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fd06fbe0 | 1 | /* $OpenBSD: dh.c,v 1.35 2006/03/27 13:03:54 deraadt Exp $ */ |
94ec8c6b | 2 | /* |
3 | * Copyright (c) 2000 Niels Provos. All rights reserved. | |
4 | * | |
5 | * Redistribution and use in source and binary forms, with or without | |
6 | * modification, are permitted provided that the following conditions | |
7 | * are met: | |
8 | * 1. Redistributions of source code must retain the above copyright | |
9 | * notice, this list of conditions and the following disclaimer. | |
10 | * 2. Redistributions in binary form must reproduce the above copyright | |
11 | * notice, this list of conditions and the following disclaimer in the | |
12 | * documentation and/or other materials provided with the distribution. | |
13 | * | |
14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
15 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
16 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
17 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
18 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
19 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
20 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
21 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
22 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
23 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
24 | */ | |
25 | ||
26 | #include "includes.h" | |
94ec8c6b | 27 | |
28 | #include "xmalloc.h" | |
29 | ||
30 | #include <openssl/bn.h> | |
31 | #include <openssl/dh.h> | |
32 | #include <openssl/evp.h> | |
33 | ||
94ec8c6b | 34 | #include "buffer.h" |
42f11eb2 | 35 | #include "cipher.h" |
94ec8c6b | 36 | #include "kex.h" |
37 | #include "dh.h" | |
42f11eb2 | 38 | #include "pathnames.h" |
39 | #include "log.h" | |
40 | #include "misc.h" | |
94ec8c6b | 41 | |
396c147e | 42 | static int |
94ec8c6b | 43 | parse_prime(int linenum, char *line, struct dhgroup *dhg) |
44 | { | |
45 | char *cp, *arg; | |
46 | char *strsize, *gen, *prime; | |
fd06fbe0 | 47 | const char *errstr = NULL; |
94ec8c6b | 48 | |
49 | cp = line; | |
88299971 | 50 | if ((arg = strdelim(&cp)) == NULL) |
51 | return 0; | |
94ec8c6b | 52 | /* Ignore leading whitespace */ |
53 | if (*arg == '\0') | |
54 | arg = strdelim(&cp); | |
f11fe301 | 55 | if (!arg || !*arg || *arg == '#') |
94ec8c6b | 56 | return 0; |
57 | ||
58 | /* time */ | |
59 | if (cp == NULL || *arg == '\0') | |
60 | goto fail; | |
61 | arg = strsep(&cp, " "); /* type */ | |
62 | if (cp == NULL || *arg == '\0') | |
63 | goto fail; | |
64 | arg = strsep(&cp, " "); /* tests */ | |
65 | if (cp == NULL || *arg == '\0') | |
66 | goto fail; | |
67 | arg = strsep(&cp, " "); /* tries */ | |
68 | if (cp == NULL || *arg == '\0') | |
69 | goto fail; | |
70 | strsize = strsep(&cp, " "); /* size */ | |
71 | if (cp == NULL || *strsize == '\0' || | |
fd06fbe0 | 72 | (dhg->size = (u_int)strtonum(strsize, 0, 64*1024, &errstr)) == 0 || |
73 | errstr) | |
94ec8c6b | 74 | goto fail; |
db1cd2f3 | 75 | /* The whole group is one bit larger */ |
76 | dhg->size++; | |
94ec8c6b | 77 | gen = strsep(&cp, " "); /* gen */ |
78 | if (cp == NULL || *gen == '\0') | |
79 | goto fail; | |
80 | prime = strsep(&cp, " "); /* prime */ | |
81 | if (cp != NULL || *prime == '\0') | |
82 | goto fail; | |
83 | ||
b775c6f2 | 84 | if ((dhg->g = BN_new()) == NULL) |
85 | fatal("parse_prime: BN_new failed"); | |
86 | if ((dhg->p = BN_new()) == NULL) | |
87 | fatal("parse_prime: BN_new failed"); | |
ec1f12d3 | 88 | if (BN_hex2bn(&dhg->g, gen) == 0) |
c8682232 | 89 | goto failclean; |
90 | ||
ec1f12d3 | 91 | if (BN_hex2bn(&dhg->p, prime) == 0) |
c8682232 | 92 | goto failclean; |
93 | ||
94 | if (BN_num_bits(dhg->p) != dhg->size) | |
95 | goto failclean; | |
94ec8c6b | 96 | |
8b0a55ac | 97 | if (BN_is_zero(dhg->g) || BN_is_one(dhg->g)) |
