I use Ubuntu 14.04 Desktop Edition.
Now I see Software Updater's message that it must be updated.
Then I get a message
requires installation of untrusted packages from unauthenticated sources
I'm quite new to Ubuntu and lately I've been struggling with software updater.
It lists the software to update but when I try to update gives the message
Requires installation of untrusted packages
Last night my internet connection was slow so I canceled Gimp installation (4.5 Mb/53Mb). But today when I try to click on Gimp install button in Ubuntu Software Center, this error came up "Requires ...