title: OpenPGP Signing
body: <p>I'm reading RFC4880 in an attempt to produce an implementatdion of a subset
  of OpenPGP (RSA signatures) using <a href="http://phpseclib.sourceforge.net/" rel="nofollow noreferrer">http://phpseclib.sourceforge.net/</a>.  I 
  have the publickey and compression-literal-signature packets
   parsed out.  I
  can extract n and e and feed them to Crypt_RSA to construct a verifier.  I 
  tell it I'm using sha256.  It then needs a "message" and a "
  signature" 
  parametre.  I get the signature data out of the signature packet no problem.
  The question I have is: what is "message"?  According to sec
  tion 5.2.4 it's
  some combination of the literal data packet(s?) (their bodies or the whole 
  packet?) and the "hashed" subpackets.  Do I just concat all
  the data packets
  and the hashed packets together in the order they appear?</p>