After I opened succesfully tcp-port in firewall
and followed your guide, I managed to overcome
this error:
“W: GPG error: http://ppa.launchpad.net maverick Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY CBDFA02B432BB368″

This helped me a lot while trying to update ebox on my Ubuntu Lucid

Right I was working through this and a more general way in which to do this is as follows (I’m going to us SMPlayer as my example):

The SMPlayer PPA is located at:
https://launchpad.net/~rvm/+archive/smplayer

First we add it to the package manager as in the screen cast above in the Third Party tab. Next we are going to deal with getting the key. On that page there is a link called “Technical details about this PPA” which we click to bring up the “Signing Key” which is what we are going to need to use to search for the key we need for SMPlayer.

At the time of writing its: 1024R/E4A4F4F4

For the search we’ll only be interested in the part after the forward slash e.g. E4A4F4F4. Next we go to http://keyserver.ubuntu.com:11371/ and search for “0xE4A4F4F4″ (without the quotes obviously). This will bring up the link to the PGP key we are looking for and by clicking it we get our PGP key, which we can then add to our authenticated sources list as per the screen cast above. Then just do the same steps as done in the screen cast.