1 Introduction
2 ------------
3
4 MoinMessage provides a library for creating, signing, encrypting, decrypting,
5 and verifying PGP/GPG content in Python along with mechanisms for updating
6 MoinMoin Wiki instances with such content such that contributors can be
7 identified from their PGP signatures and such details used to authenticate
8 their contributions.
9
10 Configuring GPG for a Wiki
11 --------------------------
12
13 Initialise a homedir for GPG and configure it using ACL (access control list)
14 properties:
15
16 ./scripts/init_wiki_keyring.sh WIKI WEBUSER
17
18 Here, WIKI should be replaced by the top-level Wiki instance directory, and
19 WEBUSER should be the name of the user under which the Web server operates.
20
21 Note that this script may need re-running after the homedir has been changed
22 by gpg operations as gpg likes to remove permissions from various files.
23
24 To be in any way useful, signing keys must be made available within this
25 homedir so that incoming messages can have their senders verified.
26
27 To see the keys available to you in your own environment:
28
29 gpg --list-keys --with-fingerprint
30
31 The full fingerprints are used when defining a user mapping in the Wiki, and
32 the --with-fingerprint option is used to show them. Otherwise, only the last
33 eight characters of the fingerprints are shown.
34
35 Export the public key used when signing messages from your own environment:
36
37 gpg --armor --output 1C1AAF83.asc --export 1C1AAF83
38
39 Import the key into the Wiki's GPG homedir:
40
41 gpg --homedir wiki/gnupg --import 1C1AAF83.asc
42
43 For the Wiki to receive encrypted data, a key for the Wiki must be created:
44
45 gpg --homedir wiki/gnupg --gen-key
46
47 For the Wiki environment to be able to use the key, password access must be
48 disabled. This can be done by either not specifying a password or by removing
49 it later using the --edit-key option.
50
51 Export the Wiki's key for encrypting messages sent to the Wiki:
52
53 gpg --homedir wiki/gnupg --armor --output 0891463A.asc --export 0891463A
54
55 This exported key can now be imported into your own environment:
56
57 gpg --import 0891463A.asc
58
59 Configuring the Wiki
60 --------------------
61
62 In the Wiki configuration, define the following settings:
63
64 moinmessage_gpg_homedir
65 This sets the path to the homedir initialised above.
66
67 moinmessage_gpg_users_page (optional, default is MoinMessageUserDict)
68 This provides a mapping from key fingerprints to Moin usernames.
69
70 moinmessage_gpg_signing_users_page (optional, default is MoinMessageSigningUserDict)
71 This provides a mapping from Moin usernames to key fingerprints.
72
73 moinmessage_gpg_recipients_page (optional, default is MoinMessageRecipientsDict)
74 This provides a mapping from recipients to remote URLs and key fingerprints.
75
76 moinmessage_reject_messages_without_dates (optional, default is True)
77 This causes messages sent to a Wiki using the PostMessage action to be
78 rejected if date information is missing.
79
80 Fingerprints and Keys
81 ---------------------
82
83 All fingerprints mentioned in the various configuration pages must exclude
84 space characters - that is, the letters and digits must appear together in a
85 continuous block of text - and refer to keys available in the Wiki homedir.
86
87 The Fingerprint-to-Username Mapping
88 -----------------------------------
89
90 The mapping from fingerprints to usernames typically defined by the
91 MoinMessageUserDict page is a WikiDict having the following general format:
92
93 fingerprint:: username
94
95 Each fingerprint corresponds to a key used by a person wanting to send
96 messages to the Wiki to sign such messages.
97
98 Each username must correspond to a registered user in the Wiki.
99
100 The Username-to-Signing Key Mapping
101 -----------------------------------
102
103 The mapping from usernames to fingerprints typically defined by the
104 MoinMessageSigningUserDict page is a WikiDict having the following general
105 format:
106
107 username:: fingerprint
108
109 Each fingerprint corresponds to a key available in the Wiki's GPG homedir
110 generated for the purpose of signing the specified user's messages. Such a key
111 is not the same as one used by a person to send messages to the Wiki since
112 only the public key used to verify such messages should be known to the Wiki.
113
114 The Recipients Mapping
115 ----------------------
116
117 The mapping from recipients to remote URLs and fingerprints typically defined
118 by the MoinMessageRecipientsDict page is a WikiDict having the following
119 general format:
120
121 recipient:: location ... [ fingerprint ]
122
123 Locations are specified as follows:
124
125 type=value
126
127 Where the type is "page", the accompanying value must be a page name.
128
129 Where the type is "url", the accompanying value must be a URL that must itself
130 refer to a resource that can accept MoinMessage content.
