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c65df279 | 1 | .\" -*-nroff-*- |
2 | .de VS | |
3 | .sp 1 | |
4 | .RS | |
5 | .nf | |
6 | .ft B | |
7 | .. | |
8 | .de VE | |
9 | .ft R | |
10 | .fi | |
11 | .RE | |
12 | .sp 1 | |
13 | .. | |
14 | .ie t \{\ | |
15 | . if \n(.g \{\ | |
16 | . fam P | |
17 | . \} | |
18 | .\} | |
19 | .de hP | |
20 | .IP | |
21 | .ft B | |
22 | \h'-\w'\\$1\ 'u'\\$1\ \c | |
23 | .ft P | |
24 | .. | |
25 | .ie t .ds o \(bu | |
26 | .el .ds o o | |
27 | .TH dsig 1 "30 September 2004" "Straylight/Edgeware" "Catacomb cryptographic library" | |
28 | .SH NAME | |
29 | dsig \- compute and verify signatures on collections of files | |
30 | .SH SYNOPSIS | |
31 | .B dsig | |
32 | .RB [ \-k | |
33 | .IR keyring ] | |
34 | .I command | |
35 | .PP | |
36 | where | |
37 | .I command | |
38 | is one of: | |
39 | .PP | |
40 | .B help | |
41 | .RI [ command ...] | |
42 | .br | |
43 | .B show | |
44 | .RI [ item ...] | |
45 | .br | |
46 | .B sign | |
cd6eca43 | 47 | .RB [ \-0bpqvC ] |
c65df279 | 48 | .RB [ \-c |
49 | .IR comment ] | |
50 | .RB [ \-k | |
51 | .IR tag ] | |
52 | .RB [ \-e | |
53 | .IR expire ] | |
54 | .br | |
55 | \h'8n' | |
56 | .RB [ \-f | |
57 | .IR file ] | |
58 | .RB [ \-o | |
59 | .IR output ] | |
60 | .br | |
61 | .B verify | |
cd6eca43 | 62 | .RB [ \-pqvC ] |
c65df279 | 63 | .RI [ file ] |
64 | .SH DESCRIPTION | |
65 | The | |
66 | .B dsig | |
67 | command signs and verifies signatures on a collection of files. It | |
68 | provides a number of subcommands, by which the various operations may be | |
69 | carried out. | |
70 | .SS "Global options" | |
71 | Before the command name, | |
72 | .I "global options" | |
73 | may be given. The following global options are supported: | |
74 | .TP | |
75 | .BR "\-h, \-\-help " [ \fIcommand ...] | |
76 | Writes a brief summary of | |
77 | .BR dsig 's | |
78 | various options to standard output, and returns a successful exit | |
79 | status. With command names, gives help on those commands. | |
80 | .TP | |
81 | .B "\-v, \-\-version" | |
82 | Writes the program's version number to standard output, and returns a | |
83 | successful exit status. | |
84 | .TP | |
85 | .B "\-u, \-\-usage" | |
86 | Writes a very terse command line summary to standard output, and returns | |
87 | a successful exit status. | |
88 | .TP | |
89 | .BI "\-k, \-\-keyring " file | |
90 | Names the keyring file which | |
91 | .B key | |
92 | is to process. The default keyring, used if this option doesn't specify | |
93 | one, is the file named | |
94 | .B keyring | |
95 | in the current directory. See | |
96 | .BR key (1) | |
97 | and | |
98 | .BR keyring (5) | |
99 | for more details about keyring files. | |
100 | .SH "KEY SETUP" | |
101 | A | |
102 | .I sigalgspec | |
103 | has the form | |
104 | .IR sig \c | |
105 | .RB [ / \c | |
106 | .IR hash ]. | |
107 | If a | |
108 | .B sig | |
109 | attribute is present on the key, then it must have this form; otherwise, | |
110 | the key's type must have the form | |
111 | .BI dsig- \c | |
112 | .IR sigalgspec . | |
113 | Algorithm selections are taken from appropriately-named attributes, or, | |
114 | failing that, from the | |
115 | .IR sigalgspec . | |
116 | .PP | |
117 | The signature algorithm is chosen according to the setting of | |
118 | .I sig | |
119 | as follows. Run | |
120 | .B dsig show sig | |
121 | for a list of supported signature algorithms. | |
122 | .TP | |
123 | .B rsapkcs1 | |
124 | This is almost the same as the RSASSA-PKCS1-v1_5 algorithm described in | |
125 | RFC3447; the difference is that the hash is left bare rather than being | |
