Web lists-archives.com

Warning of packages that cant be authenticated during dist-upgrade

Trying to upgrade from 9.6 i get:

$ LANG=en sudo apt-get dist-upgrade

WARNING: The following packages cannot be authenticated!
  libbasicusageenvironment1 libgroupsock8 liblivemedia58 libusageenvironment3 libvlccore9 vlc-plugin-skins2 vlc vlc-plugin-qt vlc-l10n vlc-plugin-base vlc-data vlc-plugin-video-output libvlc5 vlc-bin   libvlc-bin phonon4qt5-backend-vlc vlc-plugin-fluidsynth vlc-plugin-notify vlc-plugin-samba vlc-plugin-video-splitter vlc-plugin-visualization vokoscreen mpv
Install these packages without verification? [y/N] y^C

What should i do?