/
dh.c
468 lines (425 loc) · 14.6 KB
/
dh.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
/* $OpenBSD: dh.c,v 1.63 2018/02/07 02:06:50 jsing Exp $ */
/*
* Copyright (c) 2000 Niels Provos. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#ifdef WITH_OPENSSL
#include <openssl/bn.h>
#include <openssl/dh.h>
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include "dh.h"
#include "pathnames.h"
#include "log.h"
#include "misc.h"
#include "ssherr.h"
static int
parse_prime(int linenum, char *line, struct dhgroup *dhg)
{
char *cp, *arg;
char *strsize, *gen, *prime;
const char *errstr = NULL;
long long n;
dhg->p = dhg->g = NULL;
cp = line;
if ((arg = strdelim(&cp)) == NULL)
return 0;
/* Ignore leading whitespace */
if (*arg == '\0')
arg = strdelim(&cp);
if (!arg || !*arg || *arg == '#')
return 0;
/* time */
if (cp == NULL || *arg == '\0')
goto truncated;
arg = strsep(&cp, " "); /* type */
if (cp == NULL || *arg == '\0')
goto truncated;
/* Ensure this is a safe prime */
n = strtonum(arg, 0, 5, &errstr);
if (errstr != NULL || n != MODULI_TYPE_SAFE) {
error("moduli:%d: type is not %d", linenum, MODULI_TYPE_SAFE);
goto fail;
}
arg = strsep(&cp, " "); /* tests */
if (cp == NULL || *arg == '\0')
goto truncated;
/* Ensure prime has been tested and is not composite */
n = strtonum(arg, 0, 0x1f, &errstr);
if (errstr != NULL ||
(n & MODULI_TESTS_COMPOSITE) || !(n & ~MODULI_TESTS_COMPOSITE)) {
error("moduli:%d: invalid moduli tests flag", linenum);
goto fail;
}
arg = strsep(&cp, " "); /* tries */
if (cp == NULL || *arg == '\0')
goto truncated;
n = strtonum(arg, 0, 1<<30, &errstr);
if (errstr != NULL || n == 0) {
error("moduli:%d: invalid primality trial count", linenum);
goto fail;
}
strsize = strsep(&cp, " "); /* size */
if (cp == NULL || *strsize == '\0' ||
(dhg->size = (int)strtonum(strsize, 0, 64*1024, &errstr)) == 0 ||
errstr) {
error("moduli:%d: invalid prime length", linenum);
goto fail;
}
/* The whole group is one bit larger */
dhg->size++;
gen = strsep(&cp, " "); /* gen */
if (cp == NULL || *gen == '\0')
goto truncated;
prime = strsep(&cp, " "); /* prime */
if (cp != NULL || *prime == '\0') {
truncated:
error("moduli:%d: truncated", linenum);
goto fail;
}
if ((dhg->g = BN_new()) == NULL ||
(dhg->p = BN_new()) == NULL) {
error("parse_prime: BN_new failed");
goto fail;
}
if (BN_hex2bn(&dhg->g, gen) == 0) {
error("moduli:%d: could not parse generator value", linenum);
goto fail;
}
if (BN_hex2bn(&dhg->p, prime) == 0) {
error("moduli:%d: could not parse prime value", linenum);
goto fail;
}
if (BN_num_bits(dhg->p) != dhg->size) {
error("moduli:%d: prime has wrong size: actual %d listed %d",
linenum, BN_num_bits(dhg->p), dhg->size - 1);
goto fail;
}
if (BN_cmp(dhg->g, BN_value_one()) <= 0) {
error("moduli:%d: generator is invalid", linenum);
goto fail;
}
return 1;
fail:
BN_clear_free(dhg->g);
BN_clear_free(dhg->p);
dhg->g = dhg->p = NULL;
return 0;
}
DH *
choose_dh(int min, int wantbits, int max)
{
FILE *f;
char line[4096];
