The same caveat applies to -updates, but there is a question of whether
we should ship 2.8.0 as this or make 2.8.0 different, I did not push a
tag for it yet.

i.e. given that this is a stable release update that will break PPAs
users currently have warnings for, it might make sense to make it break
that a couple months down the road after we have a transition period,
i.e. we can "timebomb" things by making apt treat the weak keys as
expiring in August (August because we really want this sorted out by the
point release when the big wave of 22.04 users upgrades).

We could also introduce a new version of software-properties-common that
adds PPA key refresh. We should then trigger that by apt postinst, or in
the software-properties-common postinst. I do not believe we need to
enforce a strict ordering relationship here, so 2.8.0 as is should
technically be good to go.

It's understandable that breaking existing repositories in a stable
release is not optimal, however the warnings don't work as a security
mechanism - we do not show you which weak keys are trusted, just which
weak keys were used to sign the repository:

Hence if you have a 1024R key and a 4096R that can sign a repository,
but it's signed by the 4096R key now, you don't see the 1024R key, and
an attacker could resign the repository with it and silently attack you.

So this is something we do need to target for the first point release;
we want users upgrading from 22.04 to not end up in the transitional
stage where they have warnings.

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to apt in Ubuntu.
https://bugs.launchpad.net/bugs/2060721

Title:
  APT 2.8.0: Promote weak key warnings to errors

Status in apt package in Ubuntu:
  Incomplete
Status in apt source package in Noble:
  Incomplete

Bug description:
  ⚠️ Only land this in the release/updates pocket after PPAs have been
  resigned

  (This bumps the apt version to 2.8.0. APT uses the odd/even number
  system, with 2.7.x being the development series for 2.8, and this is
  the only change left for the 2.8 release, safe for some minor
  translation/test suite improvements)

  (This will be uploaded after the beta and may be released before noble
  release, as a zero day SRU or within the weeks following the release)

  [Impact]
  APT is currently just warning about keys that it should be rejecting to give 
Launchpad time to resign PPAs. This needs to be bumped to an error such that 
the crypto policy is fully implemented and we only trust keys that are still 
being trusted. #2055193

  A warning provides some help right now to third-parties to fix their
  repositories, but it's not *safe*: A repository could have multiple
  signing keys and be signed by a good key now, then later, a previous
  key still in trusted.gpg.d could be revoked and we'd degrade to
  warnings, which, given that we update in the background automatically,
  the user may not see.

  Other fixes:
  - The test suite has been made less flaky in two places
  - Documentation translation has been unfuzzied for URL changes in 2.7.14

  [Test plan]
  The vast regression test suite prevents regression in other components. 
Additional tests are:

  1. (promotion to error) Take a repository that has a weak key warning, 
upgrade apt and check that it is an error
  2. (still valid) Check that the main Ubuntu repositories and/or resigned PPAs 
work correctly.

  We don't have any tests for the test changes or the documentation
  translation URL unfuzzying.

  [Where problems could occur]
  apt will start to fail updates of repositories with weak signing keys, but it 
will have warned users about that before. Given that it is still early in the 
cycle, and we only enable updates for 24.04.1, this seems the right tradeoff 
for future security.

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