98 | goto failclean; | |
99 | ||
94ec8c6b | 100 | return (1); |
c8682232 | 101 | |
102 | failclean: | |
108d362e | 103 | BN_clear_free(dhg->g); |
104 | BN_clear_free(dhg->p); | |
94ec8c6b | 105 | fail: |
54b974dc | 106 | error("Bad prime description in line %d", linenum); |
94ec8c6b | 107 | return (0); |
108 | } | |
109 | ||
110 | DH * | |
db1cd2f3 | 111 | choose_dh(int min, int wantbits, int max) |
94ec8c6b | 112 | { |
113 | FILE *f; | |
cd744742 | 114 | char line[4096]; |
94ec8c6b | 115 | int best, bestcount, which; |
116 | int linenum; | |
117 | struct dhgroup dhg; | |
118 | ||
e2854364 | 119 | if ((f = fopen(_PATH_DH_MODULI, "r")) == NULL && |
120 | (f = fopen(_PATH_DH_PRIMES, "r")) == NULL) { | |
41e5bd9a | 121 | logit("WARNING: %s does not exist, using fixed modulus", |
122 | _PATH_DH_MODULI); | |
123 | return (dh_new_group14()); | |
94ec8c6b | 124 | } |
125 | ||
126 | linenum = 0; | |
127 | best = bestcount = 0; | |
128 | while (fgets(line, sizeof(line), f)) { | |
129 | linenum++; | |
130 | if (!parse_prime(linenum, line, &dhg)) | |
131 | continue; | |
108d362e | 132 | BN_clear_free(dhg.g); |
133 | BN_clear_free(dhg.p); | |
94ec8c6b | 134 | |
db1cd2f3 | 135 | if (dhg.size > max || dhg.size < min) |
136 | continue; | |
137 | ||
138 | if ((dhg.size > wantbits && dhg.size < best) || | |
139 | (dhg.size > best && best < wantbits)) { | |
94ec8c6b | 140 | best = dhg.size; |
141 | bestcount = 0; | |
142 | } | |
143 | if (dhg.size == best) | |
144 | bestcount++; | |
145 | } | |
826676b3 | 146 | rewind(f); |
94ec8c6b | 147 | |
148 | if (bestcount == 0) { | |
826676b3 | 149 | fclose(f); |
bbe88b6d | 150 | logit("WARNING: no suitable primes in %s", _PATH_DH_PRIMES); |
0875a0a2 | 151 | return (dh_new_group14()); |
94ec8c6b | 152 | } |
153 | ||
94ec8c6b | 154 | linenum = 0; |
155 | which = arc4random() % bestcount; | |
156 | while (fgets(line, sizeof(line), f)) { | |
157 | if (!parse_prime(linenum, line, &dhg)) | |
158 | continue; | |
a7ca6275 | 159 | if ((dhg.size > max || dhg.size < min) || |
160 | dhg.size != best || | |
161 | linenum++ != which) { | |
108d362e | 162 | BN_clear_free(dhg.g); |
163 | BN_clear_free(dhg.p); | |
94ec8c6b | 164 | continue; |
165 | } | |
166 | break; | |
167 | } | |
168 | fclose(f); | |
a7ca6275 | 169 | if (linenum != which+1) |
170 | fatal("WARNING: line %d disappeared in %s, giving up", | |
171 | which, _PATH_DH_PRIMES); | |
94ec8c6b | 172 | |
173 | return (dh_new_group(dhg.g, dhg.p)); | |
174 | } | |
03b8f8be | 175 | |
41e5bd9a | 176 | /* diffie-hellman-groupN-sha1 */ |
03b8f8be | 177 | |
178 | int | |
179 | dh_pub_is_valid(DH *dh, BIGNUM *dh_pub) | |
180 | { | |
181 | int i; | |
182 | int n = BN_num_bits(dh_pub); | |
183 | int bits_set = 0; | |
184 | ||
185 | if (dh_pub->neg) { | |
bbe88b6d | 186 | logit("invalid public DH value: negativ"); |
03b8f8be | 187 | return 0; |
188 | } | |
189 | for (i = 0; i <= n; i++) | |
190 | if (BN_is_bit_set(dh_pub, i)) | |
191 | bits_set++; | |
35efb24c | 192 | debug2("bits set: %d/%d", bits_set, BN_num_bits(dh->p)); |
03b8f8be | 193 | |
194 | /* if g==2 and bits_set==1 then computing log_g(dh_pub) is trivial */ | |
195 | if (bits_set > 1 && (BN_cmp(dh_pub, dh->p) == -1)) | |
196 | return 1; | |
bbe88b6d | 197 | logit("invalid public DH value (%d/%d)", bits_set, BN_num_bits(dh->p)); |
03b8f8be | 198 | return 0; |
199 | } | |
200 | ||
201 | void | |
202 | dh_gen_key(DH *dh, int need) | |
203 | { | |
e24bb7d5 | 204 | int i, bits_set, tries = 0; |
03b8f8be | 205 | |
206 | if (dh->p == NULL) | |
207 | fatal("dh_gen_key: dh->p == NULL"); | |
bb92e5cc | 208 | if (need > INT_MAX / 2 || 2 * need >= BN_num_bits(dh->p)) |
03b8f8be | 209 | fatal("dh_gen_key: group too small: %d (2*need %d)", |
210 | BN_num_bits(dh->p), 2*need); | |
211 | do { | |
212 | if (dh->priv_key != NULL) | |
108d362e | 213 | BN_clear_free(dh->priv_key); |
