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Avoid catch-22 with README.main not being distributed but having the
[gnupg.git] / g10 / seckey-cert.c
blob1398b181bd803d10ac31eb36f7357cd4fe62889b
1 /* seckey-cert.c - secret key certificate packet handling
2 * Copyright (C) 1998, 1999, 2000, 2001, 2002,
3 * 2006, 2009 Free Software Foundation, Inc.
4 *
5 * This file is part of GnuPG.
6 *
7 * GnuPG is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 3 of the License, or
10 * (at your option) any later version.
11 *
12 * GnuPG is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, see <http://www.gnu.org/licenses/>.
19 */
20
21 #include <config.h>
22 #include <stdio.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <assert.h>
26
27 #include "gpg.h"
28 #include "util.h"
29 #include "packet.h"
30 #include "keydb.h"
31 #include "cipher.h"
32 #include "main.h"
33 #include "options.h"
34 #include "i18n.h"
35 #include "status.h"
36 #include "pkglue.h"
37
38 static int
39 do_check( PKT_secret_key *sk, const char *tryagain_text, int mode,
40 int *canceled )
41 {
42 gpg_error_t err;
43 byte *buffer;
44 u16 csum=0;
45 int i, res;
46 size_t nbytes;
47
48 if( sk->is_protected ) { /* remove the protection */
49 DEK *dek = NULL;
50 u32 keyid[4]; /* 4! because we need two of them */
51 gcry_cipher_hd_t cipher_hd=NULL;
52 PKT_secret_key *save_sk;
53
54 if( sk->protect.s2k.mode == 1001 ) {
55 log_info(_("secret key parts are not available\n"));
56 return G10ERR_UNU_SECKEY;
57 }
58 if( sk->protect.algo == CIPHER_ALGO_NONE )
59 BUG();
60 if( openpgp_cipher_test_algo( sk->protect.algo ) ) {
61 log_info(_("protection algorithm %d%s is not supported\n"),
62 sk->protect.algo,sk->protect.algo==1?" (IDEA)":"" );
63 if (sk->protect.algo==CIPHER_ALGO_IDEA)
64 {
65 write_status (STATUS_RSA_OR_IDEA);
66 idea_cipher_warn (0);
67 }
68 return G10ERR_CIPHER_ALGO;
69 }
70 if(gcry_md_test_algo (sk->protect.s2k.hash_algo))
71 {
72 log_info(_("protection digest %d is not supported\n"),
73 sk->protect.s2k.hash_algo);
74 return G10ERR_DIGEST_ALGO;
75 }
76 keyid_from_sk( sk, keyid );
77 keyid[2] = keyid[3] = 0;
78 if( !sk->is_primary ) {
79 keyid[2] = sk->main_keyid[0];
80 keyid[3] = sk->main_keyid[1];
81 }
82 dek = passphrase_to_dek( keyid, sk->pubkey_algo, sk->protect.algo,
83 &sk->protect.s2k, mode,
84 tryagain_text, canceled );
85 if (!dek && canceled && *canceled)
86 return G10ERR_GENERAL;
87
88
89 err = openpgp_cipher_open (&cipher_hd, sk->protect.algo,
90 GCRY_CIPHER_MODE_CFB,
91 (GCRY_CIPHER_SECURE
92 | (sk->protect.algo >= 100 ?
93 0 : GCRY_CIPHER_ENABLE_SYNC)));
94 if (err)
95 log_fatal ("cipher open failed: %s\n", gpg_strerror (err) );
96
97 err = gcry_cipher_setkey (cipher_hd, dek->key, dek->keylen);
98 if (err)
99 log_fatal ("set key failed: %s\n", gpg_strerror (err) );
100
101 xfree(dek);
102 save_sk = copy_secret_key( NULL, sk );
103
104 gcry_cipher_setiv ( cipher_hd, sk->protect.iv, sk->protect.ivlen );
105
106 csum = 0;
107 if( sk->version >= 4 ) {
108 int ndata;
109 unsigned int ndatabits;
110 byte *p, *data;
111 u16 csumc = 0;
112
113 i = pubkey_get_npkey(sk->pubkey_algo);
114
115 assert ( gcry_mpi_get_flag (sk->skey[i], GCRYMPI_FLAG_OPAQUE ));
116 p = gcry_mpi_get_opaque ( sk->skey[i], &ndatabits );
117 ndata = (ndatabits+7)/8;
118
119 if ( ndata > 1 )
120 csumc = p[ndata-2] << 8 | p[ndata-1];
121 data = xmalloc_secure ( ndata );
122 gcry_cipher_decrypt ( cipher_hd, data, ndata, p, ndata );
123 gcry_mpi_release (sk->skey[i]); sk->skey[i] = NULL ;
124
125 p = data;
126 if (sk->protect.sha1chk) {
127 /* This is the new SHA1 checksum method to detect
128 tampering with the key as used by the Klima/Rosa
129 attack */
130 sk->csum = 0;
131 csum = 1;
132 if( ndata < 20 )
133 log_error("not enough bytes for SHA-1 checksum\n");
134 else {
135 gcry_md_hd_t h;
136
137 if ( gcry_md_open (&h, DIGEST_ALGO_SHA1, 1))
138 BUG(); /* Algo not available. */
139 gcry_md_write (h, data, ndata - 20);
140 gcry_md_final (h);
141 if (!memcmp (gcry_md_read (h, DIGEST_ALGO_SHA1),
142 data + ndata - 20, 20) )
143 {
144 /* Digest does match. We have to keep the old
145 style checksum in sk->csum, so that the
146 test used for unprotected keys does work.
