1PGPVERIFY(1) InterNetNews Documentation PGPVERIFY(1)
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6 pgpverify - Cryptographically verify Usenet control messages
7
9 pgpverify [-test] < message
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12 The pgpverify program reads (on standard input) a Usenet control mes‐
13 sage that has been cryptographically signed using the signcontrol pro‐
14 gram (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, pgpver‐
17 ify prints (to stdout) the user ID of the key that signed the message.
18 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. Oth‐
23 erwise, all of those parameters can be set by editing the beginning of
24 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
34 The -test flag causes pgpverify to print out the input that it is pass‐
35 ing to PGP (which is a reconstructed version of the input that suppos‐
36 edly created the control message) as well as the output from PGP's
37 analysis of the message.
38
40 pgpverify may exit with the following statuses:
41 0 The control message had a good PGP signature.
43 1 The control message had no PGP signature.
45 2 The control message had an unknown PGP signature.
47 3 The control message had a bad PGP signature.
49 255 A problem occurred not directly related to PGP analysis of signa‐
51 ture.
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54 pgpverify does not modify or otherwise alter the environment before
55 invoking the pgp or gpgv program. It is the responsibility of the per‐
56 son who installs pgpverify to ensure that when pgp or gpgv runs, it has
57 the ability to locate and read a PGP key file that contains the PGP
58 public keys for the appropriate Usenet hierarchy administrators.
59 pgpverify can be pointed to an appropriate key ring by editing vari‐
60 ables at the beginning of this script.
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63 Historically, Usenet news server administrators have configured their
64 news servers to automatically honor Usenet control messages based on
65 the originator of the control messages and the hierarchies for which
66 the control messages applied. For example, in the past, David Lawrence
67 always issued control messages for the "Big 8" hierarchies (comp,
68 humanities, misc, news, rec, sci, soc, talk). Usenet news administra‐
69 tors would configure their news server software to automatically honor
70 newgroup and rmgroup control messages that originated from David
71 Lawrence and applied to any of the Big 8 hierarchies.
72 Unfortunately, Usenet news articles (including control messages) are
74 notoriously easy to forge. Soon, malicious users realized they could
75 create or remove (at least temporarily) any Big 8 newsgroup they wanted
76 by simply forging an appropriate control message in David Lawrence's
77 name. As Usenet became more widely used, forgeries became more common.
78 The pgpverify program was designed to allow Usenet news administrators
80 to configure their servers to cryptographically verify control messages
81 before automatically acting on them. Under the pgpverify system, a
82 Usenet hierarchy maintainer creates a PGP public/private key pair and
83 disseminates the public key. Whenever the hierarchy maintainer issues
84 a control message, he uses the signcontrol program to sign the control
85 message with the PGP private key. Usenet news administrators configure
86 their news servers to run the pgpverify program on the appropriate con‐
87 trol messages, and take action based on the PGP key User ID that signed
88 the control message, not the name and address that appear in the con‐
89 trol message's From or Sender headers.
90 Thus, appropriate use of the signcontrol and pgpverify programs essen‐
92 tially eliminates the possibility of malicious users forging Usenet
93 control messages that sites will act upon, as such users would have to
94 obtain the PGP private key in order to forge a control message that
95 would pass the cryptographic verification step. If the hierarchy
96 administrators properly protect their PGP private keys, the only way a
97 malicious user could forge a validly-signed control message would be by
98 breaking the public key encryption algorithm, which (at least at this
99 time) is believed to be prohibitively difficult for PGP keys of a suf‐
100 ficient bit length.
101
103 gpgv(1), pgp(1)
104 <ftp://ftp.isc.org/pub/pgpcontrol/> is where the most recent versions
106 of signcontrol and pgpverify live, along with PGP public keys used for
107 hierarchy administration.
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110 pgpverify was written by David C Lawrence <tale@isc.org>. Manual page
111 provided by James Ralston. It is currently maintained by Russ Allbery
112 <rra@stanford.edu>.
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115 David Lawrence wrote: "Our lawyer told me to include the following.
116 The upshot of it is that you can use the software for free as much as
117 you like."
118 Copyright (c) 1996 UUNET Technologies, Inc. All rights reserved.
120 Redistribution and use in source and binary forms, with or without mod‐
122 ification, are permitted provided that the following conditions are
123 met:
124 1. Redistributions of source code must retain the above copyright
126 notice, this list of conditions and the following disclaimer.
127 2. Redistributions in binary form must reproduce the above copyright
129 notice, this list of conditions and the following disclaimer in the
130 documentation and/or other materials provided with the distribution.
131 3. All advertising materials mentioning features or use of this soft‐
133 ware must display the following acknowledgement:
134 This product includes software developed by UUNET Technologies, Inc.
136 4. The name of UUNET Technologies ("UUNET") may not be used to endorse
138 or promote products derived from this software without specific
139 prior written permission.
140 THIS SOFTWARE IS PROVIDED BY UUNET "AS IS" AND ANY EXPRESS OR IMPLIED
142 WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
143 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
144 IN NO EVENT SHALL UUNET BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
145 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIM‐
146 ITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
147 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
148 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
149 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
150 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
151INN 2.4.1 2004-01-11 PGPVERIFY(1)