pgpverify



PGPVERIFY(1)              InterNetNews Documentation              PGPVERIFY(1)




NAME

       pgpverify - Cryptographically verify Usenet control messages


SYNOPSIS

       pgpverify [-test] < message


DESCRIPTION

       The pgpverify program reads (on standard input) a Usenet control mes-
       sage that has been cryptographically signed using the signcontrol pro-
       gram (or some other program that produces a compatible format).
       pgpverify then uses a PGP implementation to determine who signed the
       control message.  If the control message has a valid signature, pgpver-
       ify prints (to stdout) the user ID of the key that signed the message.
       Otherwise, it exits with a non-zero exit status.

       If pgpverify is installed as part of INN, it uses INN’s configuration
       to determine what signature verification program to use, how to log
       errors, what temporary directory to use, and what keyring to use.  Oth-
       erwise, all of those parameters can be set by editing the beginning of
       this script.

       By default, when running as part of INN, pgpverify expects the PGP key
       ring to be found in pathetc/pgp (as either pubring.pgp or pubring.gpg
       depending on whether PGP or GnuPG is used to verify signatures).  If
       that directory doesn’t exist, it will fall back on using the default
       key ring, which is in a .pgp or .gnupg subdirectory of the running
       user’s home directory.


OPTIONS

       The -test flag causes pgpverify to print out the input that it is pass-
       ing to PGP (which is a reconstructed version of the input that suppos-
       edly created the control message) as well as the output from PGP’s
       analysis of the message.


EXIT STATUS

       pgpverify may exit with the following statuses:

       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 signa-
            ture.


ENVIRONMENT

       pgpverify does not modify or otherwise alter the environment before
       invoking the pgp or gpgv program.  It is the responsibility of the per-
       son who installs pgpverify to ensure that when pgp or gpgv 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.
       pgpverify can be pointed to an appropriate key ring by editing vari-
       ables at the beginning of this script.


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 Lawrence
       always issued control messages for the "Big 8" hierarchies (comp,
       humanities, misc, news, rec, sci, soc, talk).  Usenet news administra-
       tors 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 con-
       trol 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 con-
       trol message’s From or Sender headers.

       Thus, appropriate use of the signcontrol and pgpverify programs essen-
       tially 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 public key encryption algorithm, which (at least at this
       time) is believed to be prohibitively difficult for PGP keys of a suf-
       ficient bit length.


SEE ALSO

       gpgv(1), pgp(1)

       <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.


HISTORY

       pgpverify was written by David C Lawrence <tale@isc.org>.  Manual page
       provided by James Ralston.  It is currently maintained by Russ Allbery
       <rra@stanford.edu>.


COPYRIGHT AND LICENSE

       David Lawrence wrote:  "Our lawyer told me to include the following.
       The upshot of it is that you can use the software for free as much as
       you like."

       Copyright (c) 1996 UUNET Technologies, Inc.  All rights reserved.

       Redistribution and use in source and binary forms, with or without mod-
       ification, are permitted provided that the following conditions are
       met:

       1. Redistributions of source code must retain the above copyright
          notice, this list of conditions and the following disclaimer.

       2. Redistributions in binary form must reproduce the above copyright
          notice, this list of conditions and the following disclaimer in the
          documentation and/or other materials provided with the distribution.

       3. All advertising materials mentioning features or use of this soft-
          ware must display the following acknowledgement:

            This product includes software developed by UUNET Technologies, Inc.

       4. The name of UUNET Technologies ("UUNET") may not be used to endorse
          or promote products derived from this software without specific
          prior written permission.

       THIS SOFTWARE IS PROVIDED BY UUNET "AS IS" AND ANY EXPRESS OR IMPLIED
       WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
       MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
       IN NO EVENT SHALL UUNET BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
       SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIM-
       ITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
       DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
       THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
       (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
       OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.



INN 2.4.1                         2004-01-11                      PGPVERIFY(1)

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