Authentication problem with my PPA

Question

I created a package and uploaded it to my PPA. After it got built, I went to install it, but was faced with this message:

******@******-laptop:~$ sudo apt-get install stackapplet
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following NEW packages will be installed:
  stackapplet
0 upgraded, 1 newly installed, 0 to remove and 31 not upgraded.
Need to get 17.7kB of archives.
After this operation, 106kB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
  stackapplet
Install these packages without verification [y/N]?

My question is... why is it warning me about the packages not being verified? And how can I fix this?

Answer 1

Most likely this is caused by a missing PGP key in your APT keyring. You can add the key with the following command:

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 72D340A3

Of course you need to replace the key with your PPA key.

Also, the following command will add the key automatically:

sudo add-apt-repository ppa:user/ppa-name

After adding the key, you need to run apt-get update to download and verify the signature.