int best, bestcount, which;
int linenum;
struct dhgroup dhg;
if ((f = fopen(_PATH_DH_MODULI, "r")) == NULL) {
logit("WARNING: could not open %s (%s), using fixed modulus",
_PATH_DH_MODULI, strerror(errno));
return (dh_new_group_fallback(max));
}
linenum = 0;
best = bestcount = 0;
while (fgets(line, sizeof(line), f)) {
linenum++;
if (!parse_prime(linenum, line, &dhg))
continue;
BN_clear_free(dhg.g);
BN_clear_free(dhg.p);
if (dhg.size > max || dhg.size < min)
continue;
if ((dhg.size > wantbits && dhg.size < best) ||
(dhg.size > best && best < wantbits)) {
best = dhg.size;
bestcount = 0;
}
if (dhg.size == best)
bestcount++;
}
rewind(f);
if (bestcount == 0) {
fclose(f);
logit("WARNING: no suitable primes in %s", _PATH_DH_MODULI);
return (dh_new_group_fallback(max));
}
linenum = 0;
which = arc4random_uniform(bestcount);
while (fgets(line, sizeof(line), f)) {
if (!parse_prime(linenum, line, &dhg))
continue;
if ((dhg.size > max || dhg.size < min) ||
dhg.size != best ||
linenum++ != which) {
BN_clear_free(dhg.g);
BN_clear_free(dhg.p);
continue;
}
break;
}
fclose(f);
if (linenum != which+1) {
logit("WARNING: line %d disappeared in %s, giving up",
which, _PATH_DH_MODULI);
return (dh_new_group_fallback(max));
}
return (dh_new_group(dhg.g, dhg.p));
}
/* diffie-hellman-groupN-sha1 */
int
dh_pub_is_valid(DH *dh, BIGNUM *dh_pub)
{
int i;
int n = BN_num_bits(dh_pub);
int bits_set = 0;
BIGNUM *tmp;
if (dh_pub->neg) {
logit("invalid public DH value: negative");
return 0;
}
if (BN_cmp(dh_pub, BN_value_one()) != 1) { /* pub_exp <= 1 */
logit("invalid public DH value: <= 1");
return 0;
}
if ((tmp = BN_new()) == NULL) {
error("%s: BN_new failed", __func__);
return 0;
}
if (!BN_sub(tmp, dh->p, BN_value_one()) ||
BN_cmp(dh_pub, tmp) != -1) { /* pub_exp > p-2 */
BN_clear_free(tmp);
logit("invalid public DH value: >= p-1");
return 0;
}
BN_clear_free(tmp);
for (i = 0; i <= n; i++)
if (BN_is_bit_set(dh_pub, i))
bits_set++;
debug2("bits set: %d/%d", bits_set, BN_num_bits(dh->p));
/*
* if g==2 and bits_set==1 then computing log_g(dh_pub) is trivial
*/
if (bits_set < 4) {
logit("invalid public DH value (%d/%d)",
bits_set, BN_num_bits(dh->p));
return 0;
}
return 1;
}
int
dh_gen_key(DH *dh, int need)
{
int pbits;
if (need < 0 || dh->p == NULL ||
(pbits = BN_num_bits(dh->p)) <= 0 ||
need > INT_MAX / 2 || 2 * need > pbits)
return SSH_ERR_INVALID_ARGUMENT;
if (need < 256)
need = 256;
/*
* Pollard Rho, Big step/Little Step attacks are O(sqrt(n)),
* so double requested need here.
*/
dh->length = MINIMUM(need * 2, pbits - 1);
if (DH_generate_key(dh) == 0 ||
!dh_pub_is_valid(dh, dh->pub_key)) {
BN_clear_free(dh->priv_key);
return SSH_ERR_LIBCRYPTO_ERROR;
}
return 0;
}
DH *
dh_new_group_asc(const char *gen, const char *modulus)
{
DH *dh;
if ((dh = DH_new()) == NULL)
return NULL;
if (BN_hex2bn(&dh->p, modulus) == 0 ||
BN_hex2bn(&dh->g, gen) == 0) {
DH_free(dh);
return NULL;
}
return (dh);
}
/*
* This just returns the group, we still need to generate the exchange
* value.
