Subject: [openpgp] draft-irtf-cfrg-aead-limits lacks EAX and OCB

From: Daniel Kahn Gillmor <[email-masked]>
Date: Sat, 31 Jul 2021 01:08:14 -0400

Hi CFRG and OpenPGP folks--

In the CFRG meeting today, i noticed that the AEAD Limits draft does not
include a mention of EAX and OCB.

EAX and OCB are both candidates for inclusion in the forthcoming
cryptographic refresh of OpenPGP
(https://gitlab.com/openpgp-wg/rfc4880bis/-/blob/main/crypto-refresh.md).

I note that for OCB, RFC 7253 does include some suggestions of the kinds
of limits that are appropriate.

I'm not skilled enough with the kind of analysis that's happening in
these drafts to tell whether the guidance in 7253 translates into the
same sort of answers that draft-irtf-cfrg-aead-limits is trying to
systematize.

If it is, and CFRG folks find the limits in 7253 plausible, perhaps a
new section in the AEAD limits draft could import the relevant figures
and reference 7253?

I don't know of any comparable analysis for EAX, but if anyone can point
to some, i'd be interested in seeing EAX analyzed as well.

Sorry to not have the chops to analyze this myself, but i'm hoping that
someone in CFRG have enough capacity to at least look into it and tell
me why it doesn't match.

Regards,

        --dkg