The approach is very simple:
detect PPA installation and automatically fetch the corresponding signing key, so the package inventory can be reloaded successfully at the end of the process.
No magic, the same look and feel ubuntu users are used to, and at the end, the job is done with no risks.
PPAs are Third-party Softwares
In this example, we will use Ubuntu Mozilla Daily PPA, so you can add:The repository deb line listed on the PPA page:
Or simply use the supported shortcut for PPAs:
Click on Add Source and that's it, PPA and signing key enabled.
(right now the Authentication tab does not reload automatically, you have to click Restore Defaults to see the new key. I'm working on a fix).
A testing version of the package is available in my Experimental PPA (expand the source package row and install the deb file directly with gdebi, then you are safe to test the application on the same PPA)