WARNING: The following packages cannot be authenticated!

Today, when I tried to <code>aptitude install</code> a package on Ubuntu the response was “WARNING: The following packages cannot be authenticated!”

I received a similar warning when I tried to use Synaptic Package Manager.

I checked and made sure that the software was trying to install from the official repository.

I’m not really sure of the cause, or when it started happening, but I have seemed to have fixed this by cleaning out most of the keys.

Searching the web, I found out about SecureApt, apt-key, but didn’t really find myself closing to a solution until I looked at the contents of /etc/apt/trusted.gpg .

In Software Sources (System > Administration >) I found a long list of “trusted software providers” including what looked like some duplicated.

I noted what they were and removed them all except the first one, 437D05B5 2004-09-12 Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com> and closed the application.

It was then working. It seems that I could have likely removed them all and then <code>sudo aptitude reinstall ubuntu-keyring</code>.

After I added back the keys for Google Linux Software and Wine for IEs4Linux.