PGPVERIFY(1) InterNetNews Documentation PGPVERIFY(1)
pgpverify - Cryptographically verify Usenet control messages
pgpverify [-test] < message
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
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.
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.
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-
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.
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.
<ftp://ftp.isc.org/pub/pgpcontrol/> is where the most recent versions
of signcontrol and pgpverify live, along with PGP public keys used for
pgpverify was written by David C Lawrence <email@example.com>. Manual page
provided by James Ralston. It is currently maintained by Russ Allbery
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
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
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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