firefox not verified?

[Richard Hector]

Hi all,

Sorry to interrupt with a little distribution issue ...

I'm getting verification errors trying to upgrade firefox (aptitude
safe-upgrade, or aptitude install -t jessie-backports firefox)

/etc/apt/sources.list.d/mozilla-backports.list:
deb http://mozilla.debian.net/ jessie-backports firefox-release

pkg-mozilla-archive-keyring is installed (version 1.1) and looks good:

# gpg --check-sigs --fingerprint --keyring
/etc/apt/trusted.gpg.d/pkg-mozilla-archive-keyring.gpg --keyring
/usr/share/keyrings/debian-keyring.gpg pkg-mozilla-maintainers
pub   4096R/06C4AE2A 2010-11-20 [expires: 2019-11-13]
      Key fingerprint = 85F0 6FBC 75E0 67C3 F305  C3C9 85A3 D265 06C4 AE2A
uid                  Debian Mozilla team APT archive
<pkg-mozilla-maintainers at lists.alioth.debian.org>
sig!3        06C4AE2A 2012-11-14  Debian Mozilla team APT archive
<pkg-mozilla-maintainers at lists.alioth.debian.org>
sig!         A6AA8C72 2010-11-20  Mike Hommey <glandium at debian.org>

1 signature not checked due to a missing key

I had a proxy (apt-cacher-ng) configured, but I've commented that out
and re-updated, with no change:

# apt-get install -t jessie-backports firefox
Reading package lists... Done
Building dependency tree
Reading state information... Done
Suggested packages:
  fonts-stix otf-stix mozplugger
The following packages will be upgraded:
  firefox
1 upgraded, 0 newly installed, 0 to remove and 220 not upgraded.
Need to get 45.0 MB of archives.
After this operation, 2,048 B of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
  firefox
Install these packages without verification? [y/N]

Any tips?

Thanks,
Richard