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

6       pgpverify - Cryptographically verify Usenet control messages
7

SYNOPSIS

9       pgpverify [--findid=string] [--test] < message
10

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.
32
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.
41

OPTIONS

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

EXIT STATUS

58       pgpverify may exit with the following statuses:
59
60       0   The control message had a good PGP signature.
61
62       1   The control message had no PGP signature.
63
64       2   The control message had an unknown PGP signature.
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66       3   The control message had a bad PGP signature.
67
68       4   The control message had a good PGP signature but the argument given
69           to the --findid flag had non been found in the output from PGP's
70           analysis of the message.
71
72       255 A problem occurred not directly related to PGP analysis of
73           signature.
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ENVIRONMENT

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

NOTES

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

HISTORY

126       pgpverify was written by David C Lawrence <tale@isc.org>.  Manual page
127       provided by James Ralston.  It is currently maintained by Russ Allbery
128       <eagle@eyrie.org>.
129
131       David Lawrence wrote:  "Our lawyer told me to include the following.
132       The upshot of it is that you can use the software for free as much as
133       you like."
134
135       Copyright (c) 1996 UUNET Technologies, Inc.  All rights reserved.
136
137       Redistribution and use in source and binary forms, with or without
138       modification, are permitted provided that the following conditions are
139       met:
140
141       1.  Redistributions of source code must retain the above copyright
142           notice, this list of conditions and the following disclaimer.
143
144       2.  Redistributions in binary form must reproduce the above copyright
145           notice, this list of conditions and the following disclaimer in the
146           documentation and/or other materials provided with the
147           distribution.
148
149       3.  All advertising materials mentioning features or use of this
150           software must display the following acknowledgement:
151
152             This product includes software developed by UUNET Technologies, Inc.
153
154       4.  The name of UUNET Technologies ("UUNET") may not be used to endorse
155           or promote products derived from this software without specific
156           prior written permission.
157
158       THIS SOFTWARE IS PROVIDED BY UUNET "AS IS" AND ANY EXPRESS OR IMPLIED
159       WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
160       MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
161       IN NO EVENT SHALL UUNET BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
162       SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
163       LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
164       DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
165       THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
166       (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
167       OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
168

SEE ALSO

170       gpg(1), gpgv(1), pgp(1).
171
172       <https://ftp.isc.org/pub/pgpcontrol/> is where the most recent versions
173       of signcontrol and pgpverify live, along with PGP public keys used for
174       hierarchy administration.
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178INN 2.6.4                         2021-01-21                      PGPVERIFY(1)
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