Error when trying to install GIMP in Ubuntu
 

When trying to install GIMP from the Ubuntu Software Center,
I get the error "Requires installation of untrusted packages" and "The action would require the installation of packages from not authenticated sources."

In the details it gives:
gimp gimp-data libbabl-0.0-0 libgegl-0.0-0 libgimp2.0

Anyone know how to solve this?

Nevermind, I solved it by marking "source code" in the "Software Sources" options.

Then you might as well mark this thread as [SOLVED]. That's in the "Thread Tools" button at the top.