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1 | \input texinfo @c -*-texinfo-*- |
2 | ||
3 | @setfilename ../info/pgg | |
4 | ||
5 | @set VERSION 0.1 | |
6 | ||
7 | ||
8 | @copying | |
b223e22d | 9 | This file describes PGG, an Emacs interface to various PGP implementations. |
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11 | Copyright @copyright{} 2003, 2004, 2005, 2006 Free Software Foundation, Inc. |
12 | Copyright @copyright{} 2001 Daiki Ueno. | |
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13 | |
14 | @quotation | |
15 | Permission is granted to copy, distribute and/or modify this document | |
678e7c71 | 16 | under the terms of the GNU Free Documentation License, Version 1.2 or |
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17 | any later version published by the Free Software Foundation; with no |
18 | Invariant Sections, with no Front-Cover Texts, and with no Back-Cover | |
19 | Texts. A copy of the license is included in the section entitled ``GNU | |
20 | Free Documentation License''. | |
21 | @end quotation | |
22 | @end copying | |
23 | ||
24 | @dircategory Emacs | |
25 | @direntry | |
26 | * PGG: (pgg). Emacs interface to various PGP implementations. | |
27 | @end direntry | |
28 | ||
29 | @settitle PGG @value{VERSION} | |
30 | ||
31 | ||
32 | @titlepage | |
33 | @title PGG | |
34 | ||
35 | @author by Daiki Ueno | |
36 | @page | |
37 | ||
38 | @vskip 0pt plus 1filll | |
39 | @insertcopying | |
40 | @end titlepage | |
41 | @page | |
42 | ||
43 | @node Top | |
44 | @top PGG | |
45 | This manual describes PGG. PGG is an interface library between Emacs | |
46 | and various tools for secure communication. PGG also provides a simple | |
47 | user interface to encrypt, decrypt, sign, and verify MIME messages. | |
48 | ||
49 | @menu | |
50 | * Overview:: What PGG is. | |
51 | * Prerequisites:: Complicated stuff you may have to do. | |
52 | * How to use:: Getting started quickly. | |
53 | * Architecture:: | |
54 | * Parsing OpenPGP packets:: | |
55 | * Function Index:: | |
56 | * Variable Index:: | |
57 | @end menu | |
58 | ||
59 | @node Overview | |
60 | @chapter Overview | |
61 | ||
62 | PGG is an interface library between Emacs and various tools for secure | |
63 | communication. Even though Mailcrypt has similar feature, it does not | |
64 | deal with detached PGP messages, normally used in PGP/MIME | |
65 | infrastructure. This was the main reason why I wrote the new library. | |
66 | ||
67 | PGP/MIME is an application of MIME Object Security Services (RFC1848). | |
68 | The standard is documented in RFC2015. | |
69 | ||
70 | @node Prerequisites | |
71 | @chapter Prerequisites | |
72 | ||
73 | PGG requires at least one implementation of privacy guard system. | |
74 | This document assumes that you have already obtained and installed them | |
75 | and that you are familiar with its basic functions. | |
76 | ||
77 | By default, PGG uses GnuPG, but Pretty Good Privacy version 2 or version | |
78 | 5 are also supported. If you are new to such a system, I recommend that | |
79 | you should look over the GNU Privacy Handbook (GPH) which is available | |
80 | at @uref{http://www.gnupg.org/gph/}. | |
81 | ||
82 | @node How to use | |
83 | @chapter How to use | |
84 | ||
85 | The toplevel interface of this library is quite simple, and only | |
86 | intended to use with public-key cryptographic operation. | |
87 | ||
88 | To use PGG, evaluate following expression at the beginning of your | |
89 | application program. | |
90 | ||
91 | @lisp | |
92 | (require 'pgg) | |
93 | @end lisp | |
94 | ||
95 | If you want to check existence of pgg.el at runtime, instead you can | |
96 | list autoload setting for desired functions as follows. | |
97 | ||
98 | @lisp | |
99 | (autoload 'pgg-encrypt-region "pgg" | |
100 | "Encrypt the current region." t) | |
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101 | (autoload 'pgg-encrypt-symmetric-region "pgg" |
102 | "Encrypt the current region with symmetric algorithm." t) | |
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103 | (autoload 'pgg-decrypt-region "pgg" |
104 | "Decrypt the current region." t) | |
105 | (autoload 'pgg-sign-region "pgg" | |
106 | "Sign the current region." t) | |
107 | (autoload 'pgg-verify-region "pgg" | |
108 | "Verify the current region." t) | |
109 | (autoload 'pgg-insert-key "pgg" | |
110 | "Insert the ASCII armored public key." t) | |
111 | (autoload 'pgg-snarf-keys-region "pgg" | |
112 | "Import public keys in the current region." t) | |
113 | @end lisp | |
114 | ||
115 | @menu | |
116 | * User Commands:: | |
117 | * Selecting an implementation:: | |
118 | * Caching passphrase:: | |
119 | * Default user identity:: | |
120 | @end menu | |
121 | ||
122 | @node User Commands | |
123 | @section User Commands | |
124 | ||
125 | At this time you can use some cryptographic commands. The behavior of | |
