Annotation of src/usr.bin/ssh/dh.c, Revision 1.35
1.35 ! deraadt 1: /* $OpenBSD: dh.c,v 1.34 2006/03/25 13:17:01 djm Exp $ */
1.1 provos 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"
27:
28: #include "xmalloc.h"
29:
30: #include <openssl/bn.h>
31: #include <openssl/dh.h>
32: #include <openssl/evp.h>
33:
34: #include "buffer.h"
1.6 markus 35: #include "cipher.h"
1.1 provos 36: #include "kex.h"
37: #include "dh.h"
1.5 markus 38: #include "pathnames.h"
1.6 markus 39: #include "log.h"
40: #include "misc.h"
1.1 provos 41:
1.17 itojun 42: static int
1.1 provos 43: parse_prime(int linenum, char *line, struct dhgroup *dhg)
44: {
45: char *cp, *arg;
46: char *strsize, *gen, *prime;
1.35 ! deraadt 47: const char *errstr = NULL;
1.1 provos 48:
49: cp = line;
1.32 djm 50: if ((arg = strdelim(&cp)) == NULL)
51: return 0;
1.1 provos 52: /* Ignore leading whitespace */
53: if (*arg == '\0')
54: arg = strdelim(&cp);
1.22 markus 55: if (!arg || !*arg || *arg == '#')
1.1 provos 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' ||
1.35 ! deraadt 72: (dhg->size = (u_int)strtonum(strsize, 0, 64*1024, &errstr)) == 0 ||
! 73: errstr)
1.1 provos 74: goto fail;
1.9 provos 75: /* The whole group is one bit larger */
76: dhg->size++;
1.1 provos 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:
1.18 markus 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");
1.14 markus 88: if (BN_hex2bn(&dhg->g, gen) == 0)
1.10 provos 89: goto failclean;
90:
1.14 markus 91: if (BN_hex2bn(&dhg->p, prime) == 0)
1.10 provos 92: goto failclean;
93:
94: if (BN_num_bits(dhg->p) != dhg->size)
1.27 dtucker 95: goto failclean;
96:
97: if (BN_is_zero(dhg->g) || BN_is_one(dhg->g))
1.10 provos 98: goto failclean;
1.1 provos 99:
100: return (1);
1.10 provos 101:
102: failclean:
1.19 markus 103: BN_clear_free(dhg->g);
104: BN_clear_free(dhg->p);
1.1 provos 105: fail:
1.7 millert 106: error("Bad prime description in line %d", linenum);
1.1 provos 107: return (0);
108: }
109:
110: DH *
1.9 provos 111: choose_dh(int min, int wantbits, int max)
1.1 provos 112: {
113: FILE *f;
1.28 dtucker 114: char line[4096];
1.1 provos 115: int best, bestcount, which;
116: int linenum;
117: struct dhgroup dhg;
118:
1.15 provos 119: if ((f = fopen(_PATH_DH_MODULI, "r")) == NULL &&
120: (f = fopen(_PATH_DH_PRIMES, "r")) == NULL) {
1.30 djm 121: logit("WARNING: %s does not exist, using fixed modulus",
122: _PATH_DH_MODULI);
123: return (dh_new_group14());
1.1 provos 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;
1.19 markus 132: BN_clear_free(dhg.g);
133: BN_clear_free(dhg.p);
1.1 provos 134:
1.9 provos 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)) {
1.1 provos 140: best = dhg.size;
141: bestcount = 0;
142: }
143: if (dhg.size == best)
144: bestcount++;
145: }
1.16 provos 146: rewind(f);
1.1 provos 147:
148: if (bestcount == 0) {
1.16 provos 149: fclose(f);
1.24 itojun 150: logit("WARNING: no suitable primes in %s", _PATH_DH_PRIMES);
1.31 djm 151: return (dh_new_group14());
1.1 provos 152: }
153:
154: linenum = 0;
155: which = arc4random() % bestcount;
156: while (fgets(line, sizeof(line), f)) {
157: if (!parse_prime(linenum, line, &dhg))
1.9 provos 158: continue;
1.13 markus 159: if ((dhg.size > max || dhg.size < min) ||
160: dhg.size != best ||
161: linenum++ != which) {
1.19 markus 162: BN_clear_free(dhg.g);
163: BN_clear_free(dhg.p);
1.1 provos 164: continue;
165: }
166: break;
167: }
168: fclose(f);
1.13 markus 169: if (linenum != which+1)
170: fatal("WARNING: line %d disappeared in %s, giving up",
171: which, _PATH_DH_PRIMES);
1.1 provos 172:
173: return (dh_new_group(dhg.g, dhg.p));
1.11 markus 174: }
175:
1.30 djm 176: /* diffie-hellman-groupN-sha1 */
1.11 markus 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) {
1.24 itojun 186: logit("invalid public DH value: negativ");
1.11 markus 187: return 0;
188: }
189: for (i = 0; i <= n; i++)
190: if (BN_is_bit_set(dh_pub, i))
191: bits_set++;
1.23 markus 192: debug2("bits set: %d/%d", bits_set, BN_num_bits(dh->p));
1.11 markus 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;
1.24 itojun 197: logit("invalid public DH value (%d/%d)", bits_set, BN_num_bits(dh->p));
1.11 markus 198: return 0;
199: }
200:
201: void
202: dh_gen_key(DH *dh, int need)
203: {
1.29 dtucker 204: int i, bits_set, tries = 0;
1.11 markus 205:
206: if (dh->p == NULL)
207: fatal("dh_gen_key: dh->p == NULL");
1.25 miod 208: if (need > INT_MAX / 2 || 2 * need >= BN_num_bits(dh->p))
1.11 markus 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)
1.19 markus 213: BN_clear_free(dh->priv_key);
1.18 markus 214: if ((dh->priv_key = BN_new()) == NULL)
1.11 markus 215: fatal("dh_gen_key: BN_new failed");
216: /* generate a 2*need bits random private exponent */
1.21 markus 217: if (!BN_rand(dh->priv_key, 2*need, 0, 0))
218: fatal("dh_gen_key: BN_rand failed");
1.11 markus 219: if (DH_generate_key(dh) == 0)
220: fatal("DH_generate_key");
1.29 dtucker 221: for (i = 0, bits_set = 0; i <= BN_num_bits(dh->priv_key); i++)
1.11 markus 222: if (BN_is_bit_set(dh->priv_key, i))
223: bits_set++;
1.23 markus 224: debug2("dh_gen_key: priv key bits set: %d/%d",
1.11 markus 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;
235:
1.18 markus 236: if ((dh = DH_new()) == NULL)
237: fatal("dh_new_group_asc: DH_new");
1.11 markus 238:
1.14 markus 239: if (BN_hex2bn(&dh->p, modulus) == 0)
1.11 markus 240: fatal("BN_hex2bn p");
1.14 markus 241: if (BN_hex2bn(&dh->g, gen) == 0)
1.11 markus 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:
1.18 markus 257: if ((dh = DH_new()) == NULL)
258: fatal("dh_new_group: DH_new");
1.11 markus 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));
1.30 djm 277: }
278:
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));
1.12 markus 296: }
297:
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:
1.26 markus 308: if (bits <= 128)
1.12 markus 309: return (1024); /* O(2**86) */
1.26 markus 310: if (bits <= 192)
1.12 markus 311: return (2048); /* O(2**116) */
312: return (4096); /* O(2**156) */
1.1 provos 313: }
![[BACK]](/icons/back.gif){kind=icon}
Return to dh.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh