title: Can't verify pgp signature
body: <p>I downloaded rsync 3.1.3 from the <a href="https://rsync.samba.org" rel="nofollow noreferrer">official website</a> and the relative signature but I am not able to verify the signature. </p>
  
  <p>This does not work</p>
  
  <pre><code>$ gpg --verify signature.sig rsync.tar.gz 
  gpg: unknown armor header:  Version: GnuPG v1
  gpg: Signature made Sun Jan 28 23:57:59 2018 UTC using DSA key ID 4B96A8C5
  gpg: Can't check signature: public key not found
  </code></pre>
  
  <p>I looked at <a href="https://www.gnupg.org/gph/en/manual/x135.html" rel="nofollow noreferrer">this link</a> and so I tried these commands, not working:</p>
  
  <pre><code>$ gpg --output rsync.tar.gz --decrypt signature.sig 
  gpg: unknown armor header:  Version: GnuPG v1
  Detached signature.
  Please enter name of data file: rsync.tar.gz 
  gpg: Signature made Sun Jan 28 23:57:59 2018 UTC using DSA key ID 4B96A8C5
  gpg: Can't check signature: public key not found
  
  $ gpg --output rsync.tar.gz --verify signature.sig 
  gpg: unknown armor header:  Version: GnuPG v1
  gpg: no signed data
  gpg: can't hash datafile: file open error
  </code></pre>
  
  <p>What should I do?</p>