45c0fd36 | 126 | wrapped in a DER-encoded |
c65df279 | 127 | .B DigestInfo |
128 | structure. This doesn't affect security since the key can only be used | |
129 | with the one hash function anyway, and dropping the DER wrapping permits | |
130 | rapid adoption of new hash functions. Regardless, use of this algorithm | |
131 | is not recommended, since the padding method has been shown vulnerable | |
132 | to attack. Use the | |
133 | .B rsa | |
134 | algorithm of the | |
135 | .B key add | |
136 | command (see | |
137 | .BR key (1)) | |
138 | to generate the key. | |
139 | .TP | |
140 | .B rsapss | |
141 | This is the RSASSA-PSS algorithm described in RFC3447. It is the | |
142 | preferred RSA-based signature scheme. Use the | |
143 | .B rsa | |
144 | algorithm of the | |
145 | .B key add | |
146 | command (see | |
147 | .BR key (1)) | |
148 | to generate the key. | |
149 | .TP | |
150 | .B dsa | |
45c0fd36 | 151 | This is the DSA algorithm described in FIPS180-1 and FIPS180-2. Use the |
c65df279 | 152 | .B dsa |
153 | algorithm of the | |
154 | .B key add | |
155 | command (see | |
156 | .BR key (1)) | |
157 | to generate the key. | |
158 | .TP | |
159 | .B ecdsa | |
160 | This is the ECDSA algorithm described in ANSI X9.62 and FIPS180-2. Use | |
161 | the | |
162 | .B ec | |
163 | algorithm of the | |
164 | .B key add | |
165 | command (see | |
166 | .BR key (1)) | |
167 | to generate the key. | |
168 | .TP | |
169 | .B kcdsa | |
170 | This is the revised KCDSA (Korean Certificate-based Digital Signature | |
171 | Algorithm) described in | |
172 | .I The Revised Version of KCDSA | |
173 | .RB ( http://dasan.sejong.ac.kr/~chlim/pub/kcdsa1.ps ). | |
174 | Use the | |
175 | .B dh | |
176 | algorithm of the | |
177 | .B key add | |
178 | command with the | |
179 | .B \-LS | |
180 | options (see | |
181 | .BR key (1)) | |
182 | to generate the key. | |
183 | .TP | |
184 | .B eckcdsa | |
185 | This is an unofficial elliptic-curve analogue of the KCDSA algorithm. | |
186 | Use the | |
187 | .B ec | |
188 | algorithm of the | |
189 | .B key add | |
190 | command (see | |
191 | .BR key (1)) | |
192 | to generate the key. | |
193 | .PP | |
194 | As well as the signature algorithm itself, a hash function is used. | |
195 | This is taken from the | |
196 | .B hash | |
197 | attribute on the key, or, failing that, from the | |
198 | .I hash | |
199 | specified in the | |
200 | .IR sigalgspec , | |
201 | or, if that is absent, determined by the signature algorithm as follows. | |
202 | .hP \*o | |
203 | For | |
204 | .BR rsapkcs1 , | |
205 | .BR rsapss , | |
206 | .BR dsa , | |
207 | and | |
208 | .BR ecdsa , | |
209 | the default hash function is | |
210 | .BR sha . | |
211 | .hP \*o | |
212 | For | |
45c0fd36 | 213 | .BR kcdsa |
c65df279 | 214 | and |
215 | .BR eckcdsa , | |
216 | the default hash function is | |
217 | .BR has160 . | |
218 | .PP | |
219 | Run | |
220 | .B dsig show hash | |
221 | for a list of supported hash functions. | |
222 | .SH "COMMAND REFERENCE" | |
223 | .SS help | |
224 | The | |
225 | .B help | |
226 | command behaves exactly as the | |
227 | .B \-\-help | |
228 | option. With no arguments, it shows an overview of | |
229 | .BR dsig 's | |
230 | options; with arguments, it describes the named subcommands. | |
231 | .SS show | |
232 | The | |
233 | .B show | |
234 | command prints various lists of tokens understood by | |
235 | .BR dsig . | |
236 | With no arguments, it prints all of the lists; with arguments, it prints | |
237 | just the named lists, in order. The recognized lists can be enumerated | |
238 | using the | |
