https://github.com/matrix-org/synapse/issues/10389

I already resolved this issue years ago... made the package, which is now unmaintained.

matrix-archive-keyring (1:2019.04.16+ds.0.1) UNRELEASED; urgency=medium

  * New upstream key (2019-04-16).
  * Fix Lintian informative warnings.

 -- Linda Lapinlampi <linda@lindalap.fi>  Fri, 19 Apr 2019 07:16:14 +0000

matrix-archive-keyring (1:2015.06.11+ds.1) unstable; urgency=low

  * Initial release in Debian (contrib). (Closes: #922155)
  * Standards-Version 4.3.0.2 and Lintian free.
  * debhelper compat level 12.
  * matrix-archive-keyring: OpenPGP keys for package verification
    * Installs a keyring to the /usr/share/keyrings directory.
    * Prompts the user about trust anchored keys in APT's trusted.gpg and
      trusted.gpg.d files, then removes them.
    * Advanced users: Provides a debconf(1) template to reconfigure the
      keyring as a system trusted APT keyring. (Default: false)
  * matrix-archive-config: APT configuration
    * Installs an apt_preferences(5) file (a symbolic link from APT).
      * Pinned to matrix.org origin.
      * Pinned to priority 100.
    * Installs a sources.list(5) file (a symbolic link from APT).
      * Signed-By a keyring from matrix-archive-keyring.
  * Aware of the APT configuration via apt-config(8).

  * Notable changes since pre-releases prior to uploading to Debian:
    * Added bug-scripts for reportbug(1).
    * Changed version to match the date on the keys, not the upload date found
      on Matrix.org's HTTP servers (epoch increase, backwards incompatible).
    * +ds.x version numbering for Debian Source to match a common practice.
    * Fixed data loss on matrix-org.list (a typo in a test case, which led to
      the config migration code almost never being executed properly).
    * Added standard error output on encountering Debian Bug#696332 in
      lsb_release (re-discovered while testing the change mentioned before).
    * Added debian/copyright disclaimer for contrib area.

 -- Linda Lapinlampi <linda@lindalap.fi>  Thu, 21 Feb 2019 13:11:49 +0000

Related Debian bug: #922155 - ITP: matrix-archive-keyring -- OpenPGP archive key for the Matrix.org package repository

The funny thing is two years ago you (New Vector people) refused my idea for whatever reason

In reply to @lindalap:midov.pl
I know this isn't #synapse:matrix.org or #synapse-dev:matrix.org but I think you'll understand why I'm here

In reply to @emorrp1:freedombox.emorrp1.name
Additionally, I was going to say there's not much point in having an ever growing list of foo-archive-keyring and point you at the new extrepo tool, then I saw it's already there element.yaml. So all that needs to happen from the Debian side is to encourage people to use that and then update the key in the data repo.

Instead of explaining myself, I'll just blame you for being new to incooperation and conflicts of interest with New Vector.

My package predated the extrepo tool. Thanks for letting me know about it.

In reply to @paul:luon.net
I have done the cargo-deb packaging of Conduit, but am interested in turning that in real packaging