Problem with gpg and apt-get update - missing keys?

Question

I do not know how, but I managed to mess up apt-get. Executing

sudo su
apt-get update

I get errors like the following

W: http://security.debian.org/dists/stretch/updates/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg are ignored as the file is not readable by user '_apt' executing apt-key.
W: GPG error: http://security.debian.org stretch/updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9D6D8F6BC857C906 NO_PUBKEY 8B48AD6246925553
W: The repository 'http://security.debian.org stretch/updates InRelease' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.

for the repositories:

http://deb.debian.org/debian stretch-updates InRelease
http://deb.debian.org/debian stretch-proposed-updates InRelease
http://deb.debian.org/debian stretch Release

I understand that there are some keys missing and I tried to create them with

gpg --keyserver keyring.debian.org --recv-keys 8B48AD6246925553

but as a reply I got

gpg: no valid OpenPGP data found.
gpg: Total number processed: 0

Additionally I have another problem with http://deb.debian.org/debian stretch/main Translation-en:

E: Failed to fetch http://deb.debian.org/debian/dists/stretch/main/i18n/Translation-en  BZ2_bzread: /var/lib/apt/lists/partial/deb.debian.org_debian_dists_stretch_main_i18n_Translation-en.bz2 Read error (-5: DATA_ERROR_MAGIC)

which seems to have to do with the Zip-format!? No idea what I did.

Any ideas/hints how to fix my two problems?

Cheers, Christian

Answer 1

The simplest way to fix this is to manually download the debian-archive-keyring package and install that, then run apt update again. You’ll also need to restore the permissions on /etc/apt/trusted.gpg:

sudo chmod 444 /etc/apt/trusted.gpg

The Translations problem is a bad file on the servers, there’s nothing you can do about that.