239 | .VS | |
240 | dsig show list | |
241 | .VE | |
242 | command. The lists are as follows. | |
243 | .TP | |
244 | .B list | |
245 | The lists which can be enumerated by the | |
246 | .B show | |
247 | command. | |
248 | .TP | |
249 | .B sig | |
250 | The signature algorithms which can be used in a key's | |
251 | .B sig | |
252 | attribute. | |
253 | .TP | |
254 | .B hash | |
255 | The hash functions which can be used in a key's | |
256 | .B hash | |
257 | attribute. | |
258 | .SS sign | |
259 | The | |
260 | .B sign | |
261 | command creates a signature for a collection of files. The default | |
262 | behaviour is to read a list of whitespace-separated file names (see | |
263 | below for the precise format) from standard input and write the | |
264 | an output file, containing hashes of the files and a digital signature | |
265 | made by the key | |
266 | .B dsig | |
267 | in the current keyring, to standard output, in plain text with binary | |
268 | values Base64-encoded. It is intended to be used in conjunction with | |
269 | .BR find (1). | |
270 | This behaviour can be modified by specifying command-line options. | |
271 | .TP | |
272 | .B "\-0, \-\-null" | |
273 | Read null-terminated filenames, rather than whitespace-separated names. | |
274 | This is the recommended mode of operation if you have a | |
275 | .BR find (1) | |
276 | which understands the | |
277 | .B \-print0 | |
278 | option. | |
279 | .TP | |
280 | .B "\-b, \-\-binary" | |
281 | Produce output in raw binary rather than the textual output. This isn't | |
282 | a useful thing to do unless you're trying to debug | |
283 | .BR dsig . | |
284 | .TP | |
285 | .B "\-v, \-\-verbose" | |
286 | Makes | |
287 | .B dsig | |
288 | more verbose. At present, this just means that it'll print the hashes | |
289 | of files that it comes across in hex. (Use | |
290 | .BR hashsum (1) | |
291 | if this is the output you actually wanted.) | |
292 | .TP | |
293 | .B "\-q, \-\-quiet" | |
294 | Makes | |
295 | .B dsig | |
296 | less verbose. | |
297 | .TP | |
298 | .BI "\-c, \-\-comment " string | |
299 | Writes | |
300 | .I string | |
301 | as a comment in the output file. The comment's integrity is protected | |
302 | by the signature. | |
303 | .TP | |
cd6eca43 MW |
304 | .BI "\-p, \-\-progress" |
305 | Write a progress meter to standard error while processing large files. | |
306 | .TP | |
c65df279 | 307 | .BI "\-f, \-\-file " name |
308 | Read filenames from | |
309 | .I name | |
310 | instead of from standard input. | |
311 | .TP | |
312 | .BI "\-o, \-\-output " name | |
313 | Write output to | |
314 | .I name | |
315 | instead of to standard output. | |
316 | .TP | |
317 | .BI "\-k, \-\-key " tag | |
318 | Use the key named | |
319 | .I tag | |
320 | rather than the default | |
321 | .BR dsig . | |
322 | .TP | |
323 | .BI "\-e, \-\-expire " date | |
324 | Set the signature to expire at | |
325 | .IR date . | |
326 | The default is to expire 28 days from creation. Use | |
327 | .B forever | |
328 | to make the signature not expire. | |
946c3f72 | 329 | .TP |
330 | .B "\-C, \-\-nocheck" | |
331 | Don't check the private key for validity. This makes signing go much | |
332 | faster, but at the risk of using a duff key, and potentially leaking | |
333 | information about the private key. | |
c65df279 | 334 | .PP |
335 | The whitespace-separated format for filenames allows quoting and | |
336 | escaping of strange characters. The backslash | |
337 | .RB ` \e ' | |
338 | can be used to escape whitespace, quotes, or other special characters | |
339 | (including itself), and to represent special characters using the | |
