I'm trying to install different softwares found on Ubuntu Software Centre but I always get back the "Requires installation of untrusted packages" message after entering the pwd. That message pops up several times either after hitting "OK" or "Repair" button. The installation doesn't simply take place.
I tried the installation thru Terminal as suggested somewhere using the details in the error message but without success - here is the case of Stellarium software:
skround@HP-EliteBook-2530p:~$ apt-get install stellarium stellarium-data
E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied)
E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?
Any suggestion? Thanks in advance