decide in favor
> of the scheme proposed in
> draft-gallagher-openpgp-code-point-exhaustion.
>
> However, as I understand it, the only immediate question that this
> draft is effectively asking is: "do we want to reserve bit 8, for
> now?"
>
> I have not seen any compelling argument against this proposition, so
> far.

I think this solution is hasting (maybe to the point of creating) the
problem it is trying to solve.

Further, the proposed solution (for which reserving one bit now is the
precondition, so I think it is fair to also consider it), seems to
complicate parsing (and there is precedence on how OpenPGP very cleverly
encodes things like packet body lengths, S2K hash counts, S2K mechanism
type, AEAD block sizes), and I like parsing to become simpler, not more
complicated.

And, I believe section 5 of
draft-gallagher-openpgp-code-point-exhaustion-00 to be overly optimistic
regarding its completeness: attackers seem to be a clever bunch, and the
analysis missed or does not discuss not being able to compute
fingerprints for secret key packets.

Best,
Justus