340 | standard C escape sequences | |
341 | .RB ` \ea ', | |
342 | .RB ` \eb ', | |
343 | .RB ` \ef ', | |
344 | .RB ` \en ', | |
345 | .RB ` \et ', | |
346 | and | |
347 | .RB ` \eb '. | |
348 | A filename can be quoted in | |
349 | .BR ` ... ', | |
350 | .BR ' ... ' | |
351 | or | |
352 | .BR """" ... """". | |
353 | Whitespace within quotes is part of the filename. The quotes must be at | |
354 | the beginning and end of the name. | |
355 | .SS verify | |
356 | The | |
357 | .B verify | |
358 | command will verify signatures made by the | |
359 | .B sign | |
360 | command. With no arguments, it expects to read a text-format signature | |
361 | file from standard input; with an argument, it examines the file it | |
362 | names to see whether it's text or binary. | |
363 | .PP | |
364 | Command-line options provided are: | |
365 | .TP | |
366 | .B "\-v, \-\-verbose" | |
367 | Produce more informational output. The default verbosity level is 1. | |
368 | .TP | |
369 | .B "\-q, \-\-quiet" | |
370 | Produce less information output. | |
946c3f72 | 371 | .TP |
cd6eca43 MW |
372 | .BI "\-p, \-\-progress" |
373 | Write a progress meter to standard error while processing large files. | |
374 | .TP | |
946c3f72 | 375 | .B "\-C, \-\-nocheck" |
376 | Don't check the public key for validity. This makes verification go | |
377 | much faster, but at the risk of using a duff key, and potentially | |
378 | accepting false signatures. | |
c65df279 | 379 | .PP |
380 | Output is written to standard output in a machine-readable format. | |
381 | Formatting errors cause the program to write a diagnostic to standard | |
382 | error and exit nonzero as usual. Lines begin with a keyword: | |
383 | .TP | |
384 | .BI "FAIL " reason | |
385 | An error prevented verification. | |
386 | .TP | |
387 | .BI "BAD " reason | |
388 | The signature is bad: some file had the wrong hash or the signature is | |
45c0fd36 | 389 | invalid. |
c65df279 | 390 | .TP |
391 | .BI "WARN " reason | |
392 | .B dsig | |
393 | encountered a situation which may or may not invalidate the signature. | |
394 | .TP | |
395 | .BI "OK " message | |
396 | The signature verified correctly. | |
397 | .TP | |
398 | .BI "INFO " note | |
45c0fd36 | 399 | Any other information. |
c65df279 | 400 | .PP |
401 | The information written at the various verbosity levels is as follows. | |
402 | .hP 0. | |
403 | No output. Watch the exit status. | |
404 | .B dsig | |
405 | exits zero if the signature was good. | |
406 | .hP 1. | |
407 | All | |
408 | .BR OK , | |
409 | .B FAIL | |
410 | and | |
411 | .B WARN | |
412 | messages are printed. | |
413 | .hP 2. | |
414 | As for level 1; also | |
415 | .B BAD | |
416 | messages are printed describing reasons why the signature verification | |
417 | failed, and an | |
418 | .B INFO | |
419 | message is printed showing the signature file's comment if any. | |
420 | .hP 3. | |
421 | As for level 2; also | |
422 | .B INFO | |
423 | messages are shown listing the signing program's identification string, | |
424 | the signing key, the signature and expiry dates, and actual signature | |
425 | verification. | |
426 | .hP 4. | |
427 | As for level 3; also | |
428 | .B INFO | |
429 | messages are printed for each file covered, showing its name and hash. | |
430 | .SH "OUTPUT FORMAT" | |
431 | There are two output formats: textual and binary. The hash used in the | |
432 | digital signature is always computed on the | |
433 | .I binary | |
434 | version of the data, regardless of the external representation. | |
435 | .SS "Textual format" | |