126 | these commands relies on a fashion of invocation because they are also | |
127 | intended to be used as library functions. In case you don't have the | |
128 | signer's public key, for example, the function @code{pgg-verify-region} | |
129 | fails immediately, but if the function had been called interactively, it | |
130 | would ask you to retrieve the signer's public key from the server. | |
131 | ||
98e330e6 | 132 | @deffn Command pgg-encrypt-region start end recipients &optional sign passphrase |
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133 | Encrypt the current region between @var{start} and @var{end} for |
134 | @var{recipients}. When the function were called interactively, you | |
135 | would be asked about the recipients. | |
136 | ||
137 | If encryption is successful, it replaces the current region contents (in | |
138 | the accessible portion) with the resulting data. | |
139 | ||
f4dd4ae8 | 140 | If optional argument @var{sign} is non-@code{nil}, the function is |
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141 | request to do a combined sign and encrypt. This currently is |
142 | confirmed to work with GnuPG, but might not work with PGP or PGP5. | |
143 | ||
144 | If optional @var{passphrase} is @code{nil}, the passphrase will be | |
145 | obtained from the passphrase cache or user. | |
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146 | @end deffn |
147 | ||
98e330e6 | 148 | @deffn Command pgg-encrypt-symmetric-region &optional start end passphrase |
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149 | Encrypt the current region between @var{start} and @var{end} using a |
150 | symmetric cipher. After invocation you are asked for a passphrase. | |
151 | ||
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152 | If optional @var{passphrase} is @code{nil}, the passphrase will be |
153 | obtained from the passphrase cache or user. | |
154 | ||
155 | symmetric-cipher encryption is currently only implemented for GnuPG. | |
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156 | @end deffn |
157 | ||
98e330e6 | 158 | @deffn Command pgg-decrypt-region start end &optional passphrase |
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159 | Decrypt the current region between @var{start} and @var{end}. If |
160 | decryption is successful, it replaces the current region contents (in | |
161 | the accessible portion) with the resulting data. | |
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162 | |
163 | If optional @var{passphrase} is @code{nil}, the passphrase will be | |
164 | obtained from the passphrase cache or user. | |
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165 | @end deffn |
166 | ||
98e330e6 | 167 | @deffn Command pgg-sign-region start end &optional cleartext passphrase |
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168 | Make the signature from text between @var{start} and @var{end}. If the |
169 | optional third argument @var{cleartext} is non-@code{nil}, or the | |
170 | function is called interactively, it does not create a detached | |
171 | signature. In such a case, it replaces the current region contents (in | |
172 | the accessible portion) with the resulting data. | |
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173 | |
174 | If optional @var{passphrase} is @code{nil}, the passphrase will be | |
175 | obtained from the passphrase cache or user. | |
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176 | @end deffn |
177 | ||
178 | @deffn Command pgg-verify-region start end &optional signature fetch | |
179 | Verify the current region between @var{start} and @var{end}. If the | |
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180 | optional third argument @var{signature} is non-@code{nil}, it is treated |
181 | as the detached signature file of the current region. | |
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182 | |
183 | If the optional 4th argument @var{fetch} is non-@code{nil}, or the | |
184 | function is called interactively, we attempt to fetch the signer's | |
185 | public key from the key server. | |
186 | @end deffn | |
187 | ||
188 | @deffn Command pgg-insert-key | |
189 | Retrieve the user's public key and insert it as ASCII-armored format. | |
190 | @end deffn | |
191 | ||
192 | @deffn Command pgg-snarf-keys-region start end | |
193 | Collect public keys in the current region between @var{start} and | |
194 | @var{end}, and add them into the user's keyring. | |
195 | @end deffn | |
196 | ||
197 | @node Selecting an implementation | |
198 | @section Selecting an implementation | |
199 | ||
200 | Since PGP has a long history and there are a number of PGP | |
201 | implementations available today, the function which each one has differs | |
202 | considerably. For example, if you are using GnuPG, you know you can | |
203 | select cipher algorithm from 3DES, CAST5, BLOWFISH, and so on, but on | |
204 | the other hand the version 2 of PGP only supports IDEA. | |
