1PGPVERIFY(1) InterNetNews Documentation PGPVERIFY(1)
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6 pgpverify - Cryptographically verify Usenet control messages
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9 pgpverify [-test] < message
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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 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 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 INN, when using GnuPG, configures pgpverify to use gpgv, which by
34 default expects keys to be in a keyring named trustedkeys.gpg, since it
35 doesn't implement trust checking directly. pgpverify uses that file if
36 present but falls back to pubring.gpg if it's not found. This bypasses
37 the trust model for checking keys, but is compatible with the way that
38 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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43 The -test flag causes pgpverify to print out the input that it is
44 passing to PGP (which is a reconstructed version of the input that
45 supposedly created the control message) as well as the output from
46 PGP's analysis of the message.
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49 pgpverify may exit with the following statuses:
50 0 The control message had a good PGP signature.
52 1 The control message had no PGP signature.
54 2 The control message had an unknown PGP signature.
56 3 The control message had a bad PGP signature.
58 255 A problem occurred not directly related to PGP analysis of
60 signature.
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63 pgpverify does not modify or otherwise alter the environment before
64 invoking the pgp or gpgv program. It is the responsibility of the
65 person who installs pgpverify to ensure that when pgp or gpgv runs, it
66 has the ability to locate and read a PGP key file that contains the PGP
67 public keys for the appropriate Usenet hierarchy administrators.
68 pgpverify can be pointed to an appropriate key ring by editing
69 variables at the beginning of this script.
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72 Historically, Usenet news server administrators have configured their
73 news servers to automatically honor Usenet control messages based on
74 the originator of the control messages and the hierarchies for which
75 the control messages applied. For example, in the past, David Lawrence
76 always issued control messages for the "Big 8" hierarchies (comp,
77 humanities, misc, news, rec, sci, soc, talk). Usenet news
78 administrators would configure their news server software to
79 automatically honor newgroup and rmgroup control messages that
80 originated from David Lawrence and applied to any of the Big 8
81 hierarchies.
82 Unfortunately, Usenet news articles (including control messages) are
84 notoriously easy to forge. Soon, malicious users realized they could
85 create or remove (at least temporarily) any Big 8 newsgroup they wanted
86 by simply forging an appropriate control message in David Lawrence's
87 name. As Usenet became more widely used, forgeries became more common.
88 The pgpverify program was designed to allow Usenet news administrators
90 to configure their servers to cryptographically verify control messages
91 before automatically acting on them. Under the pgpverify system, a
92 Usenet hierarchy maintainer creates a PGP public/private key pair and
93 disseminates the public key. Whenever the hierarchy maintainer issues
94 a control message, he uses the signcontrol program to sign the control
95 message with the PGP private key. Usenet news administrators configure
96 their news servers to run the pgpverify program on the appropriate
97 control messages, and take action based on the PGP key User ID that
98 signed the control message, not the name and address that appear in the
99 control message's From: or Sender: headers.
100 Thus, appropriate use of the signcontrol and pgpverify programs
102 essentially eliminates the possibility of malicious users forging
103 Usenet control messages that sites will act upon, as such users would
104 have to obtain the PGP private key in order to forge a control message
105 that would pass the cryptographic verification step. If the hierarchy
106 administrators properly protect their PGP private keys, the only way a
107 malicious user could forge a validly-signed control message would be by
108 breaking the public key encryption algorithm, which (at least at this
109 time) is believed to be prohibitively difficult for PGP keys of a
110 sufficient bit length.
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113 pgpverify was written by David C Lawrence <tale@isc.org>. Manual page
114 provided by James Ralston. It is currently maintained by Russ Allbery
115 <rra@stanford.edu>.
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118 David Lawrence wrote: "Our lawyer told me to include the following.
119 The upshot of it is that you can use the software for free as much as
120 you like."
121 Copyright (c) 1996 UUNET Technologies, Inc. All rights reserved.
123 Redistribution and use in source and binary forms, with or without
125 modification, are permitted provided that the following conditions are
126 met:
127 1. Redistributions of source code must retain the above copyright
129 notice, this list of conditions and the following disclaimer.
130 2. Redistributions in binary form must reproduce the above copyright
132 notice, this list of conditions and the following disclaimer in the
133 documentation and/or other materials provided with the
134 distribution.
135 3. All advertising materials mentioning features or use of this
137 software must display the following acknowledgement:
138 This product includes software developed by UUNET Technologies, Inc.
140 4. The name of UUNET Technologies ("UUNET") may not be used to endorse
142 or promote products derived from this software without specific
143 prior written permission.
144 THIS SOFTWARE IS PROVIDED BY UUNET "AS IS" AND ANY EXPRESS OR IMPLIED
146 WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
147 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
148 IN NO EVENT SHALL UUNET BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
149 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
150 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
151 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
152 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
153 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
154 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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157 gpgv(1), pgp(1).
158 <ftp://ftp.isc.org/pub/pgpcontrol/> is where the most recent versions
160 of signcontrol and pgpverify live, along with PGP public keys used for
161 hierarchy administration.
162INN 2.5.2 2009-05-21 PGPVERIFY(1)