*/
DH *
dh_new_group(BIGNUM *gen, BIGNUM *modulus)
{
DH *dh;
if ((dh = DH_new()) == NULL)
return NULL;
dh->p = modulus;
dh->g = gen;
return (dh);
}
/* rfc2409 "Second Oakley Group" (1024 bits) */
DH *
dh_new_group1(void)
{
static char *gen = "2", *group1 =
"FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
"29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
"E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
"EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE65381"
"FFFFFFFF" "FFFFFFFF";
return (dh_new_group_asc(gen, group1));
}
/* rfc3526 group 14 "2048-bit MODP Group" */
DH *
dh_new_group14(void)
{
static char *gen = "2", *group14 =
"FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
"29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
"E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
"EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D"
"C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
"83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
"670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B"
"E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9"
"DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510"
"15728E5A" "8AACAA68" "FFFFFFFF" "FFFFFFFF";
return (dh_new_group_asc(gen, group14));
}
/* rfc3526 group 16 "4096-bit MODP Group" */
DH *
dh_new_group16(void)
{
static char *gen = "2", *group16 =
"FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
"29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
"E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
"EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D"
"C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
"83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
"670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B"
"E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9"
"DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510"
"15728E5A" "8AAAC42D" "AD33170D" "04507A33" "A85521AB" "DF1CBA64"
"ECFB8504" "58DBEF0A" "8AEA7157" "5D060C7D" "B3970F85" "A6E1E4C7"
"ABF5AE8C" "DB0933D7" "1E8C94E0" "4A25619D" "CEE3D226" "1AD2EE6B"
"F12FFA06" "D98A0864" "D8760273" "3EC86A64" "521F2B18" "177B200C"
"BBE11757" "7A615D6C" "770988C0" "BAD946E2" "08E24FA0" "74E5AB31"
"43DB5BFC" "E0FD108E" "4B82D120" "A9210801" "1A723C12" "A787E6D7"
"88719A10" "BDBA5B26" "99C32718" "6AF4E23C" "1A946834" "B6150BDA"
"2583E9CA" "2AD44CE8" "DBBBC2DB" "04DE8EF9" "2E8EFC14" "1FBECAA6"
"287C5947" "4E6BC05D" "99B2964F" "A090C3A2" "233BA186" "515BE7ED"
"1F612970" "CEE2D7AF" "B81BDD76" "2170481C" "D0069127" "D5B05AA9"
"93B4EA98" "8D8FDDC1" "86FFB7DC" "90A6C08F" "4DF435C9" "34063199"
"FFFFFFFF" "FFFFFFFF";
return (dh_new_group_asc(gen, group16));
}
/* rfc3526 group 18 "8192-bit MODP Group" */
DH *
dh_new_group18(void)
{
static char *gen = "2", *group16 =
"FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
"29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
"E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
"EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D"
"C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
"83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
"670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B"