205 | ||
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206 | Which implementation is used is controlled by the @code{pgg-scheme} |
207 | variable. If it is @code{nil} (the default), the value of the | |
208 | @code{pgg-default-scheme} variable will be used instead. | |
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209 | |
210 | @defvar pgg-scheme | |
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211 | Force specify the scheme of PGP implementation. The value can be set to |
212 | @code{gpg}, @code{pgp}, and @code{pgp5}. The default is @code{nil}. | |
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213 | @end defvar |
214 | ||
215 | @defvar pgg-default-scheme | |
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216 | The default scheme of PGP implementation. The value should be one of |
217 | @code{gpg}, @code{pgp}, and @code{pgp5}. The default is @code{gpg}. | |
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218 | @end defvar |
219 | ||
220 | @node Caching passphrase | |
221 | @section Caching passphrase | |
222 | ||
223 | PGG provides a simple passphrase caching mechanism. If you want to | |
224 | arrange the interaction, set the variable @code{pgg-read-passphrase}. | |
225 | ||
226 | @defvar pgg-cache-passphrase | |
227 | If non-@code{nil}, store passphrases. The default value of this | |
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228 | variable is @code{t}. If you are worried about security issues, |
229 | however, you could stop the caching of passphrases by setting this | |
230 | variable to @code{nil}. | |
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231 | @end defvar |
232 | ||
233 | @defvar pgg-passphrase-cache-expiry | |
234 | Elapsed time for expiration in seconds. | |
235 | @end defvar | |
236 | ||
237 | @node Default user identity | |
238 | @section Default user identity | |
239 | ||
240 | The PGP implementation is usually able to select the proper key to use | |
241 | for signing and decryption, but if you have more than one key, you may | |
242 | need to specify the key id to use. | |
243 | ||
244 | @defvar pgg-default-user-id | |
245 | User ID of your default identity. It defaults to the value returned | |
246 | by @samp{(user-login-name)}. You can customize this variable. | |
247 | @end defvar | |
248 | ||
249 | @defvar pgg-gpg-user-id | |
250 | User ID of the GnuPG default identity. It defaults to @samp{nil}. | |
251 | This overrides @samp{pgg-default-user-id}. You can customize this | |
252 | variable. | |
253 | @end defvar | |
254 | ||
255 | @defvar pgg-pgp-user-id | |
256 | User ID of the PGP 2.x/6.x default identity. It defaults to | |
257 | @samp{nil}. This overrides @samp{pgg-default-user-id}. You can | |
258 | customize this variable. | |
259 | @end defvar | |
260 | ||
261 | @defvar pgg-pgp5-user-id | |
262 | User ID of the PGP 5.x default identity. It defaults to @samp{nil}. | |
263 | This overrides @samp{pgg-default-user-id}. You can customize this | |
264 | variable. | |
265 | @end defvar | |
266 | ||
267 | @node Architecture | |
268 | @chapter Architecture | |
269 | ||
270 | PGG introduces the notion of a "scheme of PGP implementation" (used | |
271 | interchangeably with "scheme" in this document). This term refers to a | |
272 | singleton object wrapped with the luna object system. | |
273 | ||
274 | Since PGG was designed for accessing and developing PGP functionality, | |
275 | the architecture had to be designed not just for interoperability but | |
276 | also for extensiblity. In this chapter we explore the architecture | |
277 | while finding out how to write the PGG backend. | |
278 | ||
279 | @menu | |
280 | * Initializing:: | |
281 | * Backend methods:: | |
282 | * Getting output:: | |
283 | @end menu | |
284 | ||
285 | @node Initializing | |
286 | @section Initializing | |
287 | ||
288 | A scheme must be initialized before it is used. | |
289 | It had better guarantee to keep only one instance of a scheme. | |
290 | ||
291 | The following code is snipped out of @file{pgg-gpg.el}. Once an | |
292 | instance of @code{pgg-gpg} scheme is initialized, it's stored to the | |
293 | variable @code{pgg-scheme-gpg-instance} and will be reused from now on. | |
294 | ||
295 | @lisp | |
296 | (defvar pgg-scheme-gpg-instance nil) | |
297 | ||
298 | (defun pgg-make-scheme-gpg () | |
299 | (or pgg-scheme-gpg-instance | |
300 | (setq pgg-scheme-gpg-instance | |
301 | (luna-make-entity 'pgg-scheme-gpg)))) | |
302 | @end lisp | |
303 | ||
304 | The name of the function must follow the | |
305 | regulation---@code{pgg-make-scheme-} follows the backend name. | |
306 | ||
307 | @node Backend methods | |
308 | @section Backend methods | |
309 | ||
310 | In each backend, these methods must be present. The output of these | |
311 | methods is stored in special buffers (@ref{Getting output}), so that | |
312 | these methods must tell the status of the execution. | |
