title: NO_PUBKEY and KEYEXPIRED
body: <p>When I try to use <code>apt-get update</code> command on Debian I find myself in a kind of error cycle with these two errors: NO_PUBKEY and KEYEXPIRED</p>
  
  <p><code>W: There is no public key available for the following key IDs:
  4D270D06F42584E6
  W: GPG error: http://archive.debian.org lenny/updates Release: The following signatures were invalid: KEYEXPIRED 1356982504
  W: GPG error: http://archive.debian.org lenny/volatile Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY DFD993306D849617
  W: Failed to fetch http://archive.debian.org/debian-securty/dists/lenny/updates/main/source/Sources  404 Not Found [IP: 130.89.148.13 80]</code></p>
  
  <p>First I get KEYEXPIRED error (with NO_PUBKEY but that's not the point now) then i tried this solution:</p>
  
  <p><a href="http://community.aegirproject.org/node/757/revisions/2077/view" rel="nofollow">http://community.aegirproject.org/node/757/revisions/2077/view</a></p>
  
  <p>(but I am not sure I did everything correctly)</p>
  
  <p><code>W: There is no public key available for the following key IDs:
  4D270D06F42584E6
  W: GPG error: http://archive.debian.org lenny/updates Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9AA38DCD55BE302B
  W: GPG error: http://archive.debian.org lenny/volatile Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY DFD993306D849617
  W: Failed to fetch http://archive.debian.org/debian-securty/dists/lenny/updates/main/source/Sources  404 Not Found [IP: 130.89.148.13 80]
  </code></p>
  
  <p>Then I get NO_PUBKEY error and I tried this solution and I turned back my initial problem :(</p>
  
  <p><code>sudo apt-key adv --recv-keys --keyserver keys.gnupg.net</code> (8 digit key)</p>
  
  <p>could you help me?</p>