From: Maxime Devos <maximedevos@telenet.be>
To: me@tobias.gr, 57091@debbugs.gnu.org, ludo@gnu.org
Subject: bug#57091: Git authentication reports subkey fingerprints
Date: Thu, 11 Aug 2022 17:07:12 +0200 [thread overview]
Message-ID: <fc12e652-af4b-c107-c8cb-06730f75f084@telenet.be> (raw)
In-Reply-To: <5330DDA4-F1AD-4F99-B6A5-5CDA2D975983@tobias.gr>
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On 11-08-2022 13:17, Tobias Geerinckx-Rice wrote:
> Apologies if I'm wildly off the mark here. But then I'd like to hear some plausible threat models. Maxime?
Here's a problem with allowing subkeys, if that's what you mean:
* Expiration times and GPG-level revocation must be ignored (for
time-travel, and pulling from an old Guix), similarly to why it must
be ignored for when no subkeys are used
* Someone used to GPG-style subkeys generates a new subkey to replace
old expired subkey or revokes old subkey, without keeping in mind
that Guix doesn't take that in account.
* An attacker uses a compromised-but-revoked-or-expired subkey to
compromise the channel.
Expiration times might be solvable by taking the commit time of the
previous commit as 'current time' (not the commit that was signed,
otherwise an attacker could just lie). I don't know a solution for
GPG-level revocation of old subkeys but I haven't looked either.
Another problem:
* When replacing the key in the 'keyring' branch with an 'updated' key
that contains the new subkey, we have to be careful to never remove
old subkeys, to avoid breaking time travel or pulling from old versions.
Greetings,
Maxime.
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next prev parent reply other threads:[~2022-08-11 15:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-09 21:07 bug#57091: Git authentication reports subkey fingerprints Ludovic Courtès
2022-08-09 21:20 ` Maxime Devos
2022-08-11 10:24 ` Ludovic Courtès
2022-08-11 11:17 ` Tobias Geerinckx-Rice via Bug reports for GNU Guix
2022-08-11 11:33 ` Tobias Geerinckx-Rice via Bug reports for GNU Guix
2022-08-11 15:07 ` Maxime Devos [this message]
2022-08-11 16:31 ` Tobias Geerinckx-Rice via Bug reports for GNU Guix
2022-08-11 18:10 ` Maxime Devos
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