title: GPG Keys Missing, Can't Be Found on Keyserver Either
body: <p>So this error has been popping up a lot so I thought I'd resolve it:</p>
  
  <pre><code>W: GPG error: http://cfengine.com precise Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 535C743689107B44
  </code></pre>
  
  <p>So I did some research and tried these solutions</p>
  
  <pre><code>gpg --keyserver hkp://keyserver.ubuntu.com:80 --recv 535C743689107B44
  </code></pre>
  
  <p>and </p>
  
  <pre><code>sudo apt-key adv --keyserver.ubuntu.com --recv-keys 535C743689107B44
  </code></pre>
  
  <p>both of which terminated with this message</p>
  
  <pre><code>gpgkeys: key 535C743689107B44 not found on keyserver
  gpg: no valid OpenPGP data found.
  gpg: Total number processed: 0
  </code></pre>
  
  <p>Any insights are appreciated</p>