On wheezy, after a day or so without running "apt-get update", I receive this warning when installing packages: WARNING: The following packages cannot be authenticated! libassuan0 libksba8 pinentry-gtk2 gnupg-agent gnupg2 Install these packages without verification [y/N]? Obviously, this is related to the stale mirror expiry mechanism. It's not clear to me what verifications are skipped when I answer yes. Is it just the up-to-date check, or more?