147 This test gets used when we are adding new
148 keys. */
149 sk->csum = csum = checksum (data, ndata-20);
150 }
151 gcry_md_close (h);
152 }
153 }
154 else {
155 if( ndata < 2 ) {
156 log_error("not enough bytes for checksum\n");
157 sk->csum = 0;
158 csum = 1;
159 }
160 else {
161 csum = checksum( data, ndata-2);
162 sk->csum = data[ndata-2] << 8 | data[ndata-1];
163 if ( sk->csum != csum ) {
164 /* This is a PGP 7.0.0 workaround */
165 sk->csum = csumc; /* take the encrypted one */
166 }
167 }
168 }
169
170 /* Must check it here otherwise the mpi_read_xx would fail
171 because the length may have an arbitrary value */
172 if( sk->csum == csum ) {
173 for( ; i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
174 if ( gcry_mpi_scan( &sk->skey[i], GCRYMPI_FMT_PGP,
175 p, ndata, &nbytes))
176 {
177 /* Checksum was okay, but not correctly
178 decrypted. */
179 sk->csum = 0;
180 csum = 1;
181 break;
182 }
183 ndata -= nbytes;
184 p += nbytes;
185 }
186 /* Note: at this point ndata should be 2 for a simple
187 checksum or 20 for the sha1 digest */
188 }
189 xfree(data);
190 }
191 else {
192 for(i=pubkey_get_npkey(sk->pubkey_algo);
193 i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
194 byte *p;
195 size_t ndata;
196 unsigned int ndatabits;
197
198 assert (gcry_mpi_get_flag (sk->skey[i], GCRYMPI_FLAG_OPAQUE));
199 p = gcry_mpi_get_opaque (sk->skey[i], &ndatabits);
200 ndata = (ndatabits+7)/8;
201 assert (ndata >= 2);
202 assert (ndata == ((p[0] << 8 | p[1]) + 7)/8 + 2);
203 buffer = xmalloc_secure (ndata);
204 gcry_cipher_sync (cipher_hd);
205 buffer[0] = p[0];
206 buffer[1] = p[1];
207 gcry_cipher_decrypt (cipher_hd, buffer+2, ndata-2,
208 p+2, ndata-2);
209 csum += checksum (buffer, ndata);
210 gcry_mpi_release (sk->skey[i]);
211
212 err = gcry_mpi_scan( &sk->skey[i], GCRYMPI_FMT_PGP,
213 buffer, ndata, &ndata );
214 xfree (buffer);
215 if (err)
216 {
217 /* Checksum was okay, but not correctly
218 decrypted. */
219 sk->csum = 0;
220 csum = 1;
221 break;
222 }
223 /* csum += checksum_mpi (sk->skey[i]); */
224 }
225 }
226 gcry_cipher_close ( cipher_hd );
227
228 /* Now let's see whether we have used the correct passphrase. */
229 if( csum != sk->csum ) {
230 copy_secret_key( sk, save_sk );
231 passphrase_clear_cache ( keyid, NULL, sk->pubkey_algo );
232 free_secret_key( save_sk );
233 return gpg_error (GPG_ERR_BAD_PASSPHRASE);
234 }
235
236 /* The checksum may fail, so we also check the key itself. */
237 res = pk_check_secret_key ( sk->pubkey_algo, sk->skey );
238 if( res ) {
239 copy_secret_key( sk, save_sk );
240 passphrase_clear_cache ( keyid, NULL, sk->pubkey_algo );
241 free_secret_key( save_sk );
242 return gpg_error (GPG_ERR_BAD_PASSPHRASE);
243 }
244 free_secret_key( save_sk );
245 sk->is_protected = 0;
246 }
