Update manager won't install from un-authenticated sources [duplicate]

My update manager shows updates available. When I click on install updates it shows the following and does not update.

The action would require the installation of packages from not authenticated sources.

in details:

accountsservice cups cups-bsd cups-client cups-common cups-ppdc empathy empathy-common libaccountsservice0 libcups2 libcupscgi1 libcupsdriver1 libcupsimage2 libcupsmime1 libcupsppdc1 nautilus-sendto-empathy scribus-trunk

How to get updates ?

To update from unauthenticated sources, use this command :

sudo apt-get update && sudo apt-get upgrade --allow-unauthenticated

See the Ubuntu manual page for apt-get to get more details about --allow-unauthenticated option