"E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9"
"DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510"
"15728E5A" "8AAAC42D" "AD33170D" "04507A33" "A85521AB" "DF1CBA64"
"ECFB8504" "58DBEF0A" "8AEA7157" "5D060C7D" "B3970F85" "A6E1E4C7"
"ABF5AE8C" "DB0933D7" "1E8C94E0" "4A25619D" "CEE3D226" "1AD2EE6B"
"F12FFA06" "D98A0864" "D8760273" "3EC86A64" "521F2B18" "177B200C"
"BBE11757" "7A615D6C" "770988C0" "BAD946E2" "08E24FA0" "74E5AB31"
"43DB5BFC" "E0FD108E" "4B82D120" "A9210801" "1A723C12" "A787E6D7"
"88719A10" "BDBA5B26" "99C32718" "6AF4E23C" "1A946834" "B6150BDA"
"2583E9CA" "2AD44CE8" "DBBBC2DB" "04DE8EF9" "2E8EFC14" "1FBECAA6"
"287C5947" "4E6BC05D" "99B2964F" "A090C3A2" "233BA186" "515BE7ED"
"1F612970" "CEE2D7AF" "B81BDD76" "2170481C" "D0069127" "D5B05AA9"
"93B4EA98" "8D8FDDC1" "86FFB7DC" "90A6C08F" "4DF435C9" "34028492"
"36C3FAB4" "D27C7026" "C1D4DCB2" "602646DE" "C9751E76" "3DBA37BD"
"F8FF9406" "AD9E530E" "E5DB382F" "413001AE" "B06A53ED" "9027D831"
"179727B0" "865A8918" "DA3EDBEB" "CF9B14ED" "44CE6CBA" "CED4BB1B"
"DB7F1447" "E6CC254B" "33205151" "2BD7AF42" "6FB8F401" "378CD2BF"
"5983CA01" "C64B92EC" "F032EA15" "D1721D03" "F482D7CE" "6E74FEF6"
"D55E702F" "46980C82" "B5A84031" "900B1C9E" "59E7C97F" "BEC7E8F3"
"23A97A7E" "36CC88BE" "0F1D45B7" "FF585AC5" "4BD407B2" "2B4154AA"
"CC8F6D7E" "BF48E1D8" "14CC5ED2" "0F8037E0" "A79715EE" "F29BE328"
"06A1D58B" "B7C5DA76" "F550AA3D" "8A1FBFF0" "EB19CCB1" "A313D55C"
"DA56C9EC" "2EF29632" "387FE8D7" "6E3C0468" "043E8F66" "3F4860EE"
"12BF2D5B" "0B7474D6" "E694F91E" "6DBE1159" "74A3926F" "12FEE5E4"
"38777CB6" "A932DF8C" "D8BEC4D0" "73B931BA" "3BC832B6" "8D9DD300"
"741FA7BF" "8AFC47ED" "2576F693" "6BA42466" "3AAB639C" "5AE4F568"
"3423B474" "2BF1C978" "238F16CB" "E39D652D" "E3FDB8BE" "FC848AD9"
"22222E04" "A4037C07" "13EB57A8" "1A23F0C7" "3473FC64" "6CEA306B"
"4BCBC886" "2F8385DD" "FA9D4B7F" "A2C087E8" "79683303" "ED5BDD3A"
"062B3CF5" "B3A278A6" "6D2A13F8" "3F44F82D" "DF310EE0" "74AB6A36"
"4597E899" "A0255DC1" "64F31CC5" "0846851D" "F9AB4819" "5DED7EA1"
"B1D510BD" "7EE74D73" "FAF36BC3" "1ECFA268" "359046F4" "EB879F92"
"4009438B" "481C6CD7" "889A002E" "D5EE382B" "C9190DA6" "FC026E47"
"9558E447" "5677E9AA" "9E3050E2" "765694DF" "C81F56E8" "80B96E71"
"60C980DD" "98EDD3DF" "FFFFFFFF" "FFFFFFFF";
return (dh_new_group_asc(gen, group16));
}
/* Select fallback group used by DH-GEX if moduli file cannot be read. */
DH *
dh_new_group_fallback(int max)
{
debug3("%s: requested max size %d", __func__, max);
if (max < 3072) {
debug3("using 2k bit group 14");
return dh_new_group14();
} else if (max < 6144) {
debug3("using 4k bit group 16");
return dh_new_group16();
}
debug3("using 8k bit group 18");
return dh_new_group18();
}
/*
* Estimates the group order for a Diffie-Hellman group that has an
* attack complexity approximately the same as O(2**bits).
* Values from NIST Special Publication 800-57: Recommendation for Key
* Management Part 1 (rev 3) limited by the recommended maximum value
* from RFC4419 section 3.
*/
u_int
dh_estimate(int bits)
{
if (bits <= 112)
return 2048;
if (bits <= 128)
return 3072;
if (bits <= 192)
return 7680;
return 8192;
}
#endif /* WITH_OPENSSL */