http://ppa.launchpad.net/

[Nils Kassube]

Steven Vollom wrote:
> >The packages are cryptographically signed with a GPG key. On your
> > machine there is a copy of GPG keys for the Ubuntu repositories.
> > However the key for the ppa repository is not included. According to
> > the instructions for installing KDE 4.2 for Intrepid you should add
> > the GPG key for the repository with the command
> > gpg --keyserver keyserver.ubuntu.com --recv-keys 493B3065 &&
> > gpg --export -a 493B3065 | sudo apt-key add -
>
> I am unable to understand the terminology of the previous comment.  I
> am sure it will be understood at some time in the future.  Now it is
> just an instruction that I must obey, even if I don't understand.

Maybe you can understand it better if you read something about digital 
signatures: <http://en.wikipedia.org/wiki/Digital_signature>. Granted, 
the topic is quite complicated, but maybe you can at least find out what 
a key is used for. And while this analogy 
<http://en.wikipedia.org/wiki/Asymmetric_key_algorithm#A_postal_analogy> 
is for encryption and not signatures, it may further help to understand 
what cryptographic keys are good for.


Nils