pgpverify  -  cryptographically verify Usenet control mes­
       sages


SYNOPSIS

       pgpverify [ -test ]


DESCRIPTION

       The pgpverify program reads (on standard input)  a  Usenet
       control  message  that  has  been cryptographically signed
       using the signcontrol program.  pgpverify  then  uses  the
       pgp  program  to determine who signed the control message.
       If the control message was validly signed, pgpverify  out­
       puts (to stdout) the User ID of the key ID that signed the
       message.


OPTIONS

       The ``-test'' flag causes pgpverify to print out the input
       it  is passing to pgp (which is a reconstructed version of
       the input that supposedly created the control message)  as
       well as the output of pgp's analysis of the message.


EXIT STATUS

       pgpverify returns the follow exit statuses for the follow­
       ing cases:

       0      The control message had a good PGP signature.

       1      The control message had no PGP signature.

       2      The control message had an unknown PGP signature.

       3      The control message had a bad PGP signature.

       255    A problem occurred  not  directly  related  to  PGP
              analysis of signature.


AUTHOR

       David C Lawrence <tale@isc.org>


ENVIRONMENT

       pgpverify  does not modify or otherwise alter the environ­
       ment before invoking the pgp program.  It is the responsi­
       bility of the person who installs pgpverify to ensure that
       when pgp runs, it has the ability to locate and read a PGP
       key  file that contains the PGP public keys for the appro­
       priate Usenet hierarchy administrators.


SEE ALSO

       pgp(1)


NOTES

       Historically,  Usenet  news  server  administrators   have

       Usenet control messages based on  the  originator  of  the
       control messages and the hierarchies for which the control
       messages applied.  For  example,  in  the  past,  David  C
       Lawrence  <tale@uunet.uu.net>  always  issued control mes­
       sages for the "Big 8" hierarchies (comp, humanities, misc,
       news,  rec,  sci,  soc, talk).  Usenet news administrators
       would configure their news server  software  to  automati­
       cally  honor  newgroup  and  rmgroup control messages that
       originated from David Lawrence and applied to any  of  the
       Big 8 hierarchies.

       Unfortunately,  Usenet  news  articles  (including control
       messages) are notoriously easy to forge.  Soon,  malicious
       users  realized they could create or remove (at least tem­
       porarily) any Big 8 newsgroup they wanted by simply  forg­
       ing  an  appropriate  control  message in David Lawrence's
       name.  As Usenet became more widely used, forgeries became
       more common.

       The  pgpverify  program  was designed to allow Usenet news
       administrators to configure their servers to cryptographi­
       cally  verify control messages before automatically acting
       on them.  Under the pgpverify system, a  Usenet  hierarchy
       maintainer  creates a PGP public/private key pair and dis­
       seminates the public key.  Whenever  the  hierarchy  main­
       tainer  issues  a control message, he uses the signcontrol
       program to sign the control message with the  PGP  private
       key.   Usenet  news  administrators  configure  their news
       servers to run the pgpverify program  on  the  appropriate
       control  messages,  and  take  action based on the PGP key
       User ID that signed the control message, not the name  and
       address  that  appear  in  the  control  message's From or
       Sender headers.

       Thus, using the signcontrol and pgpverify programs  appro­
       priately  essentially  eliminates the possibility of mali­
       cious users forging Usenet  control  messages  that  sites
       will  act upon, as such users would have to obtain the PGP
       private key in order to forge a control message that would
       pass  the cryptographic verification step.  If the hierar­
       chy administrators  properly  protect  their  PGP  private
       keys, the only way a malicious user could forge a validly-
       signed control  message  would  be  by  breaking  the  RSA
       encryption  algorithm,  which  (at  least at this time) is
       believed to be an NP-complete problem.  If this is  indeed
       the case, discovering the PGP private key based on the PGP
       public key is computationally impossible for PGP keys of a
       sufficient bit length.

       <URL:ftp://ftp.isc.org/pub/pgpcontrol/>  is where the most
       recent versions of signcontrol and pgpverify  live,  along
       with PGP public keys used for hierarchy administration.


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