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 message that has been cryptographically signed using the signcontrol
       program (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, pgpverify 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.  Otherwise, 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.

       INN, when using GnuPG, configures pgpverify to use gpgv, which by default expects keys to be in a keyring named trustedkeys.gpg, since it
       doesn't implement trust checking directly.  pgpverify uses that file if present but falls back to pubring.gpg if it's not found.  This
       bypasses the trust model for checking keys, but is compatible with the way that pgpverify used to behave.  Of course, if a keyring is found
       in pathetc/pgp or configured at the top of the script, that overrides all of this behavior.

OPTIONS

       The -test flag causes pgpverify to print out the input that it is passing to PGP (which is a reconstructed version of the input that
       supposedly 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 signature.

ENVIRONMENT

       pgpverify does not modify or otherwise alter the environment before invoking the pgp or gpgv program.  It is the responsibility of the
       person 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
       variables 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
       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, appropriate use of the signcontrol and pgpverify programs 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 public key encryption algorithm, which (at least at
       this time) is believed to be prohibitively difficult for PGP keys of a sufficient bit length.

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 modification, 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 software 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 LIMITED 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.

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.

INN 2.5.3							    2009-05-21							      PGPVERIFY(1)