b775c6f2 | 214 | if ((dh->priv_key = BN_new()) == NULL) |
03b8f8be | 215 | fatal("dh_gen_key: BN_new failed"); |
216 | /* generate a 2*need bits random private exponent */ | |
83a9aa63 | 217 | if (!BN_rand(dh->priv_key, 2*need, 0, 0)) |
218 | fatal("dh_gen_key: BN_rand failed"); | |
03b8f8be | 219 | if (DH_generate_key(dh) == 0) |
220 | fatal("DH_generate_key"); | |
e24bb7d5 | 221 | for (i = 0, bits_set = 0; i <= BN_num_bits(dh->priv_key); i++) |
03b8f8be | 222 | if (BN_is_bit_set(dh->priv_key, i)) |
223 | bits_set++; | |
35efb24c | 224 | debug2("dh_gen_key: priv key bits set: %d/%d", |
03b8f8be | 225 | bits_set, BN_num_bits(dh->priv_key)); |
226 | if (tries++ > 10) | |
227 | fatal("dh_gen_key: too many bad keys: giving up"); | |
228 | } while (!dh_pub_is_valid(dh, dh->pub_key)); | |
229 | } | |
230 | ||
231 | DH * | |
232 | dh_new_group_asc(const char *gen, const char *modulus) | |
233 | { | |
234 | DH *dh; | |
03b8f8be | 235 | |
b775c6f2 | 236 | if ((dh = DH_new()) == NULL) |
237 | fatal("dh_new_group_asc: DH_new"); | |
03b8f8be | 238 | |
ec1f12d3 | 239 | if (BN_hex2bn(&dh->p, modulus) == 0) |
03b8f8be | 240 | fatal("BN_hex2bn p"); |
ec1f12d3 | 241 | if (BN_hex2bn(&dh->g, gen) == 0) |
03b8f8be | 242 | fatal("BN_hex2bn g"); |
243 | ||
244 | return (dh); | |
245 | } | |
246 | ||
247 | /* | |
248 | * This just returns the group, we still need to generate the exchange | |
249 | * value. | |
250 | */ | |
251 | ||
252 | DH * | |
253 | dh_new_group(BIGNUM *gen, BIGNUM *modulus) | |
254 | { | |
255 | DH *dh; | |
256 | ||
b775c6f2 | 257 | if ((dh = DH_new()) == NULL) |
258 | fatal("dh_new_group: DH_new"); | |
03b8f8be | 259 | dh->p = modulus; |
260 | dh->g = gen; | |
261 | ||
262 | return (dh); | |
263 | } | |
264 | ||
265 | DH * | |
266 | dh_new_group1(void) | |
267 | { | |
268 | static char *gen = "2", *group1 = | |
269 | "FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1" | |
270 | "29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD" | |
271 | "EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245" | |
272 | "E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED" | |
273 | "EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE65381" | |
274 | "FFFFFFFF" "FFFFFFFF"; | |
275 | ||
276 | return (dh_new_group_asc(gen, group1)); | |
277 | } | |
a5c9ffdb | 278 | |
41e5bd9a | 279 | DH * |
280 | dh_new_group14(void) | |
281 | { | |
282 | static char *gen = "2", *group14 = | |
283 | "FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1" | |
284 | "29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD" | |
285 | "EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245" | |
286 | "E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED" | |
287 | "EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D" | |
288 | "C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F" | |
289 | "83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D" | |
290 | "670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B" | |
291 | "E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9" | |
292 | "DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510" | |
293 | "15728E5A" "8AACAA68" "FFFFFFFF" "FFFFFFFF"; | |
294 | ||
295 | return (dh_new_group_asc(gen, group14)); | |
296 | } | |
297 | ||
a5c9ffdb | 298 | /* |
299 | * Estimates the group order for a Diffie-Hellman group that has an | |
300 | * attack complexity approximately the same as O(2**bits). Estimate | |
301 | * with: O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3))) | |
302 | */ | |
303 | ||
304 | int | |
305 | dh_estimate(int bits) | |
306 | { | |
307 | ||
b3c35b71 | 308 | if (bits <= 128) |
a5c9ffdb | 309 | return (1024); /* O(2**86) */ |
b3c35b71 | 310 | if (bits <= 192) |
a5c9ffdb | 311 | return (2048); /* O(2**116) */ |
312 | return (4096); /* O(2**156) */ | |
313 | } |