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?