1PGPVERIFY(1)              InterNetNews Documentation              PGPVERIFY(1)
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NAME

6       pgpverify - Cryptographically verify Usenet control messages
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SYNOPSIS

9       pgpverify [--findid=string] [--test] < message
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DESCRIPTION

12       The pgpverify program reads (on standard input) a Usenet control
13       message that has been cryptographically signed using the signcontrol
14       program (or some other program that produces a compatible format).
15       pgpverify then uses a PGP implementation to determine who signed the
16       control message.  If the control message has a valid signature,
17       pgpverify prints (to stdout) the user ID of the key that signed the
18       message.  Otherwise, it exits with a non-zero exit status.
19
20       If pgpverify is installed as part of INN, it uses INN's configuration
21       to determine what signature verification program to use, how to log
22       errors, what temporary directory to use, and what keyring to use.
23       Otherwise, all of those parameters can be set by editing the beginning
24       of this script.
25
26       By default, when running as part of INN, pgpverify expects the PGP key
27       ring to be found in pathetc/pgp (as either pubring.pgp or pubring.gpg
28       depending on whether PGP or GnuPG is used to verify signatures).  If
29       that directory doesn't exist, it will fall back on using the default
30       key ring, which is in a .pgp or .gnupg subdirectory of the running
31       user's home directory.
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33       INN, when using GnuPG, configures pgpverify to use gpg or gpgv, which
34       by default expects keys to be in a keyring named trustedkeys.gpg, since
35       it doesn't implement trust checking directly.  pgpverify uses that file
36       if present but falls back to pubring.gpg if it's not found.  This
37       bypasses the trust model for checking keys, but is compatible with the
38       way that pgpverify used to behave.  Of course, if a keyring is found in
39       pathetc/pgp or configured at the top of the script, that overrides all
40       of this behavior.
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42       Note that a few Usenet hierarchies still send control articles signed
43       with old PGP keys using a weak hash algorithm (MD5).  Modern versions
44       of GnuPG (2.1.0+) no longer validate such signatures, so you should use
45       GnuPG 1.x or 2.0.x if you need verifying such control articles.
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OPTIONS

48       --findid=string
49           The --findid flag causes pgpverify to explicitly search for string
50           in the output from PGP's analysis of the message.  This option is
51           useful when several UIDs are defined on a single PGP key, and the
52           caller to pgpverify needs checking whether a given one is defined
53           on this key.  In case the signature is valid but does not contain
54           string, pgpverify exits with exit status 4.
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56       --test
57           The --test flag causes pgpverify to print out the input that it is
58           passing to PGP (which is a reconstructed version of the input that
59           supposedly created the control message) as well as the output from
60           PGP's analysis of the message.
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EXIT STATUS

63       pgpverify may exit with the following statuses:
64
65       0   The control message had a good PGP signature.
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67       1   The control message had no PGP signature.
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69       2   The control message had an unknown PGP signature.
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71       3   The control message had a bad PGP signature.
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73       4   The control message had a good PGP signature but the argument given
74           to the --findid flag had non been found in the output from PGP's
75           analysis of the message.
76
77       255 A problem occurred not directly related to PGP analysis of
78           signature.
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ENVIRONMENT

81       pgpverify does not modify or otherwise alter the environment before
82       invoking the pgp, gpgv or gpg program.  It is the responsibility of the
83       person who installs pgpverify to ensure that when pgp, gpgv or gpg
84       runs, it has the ability to locate and read a PGP key file that
85       contains the PGP public keys for the appropriate Usenet hierarchy
86       administrators.  pgpverify can be pointed to an appropriate key ring by
87       editing variables at the beginning of this script.
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NOTES

90       Historically, Usenet news server administrators have configured their
91       news servers to automatically honor Usenet control messages based on
92       the originator of the control messages and the hierarchies for which
93       the control messages applied.  For example, in the past, David Lawrence
94       always issued control messages for the "Big 8" hierarchies (comp,
95       humanities, misc, news, rec, sci, soc, talk).  Usenet news
96       administrators would configure their news server software to
97       automatically honor newgroup and rmgroup control messages that
98       originated from David Lawrence and applied to any of the Big 8
99       hierarchies.
100
101       Unfortunately, Usenet news articles (including control messages) are
102       notoriously easy to forge.  Soon, malicious users realized they could
103       create or remove (at least temporarily) any Big 8 newsgroup they wanted
104       by simply forging an appropriate control message in David Lawrence's
105       name.  As Usenet became more widely used, forgeries became more common.
106
107       The pgpverify program was designed to allow Usenet news administrators
108       to configure their servers to cryptographically verify control messages
109       before automatically acting on them.  Under the pgpverify system, a
110       Usenet hierarchy maintainer creates a PGP public/private key pair and
111       disseminates the public key.  Whenever the hierarchy maintainer issues
112       a control message, he uses the signcontrol program to sign the control
113       message with the PGP private key.  Usenet news administrators configure
114       their news servers to run the pgpverify program on the appropriate
115       control messages, and take action based on the PGP key User ID that
116       signed the control message, not the name and address that appear in the
117       control message's From: or Sender: headers.
118
119       Thus, appropriate use of the signcontrol and pgpverify programs
120       essentially eliminates the possibility of malicious users forging
121       Usenet control messages that sites will act upon, as such users would
122       have to obtain the PGP private key in order to forge a control message
123       that would pass the cryptographic verification step.  If the hierarchy
124       administrators properly protect their PGP private keys, the only way a
125       malicious user could forge a validly-signed control message would be by
126       breaking the public key encryption algorithm, which (at least at this
127       time) is believed to be prohibitively difficult for PGP keys of a
128       sufficient bit length.
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HISTORY

131       pgpverify was written by David C Lawrence <tale@isc.org>.  Manual page
132       provided by James Ralston.  It is currently maintained by Russ Allbery
133       <eagle@eyrie.org>.
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136       David Lawrence wrote:  "Our lawyer told me to include the following.
137       The upshot of it is that you can use the software for free as much as
138       you like."
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140       Copyright (c) 1996 UUNET Technologies, Inc.  All rights reserved.
141
142       Redistribution and use in source and binary forms, with or without
143       modification, are permitted provided that the following conditions are
144       met:
145
146       1.  Redistributions of source code must retain the above copyright
147           notice, this list of conditions and the following disclaimer.
148
149       2.  Redistributions in binary form must reproduce the above copyright
150           notice, this list of conditions and the following disclaimer in the
151           documentation and/or other materials provided with the
152           distribution.
153
154       3.  All advertising materials mentioning features or use of this
155           software must display the following acknowledgement:
156
157             This product includes software developed by UUNET Technologies, Inc.
158
159       4.  The name of UUNET Technologies ("UUNET") may not be used to endorse
160           or promote products derived from this software without specific
161           prior written permission.
162
163       THIS SOFTWARE IS PROVIDED BY UUNET "AS IS" AND ANY EXPRESS OR IMPLIED
164       WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
165       MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
166       IN NO EVENT SHALL UUNET BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
167       SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
168       LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
169       DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
170       THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
171       (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
172       OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
173

SEE ALSO

175       gpg(1), gpgv(1), pgp(1).
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177       <https://ftp.isc.org/pub/pgpcontrol/> is where the most recent versions
178       of signcontrol and pgpverify live, along with PGP public keys used for
179       hierarchy administration.
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183INN 2.7.0                         2022-07-10                      PGPVERIFY(1)
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