NAME

       pgpverify - cryptographically verify Usenet control messages

SYNOPSIS

       pgpverify

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 outputs (to stdout) the User ID of the key ID that signed the message.

OPTIONS

       The pgpverify program takes no options.

EXIT STATUS

       pgpverify returns the follow exit statuses for the following 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  environment  before  invoking  the  pgp
       program.   It  is  the  responsibility 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 appropriate Usenet hierarchy administrators.

SEE ALSO

       pgp(1)

NOTES

       Historically,  Usenet  news  server  administrators  have configured their news servers to
       automatically honor 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 messages for the "Big  8"
       hierarchies   (comp,   humanities,   misc,  news,  rec,  sci,  soc,  talk).   Usenet  news
       administrators would configure their news server software to automatically 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 temporarily)
       any Big 8 newsgroup they wanted by simply forging 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 cryptographically verify control messages before automatically acting on  them.
       Under the pgpverify system, a Usenet hierarchy maintainer creates a PGP public/private key
       pair and disseminates the public key.  Whenever the hierarchy maintainer 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 appropriately essentially eliminates
       the possibility of malicious 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   hierarchy
       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.

                                                                                     pgpverify(8)