313 | ||
314 | @deffn Method pgg-scheme-lookup-key scheme string &optional type | |
315 | Return keys associated with @var{string}. If the optional third | |
316 | argument @var{type} is non-@code{nil}, it searches from the secret | |
317 | keyrings. | |
318 | @end deffn | |
319 | ||
98e330e6 | 320 | @deffn Method pgg-scheme-encrypt-region scheme start end recipients &optional sign passphrase |
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322 | @var{recipients}. If @var{sign} is non-@code{nil}, do a combined sign |
323 | and encrypt. If encryption is successful, it returns @code{t}, | |
324 | otherwise @code{nil}. | |
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325 | @end deffn |
326 | ||
98e330e6 | 327 | @deffn Method pgg-scheme-encrypt-symmetric-region scheme start end &optional passphrase |
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328 | Encrypt the current region between @var{start} and @var{end} using a |
329 | symmetric cipher and a passphrases. If encryption is successful, it | |
330 | returns @code{t}, otherwise @code{nil}. This function is currently only | |
331 | implemented for GnuPG. | |
332 | @end deffn | |
333 | ||
98e330e6 | 334 | @deffn Method pgg-scheme-decrypt-region scheme start end &optional passphrase |
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335 | Decrypt the current region between @var{start} and @var{end}. If |
336 | decryption is successful, it returns @code{t}, otherwise @code{nil}. | |
337 | @end deffn | |
338 | ||
98e330e6 | 339 | @deffn Method pgg-scheme-sign-region scheme start end &optional cleartext passphrase |
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340 | Make the signature from text between @var{start} and @var{end}. If the |
341 | optional third argument @var{cleartext} is non-@code{nil}, it does not | |
342 | create a detached signature. If signing is successful, it returns | |
343 | @code{t}, otherwise @code{nil}. | |
344 | @end deffn | |
345 | ||
346 | @deffn Method pgg-scheme-verify-region scheme start end &optional signature | |
347 | Verify the current region between @var{start} and @var{end}. If the | |
348 | optional third argument @var{signature} is non-@code{nil}, it is treated | |
349 | as the detached signature of the current region. If the signature is | |
350 | successfully verified, it returns @code{t}, otherwise @code{nil}. | |
351 | @end deffn | |
352 | ||
353 | @deffn Method pgg-scheme-insert-key scheme | |
354 | Retrieve the user's public key and insert it as ASCII-armored format. | |
355 | On success, it returns @code{t}, otherwise @code{nil}. | |
356 | @end deffn | |
357 | ||
358 | @deffn Method pgg-scheme-snarf-keys-region scheme start end | |
359 | Collect public keys in the current region between @var{start} and | |
360 | @var{end}, and add them into the user's keyring. | |
361 | On success, it returns @code{t}, otherwise @code{nil}. | |
362 | @end deffn | |
363 | ||
364 | @node Getting output | |
365 | @section Getting output | |
366 | ||
367 | The output of the backend methods (@ref{Backend methods}) is stored in | |
368 | special buffers, so that these methods must tell the status of the | |
369 | execution. | |
370 | ||
371 | @defvar pgg-errors-buffer | |
372 | The standard error output of the execution of the PGP command is stored | |
373 | here. | |
374 | @end defvar | |
375 | ||
376 | @defvar pgg-output-buffer | |
377 | The standard output of the execution of the PGP command is stored here. | |
378 | @end defvar | |
379 | ||
380 | @defvar pgg-status-buffer | |
381 | The rest of status information of the execution of the PGP command is | |
382 | stored here. | |
383 | @end defvar | |
384 | ||
385 | @node Parsing OpenPGP packets | |
386 | @chapter Parsing OpenPGP packets | |
387 | ||
388 | The format of OpenPGP messages is maintained in order to publish all | |
389 | necessary information needed to develop interoperable applications. | |
390 | The standard is documented in RFC 2440. | |
391 | ||
392 | PGG has its own parser for the OpenPGP packets. | |
393 | ||
394 | @defun pgg-parse-armor string | |
395 | List the sequence of packets in @var{string}. | |
396 | @end defun | |
397 | ||
398 | @defun pgg-parse-armor-region start end | |
399 | List the sequence of packets in the current region between @var{start} | |
400 | and @var{end}. | |
401 | @end defun | |
402 | ||
403 | @defvar pgg-ignore-packet-checksum | |
404 | If non-@code{nil}, don't check the checksum of the packets. | |
405 | @end defvar | |
406 | ||
407 | @node Function Index | |
408 | @chapter Function Index | |
409 | @printindex fn | |
410 | ||
411 | @node Variable Index | |
412 | @chapter Variable Index | |
413 | @printindex vr | |
414 | ||
415 | @summarycontents | |
416 | @contents | |
417 | @bye | |
418 | ||
419 | @c End: | |
420 | ||
421 | @ignore | |
422 | arch-tag: 0c205838-34b9-41a5-b9d7-49ae57ccac85 | |
423 | @end ignore |