247 else { /* not protected, assume it is okay if the checksum is okay */
248 csum = 0;
249 for(i=pubkey_get_npkey(sk->pubkey_algo);
250 i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
251 csum += checksum_mpi( sk->skey[i] );
252 }
253 if( csum != sk->csum )
254 return G10ERR_CHECKSUM;
255 }
256
257 return 0;
258 }
259
260
261
262 /****************
263 * Check the secret key
264 * Ask up to 3 (or n) times for a correct passphrase
265 * If n is negative, disable the key info prompt and make n=abs(n)
266 */
267 int
268 check_secret_key( PKT_secret_key *sk, int n )
269 {
270 int rc = gpg_error (GPG_ERR_BAD_PASSPHRASE);
271 int i,mode;
272
273 if (sk && sk->is_protected && sk->protect.s2k.mode == 1002)
274 return 0; /* Let the scdaemon handle this. */
275
276 if(n<0)
277 {
278 n=abs(n);
279 mode=1;
280 }
281 else
282 mode=0;
283
284 if( n < 1 )
285 n = 3; /* Use the default value */
286
287 for(i=0; i < n && gpg_err_code (rc) == GPG_ERR_BAD_PASSPHRASE; i++ ) {
288 int canceled = 0;
289 const char *tryagain = NULL;
290 if (i) {
291 tryagain = N_("Invalid passphrase; please try again");
292 log_info (_("%s ...\n"), _(tryagain));
293 }
294 rc = do_check( sk, tryagain, mode, &canceled );
295 if ( gpg_err_code (rc) == GPG_ERR_BAD_PASSPHRASE
296 && is_status_enabled () ) {
297 u32 kid[2];
298 char buf[50];
299
300 keyid_from_sk( sk, kid );
301 sprintf(buf, "%08lX%08lX", (ulong)kid[0], (ulong)kid[1]);
302 write_status_text( STATUS_BAD_PASSPHRASE, buf );
303 }
304 if( have_static_passphrase() || canceled)
305 break;
306 }
307
308 if( !rc )
309 write_status( STATUS_GOOD_PASSPHRASE );
310
311 return rc;
312 }
313
314 /****************
315 * check whether the secret key is protected.
316 * Returns: 0 not protected, -1 on error or the protection algorithm
317 * -2 indicates a card stub.
318 * -3 indicates a not-online stub.
319 */
320 int
321 is_secret_key_protected( PKT_secret_key *sk )
322 {
323 return sk->is_protected?
324 sk->protect.s2k.mode == 1002? -2 :
325 sk->protect.s2k.mode == 1001? -3 : sk->protect.algo : 0;
326 }
327
328
329
330 /****************
331 * Protect the secret key with the passphrase from DEK
332 */
333 int
334 protect_secret_key( PKT_secret_key *sk, DEK *dek )
335 {
336 int i,j, rc = 0;
337 byte *buffer;
338 size_t nbytes;
339 u16 csum;
340
341 if( !dek )
342 return 0;
343
344 if( !sk->is_protected ) { /* okay, apply the protection */
345 gcry_cipher_hd_t cipher_hd=NULL;
346
347 if ( openpgp_cipher_test_algo ( sk->protect.algo ) ) {
348 /* Unsupport protection algorithm. */
349 rc = gpg_error (GPG_ERR_CIPHER_ALGO);
350 }
351 else {
352 print_cipher_algo_note( sk->protect.algo );
353
354 if ( openpgp_cipher_open (&cipher_hd, sk->protect.algo,
355 GCRY_CIPHER_MODE_CFB,
356 (GCRY_CIPHER_SECURE
357 | (sk->protect.algo >= 100 ?
