Sunday, December 28, 2025

Two Thoughts on Ubuntu Signing Keys

Here’s something I don’t get: why is there a trusted “2012 CD signing key” on my Ubuntu 24.04 machines, when there is also a “2018” signing key?  Shouldn’t this be a transition that could have completed within five years?  Shouldn’t we be able to tie the 2012 key to a specific repository set, instead of all packages?  The latter includes PPAs and I really wish neither of those CD signing keys were valid for that purpose.

The cryptographic domains should be separated:

  1. One CD signing key, tied to the CD/DVD packages
  2. One online release signing key, tied to the Ubuntu main/security sources
  3. One key per PPA, tied to that PPA

Deprecating globally-trusted keys for PPAs is a good step, but the globally-trusted release keys (especially ones that are over a decade old) should be cleaned out immediately as well.

Semi-related pro tip: extrepo

Many packages are supported in extrepo, which handles the keys for you.  There is no need for arcane gpg format-conversion commands, no worrying about whether it goes into /usr (incorrect under Unix philosophy, but widely recommended) or /etc, no manually editing sources files, and especially no cursed curl | bash invocation.

$ sudo apt install extrepo

And then you can do stuff like:

$ extrepo search github
$ sudo extrepo enable github-cli
$ sudo apt install --update gh

This is especially useful for upstreams that distribute an official deb package, outside of PPAs.  I aim to get the code from as close to the source as possible, where the distro itself doesn’t suit my needs.

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