131
132 Where a location of type "url" has been given, a fingerprint must accompany
133 this information in order to encrypt messages sent to the specified resource.
134
135 Each fingerprint corresponds to a key used by the Wiki to encrypt messages and
136 by the remote site (as identified by the URL) to decrypt messages.
137
138 Quick Start: Signing, Encrypting and Sending Messages
139 -----------------------------------------------------
140
141 To send a message signed and encrypted to a resource on localhost:
142
143 python tests/test_send.py 1C1AAF83 0891463A http://localhost/wiki/ShareTest \
144 collection update 'An update to the Wiki.' 'Another update.'
145
146 Here, the first identifier is a reference to the signing key (over which you
147 have complete control), and the second identifier is a reference to the
148 encryption key (which is a public key published for the Wiki).
149
150 This needs password protection to be removed from the secret key in the Web
151 server environment. It also uses a modified trust model when invoking gpg in
152 order to avoid complaints about the identity of the sender during encryption.
153
154 Below, the mechanisms employed are illustrated through the use of the other
155 test programs.
156
157 Signing
158 -------
159
160 Prepare a message signed with a "detached signature" (note that this does not
161 seem to be what gpg calls a detached signature with the --detach-sig option):
162
163 python tests/test_message.py collection update 'An update to the Wiki.' \
164 'Another update.' \
165 | python tests/test_sign.py 1C1AAF83
166
167 The complicated recipe based on the individual operations is as follows:
168
169 python tests/test_message.py collection update 'An update to the Wiki.' \
170 'Another update.' \
171 > test.txt \
172 && cat test.txt \
173 | gpg --armor -u 1C1AAF83 --detach-sig \
174 | python tests/test_sign_wrap.py test.txt
175
176 Encryption
177 ----------
178
179 Prepare a message with an encrypted payload using the above key:
180
181 python tests/test_message.py collection update 'An update to the Wiki.' \
182 'Another update.' \
183 | python tests/test_encrypt.py 0891463A
184
185 The complicated recipe based on the individual operations is as follows:
186
187 python tests/test_message.py collection update 'An update to the Wiki.' \
188 'Another update.' \
189 > test.txt \
190 && cat test.txt \
191 | gpg --armor -r 0891463A --encrypt --trust-model always \
192 | python tests/test_encrypt_wrap.py
193
194 Note that "--trust-model always" is used only to avoid prompting issues.
195
196 Signing and Encrypting
197 ----------------------
198
199 Sign and encrypt a message:
200
201 python tests/test_message.py collection update 'An update to the Wiki.' \
202 'Another update.' \
203 | python tests/test_sign.py 1C1AAF83 \
204 | python tests/test_encrypt.py 0891463A
205
206 The complicated recipe based on the individual operations is as follows:
207
208 python tests/test_message.py collection update 'An update to the Wiki.' \
209 'Another update.' \
210 > test.txt \
211 && cat test.txt \
212 | gpg --armor -u 1C1AAF83 --detach-sig \
213 | python tests/test_sign_wrap.py test.txt \
214 | gpg --armor -r 0891463A --encrypt --trust-model always \
215 | python tests/test_encrypt_wrap.py
216
217 Posting a Message
218 -----------------
219
220 To post a signed and/or encrypted message, output from the above activities
221 can be piped into the following command:
222
223 python tests/test_post.py http://localhost/wiki/ShareTest
224
225 Here, the resource "/wiki/ShareTest" on localhost is presented with the
226 message.
227
228 The Message Format
229 ------------------
230
231 Messages are MIME-encoded and consist of one or more update fragments. Where
232 the "Update-Type" header is present and set to a value of "collection", a
233 multipart message describes as many updates as there are parts. Otherwise,
234 only a single update is described by the message.
235
236 For each update, the "Update-Action" header indicates the action to be taken
237 with the update content. Where it is absent, the content is inserted into the
238 Wiki page specified in the request; where it is present and set to "replace",
239 the content replaces all content on the Wiki page; where it is set to "store",
240 the content is stored in a message store associated with the Wiki page.
241
242 Each update may describe multiple representations of some content by employing
243 a multipart section containing parts for each of the representations.
244 Alternatively, a single message part may describe a single representation.