358 0 : GCRY_CIPHER_ENABLE_SYNC))) )
359 BUG();
360 if ( gcry_cipher_setkey ( cipher_hd, dek->key, dek->keylen ) )
361 log_info(_("WARNING: Weak key detected"
362 " - please change passphrase again.\n"));
363 sk->protect.ivlen = openpgp_cipher_get_algo_blklen (sk->protect.algo);
364 assert( sk->protect.ivlen <= DIM(sk->protect.iv) );
365 if( sk->protect.ivlen != 8 && sk->protect.ivlen != 16 )
366 BUG(); /* yes, we are very careful */
367 gcry_create_nonce (sk->protect.iv, sk->protect.ivlen);
368 gcry_cipher_setiv (cipher_hd, sk->protect.iv, sk->protect.ivlen);
369 if( sk->version >= 4 ) {
370 byte *bufarr[PUBKEY_MAX_NSKEY];
371 size_t narr[PUBKEY_MAX_NSKEY];
372 unsigned int nbits[PUBKEY_MAX_NSKEY];
373 int ndata=0;
374 byte *p, *data;
375
376 for (j=0, i = pubkey_get_npkey(sk->pubkey_algo);
377 i < pubkey_get_nskey(sk->pubkey_algo); i++, j++ )
378 {
379 assert (!gcry_mpi_get_flag (sk->skey[i],
380 GCRYMPI_FLAG_OPAQUE));
381 if (gcry_mpi_aprint (GCRYMPI_FMT_USG, bufarr+j,
382 narr+j, sk->skey[i]))
383 BUG();
384 nbits[j] = gcry_mpi_get_nbits (sk->skey[i]);
385 ndata += narr[j] + 2;
386 }
387 for ( ; j < PUBKEY_MAX_NSKEY; j++ )
388 bufarr[j] = NULL;
389
390 ndata += opt.simple_sk_checksum? 2 : 20; /* for checksum */
391
392 data = xmalloc_secure( ndata );
393 p = data;
394 for(j=0; j < PUBKEY_MAX_NSKEY && bufarr[j]; j++ ) {
395 p[0] = nbits[j] >> 8 ;
396 p[1] = nbits[j];
397 p += 2;
398 memcpy(p, bufarr[j], narr[j] );
399 p += narr[j];
400 xfree(bufarr[j]);
401 }
402
403 if (opt.simple_sk_checksum) {
404 log_info (_("generating the deprecated 16-bit checksum"
405 " for secret key protection\n"));
406 csum = checksum( data, ndata-2);
407 sk->csum = csum;
408 *p++ = csum >> 8;
409 *p++ = csum;
410 sk->protect.sha1chk = 0;
411 }
412 else {
413 gcry_md_hd_t h;
414
415 if (gcry_md_open (&h, GCRY_MD_SHA1, 1))
416 BUG(); /* Algo not available. */
417 gcry_md_write (h, data, ndata - 20);
418 gcry_md_final (h);
419 memcpy (p, gcry_md_read (h, DIGEST_ALGO_SHA1), 20);
420 p += 20;
421 gcry_md_close (h);
422 sk->csum = csum = 0;
423 sk->protect.sha1chk = 1;
424 }
425 assert( p == data+ndata );
426
427 gcry_cipher_encrypt (cipher_hd, data, ndata, NULL, 0);
428 for (i = pubkey_get_npkey(sk->pubkey_algo);
429 i < pubkey_get_nskey(sk->pubkey_algo); i++ )
430 {
431 gcry_mpi_release (sk->skey[i]);
432 sk->skey[i] = NULL;
433 }
434 i = pubkey_get_npkey(sk->pubkey_algo);
435 sk->skey[i] = gcry_mpi_set_opaque (NULL, data, ndata*8 );
436 }
437 else {
438 csum = 0;
439 for(i=pubkey_get_npkey(sk->pubkey_algo);
440 i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
441 byte *data;
442 unsigned int nbits;
443
444 csum += checksum_mpi (sk->skey[i]);
445
446 if (gcry_mpi_aprint (GCRYMPI_FMT_USG, &buffer,
447 &nbytes, sk->skey[i] ))
448 BUG();
449 gcry_cipher_sync (cipher_hd);
450 assert (!gcry_mpi_get_flag (sk->skey[i],
451 GCRYMPI_FLAG_OPAQUE));
452
453 data = xmalloc (nbytes+2); /* fixme: need xtrymalloc. */
454 nbits = gcry_mpi_get_nbits (sk->skey[i]);
455 assert (nbytes == (nbits + 7)/8);
456 data[0] = nbits >> 8;
457 data[1] = nbits;
458 gcry_cipher_encrypt (cipher_hd, data+2, nbytes,
459 buffer, nbytes);
460 xfree( buffer );
461
462 gcry_mpi_release (sk->skey[i]);
463 sk->skey[i] = gcry_mpi_set_opaque (NULL,
464 data, (nbytes+2)*8 );
465 }
466 sk->csum = csum;
467 }
468 sk->is_protected = 1;
469 gcry_cipher_close (cipher_hd);
470 }
471 }
472 return rc;
473 }
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