436 | Within the file, whitespace and comments between strings are ignored. A | |
437 | comment begins with a hash | |
438 | .RB (` # ') | |
439 | and extends until the next newline. | |
440 | .PP | |
441 | Strings are either quoted or whitespace-delimited. A string may be | |
442 | quoted by | |
443 | .BR ` ... ', | |
444 | .BR ' ... ' | |
445 | or | |
446 | .BR """" ... """". | |
447 | The end-quote character can be backslash-escaped within the string. An | |
448 | occurrence of the unescaped end-quote character terminates the string. | |
449 | A whitespace-delimited string is terminated by any unescaped whitespace | |
450 | character. The C-language escape sequences | |
451 | .RB ` \ea ', | |
452 | .RB ` \eb ', | |
453 | .RB ` \ef ', | |
454 | .RB ` \en ', | |
455 | .RB ` \et ', | |
456 | and | |
457 | .RB ` \eb ' | |
458 | are recognized within either kind of string. | |
459 | .PP | |
460 | Blocks within the file consist of sequences of strings. The first | |
461 | string is a | |
462 | .I tag | |
463 | \(en a simple string ending in a colon | |
464 | .RB (` : ') | |
465 | \(en which describes the format of the remaining strings. | |
466 | .SS "Binary format" | |
467 | The file consists of a sequence of blocks, each of which begins with a | |
468 | tag byte. The format of the test of the block depends on the tag. | |
469 | Strings are null-terminated; all integers are in network byte order. | |
470 | .PP | |
471 | A binary file always begins with an ident block, which has a tag of 0. | |
472 | .SS "Block types" | |
473 | The following block types are known. They must appear in the order | |
474 | given, and except where noted must appear exactly once each. | |
475 | .TP | |
476 | .BR "ident: " (0) | |
477 | Identification string of the generating program. | |
478 | .BR "keyid: " (1) | |
479 | The signing key's id, as eight hex digits (text) or a 32-bit integer | |
480 | (binary). | |
481 | .TP | |
482 | .BR "comment: " (2) | |
483 | The comment string set with the | |
484 | .B \-c | |
485 | option to the | |
486 | .B sign | |
487 | command. This block need not appear. | |
488 | .TP | |
489 | .BR "date: " (3) | |
490 | The date the signature was made. In a text file, this has the form | |
45c0fd36 | 491 | .IB yyyy-mm-dd |
c65df279 | 492 | .IB hh:mm:ss |
493 | .IR timezone ; | |
494 | in a binary file, it's a 64-bit integer representing the POSIX time. | |
495 | .TP | |
496 | .BR "expires: " (4) | |
497 | The expiry time of the signature, expressed as for | |
498 | .BR date: . | |
499 | A non-expiring signature is represented by the string | |
500 | .B forever | |
501 | in text files, or all-bits-set in binary. | |
502 | .TP | |
503 | .BR "file: " (5) | |
504 | A file hash. In text, this is two strings which are the Base-64-encoded | |
505 | hash and the file name; in binary, this is a 16-bit hash length, the raw | |
506 | hash, and the null-terminated filename. There can be any number of | |
507 | .B file: | |
508 | blocks. | |
509 | .TP | |
510 | .BR "signature: " (6) | |
511 | The signature. In text, this is the Base-64-encoded signature; in | |
512 | binary, it is a 16-bit length followed by the binary signature. | |
513 | .PP | |
514 | The signature covers the | |
515 | .I binary | |
516 | representations of the file's | |
517 | .BR date: , | |
518 | .B expires: | |
519 | and | |
520 | .B file: | |
521 | blocks. | |
522 | .SH "SEE ALSO" | |
523 | .BR key (1), | |
524 | .BR hashsum (1), | |
525 | .BR catcrypt (1), | |
fa54fe1e | 526 | .BR catsign (1), |
c65df279 | 527 | .BR keyring (5). |
528 | .SH AUTHOR | |
f387fcb1 | 529 | Mark Wooding, <mdw@distorted.org.uk> |