Annotation of src/usr.bin/ssh/dh.c, Revision 1.63
1.63 ! jsing 1: /* $OpenBSD: dh.c,v 1.62 2016/12/15 21:20:41 dtucker 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: */
1.39 stevesk 25:
1.1 provos 26:
27: #include <openssl/bn.h>
28: #include <openssl/dh.h>
1.38 stevesk 29:
1.59 dtucker 30: #include <errno.h>
1.41 stevesk 31: #include <stdio.h>
1.40 stevesk 32: #include <stdlib.h>
1.38 stevesk 33: #include <string.h>
1.55 deraadt 34: #include <limits.h>
1.1 provos 35:
36: #include "dh.h"
1.5 markus 37: #include "pathnames.h"
1.6 markus 38: #include "log.h"
39: #include "misc.h"
1.54 markus 40: #include "ssherr.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;
1.47 djm 48: long long n;
1.1 provos 49:
1.51 markus 50: dhg->p = dhg->g = NULL;
1.1 provos 51: cp = line;
1.32 djm 52: if ((arg = strdelim(&cp)) == NULL)
53: return 0;
1.1 provos 54: /* Ignore leading whitespace */
55: if (*arg == '\0')
56: arg = strdelim(&cp);
1.22 markus 57: if (!arg || !*arg || *arg == '#')
1.1 provos 58: return 0;
59:
60: /* time */
61: if (cp == NULL || *arg == '\0')
1.50 djm 62: goto truncated;
1.1 provos 63: arg = strsep(&cp, " "); /* type */
64: if (cp == NULL || *arg == '\0')
1.50 djm 65: goto truncated;
1.47 djm 66: /* Ensure this is a safe prime */
67: n = strtonum(arg, 0, 5, &errstr);
1.50 djm 68: if (errstr != NULL || n != MODULI_TYPE_SAFE) {
69: error("moduli:%d: type is not %d", linenum, MODULI_TYPE_SAFE);
1.47 djm 70: goto fail;
1.50 djm 71: }
1.1 provos 72: arg = strsep(&cp, " "); /* tests */
73: if (cp == NULL || *arg == '\0')
1.50 djm 74: goto truncated;
1.47 djm 75: /* Ensure prime has been tested and is not composite */
76: n = strtonum(arg, 0, 0x1f, &errstr);
77: if (errstr != NULL ||
1.50 djm 78: (n & MODULI_TESTS_COMPOSITE) || !(n & ~MODULI_TESTS_COMPOSITE)) {
79: error("moduli:%d: invalid moduli tests flag", linenum);
1.47 djm 80: goto fail;
1.50 djm 81: }
1.1 provos 82: arg = strsep(&cp, " "); /* tries */
83: if (cp == NULL || *arg == '\0')
1.50 djm 84: goto truncated;
1.47 djm 85: n = strtonum(arg, 0, 1<<30, &errstr);
1.50 djm 86: if (errstr != NULL || n == 0) {
87: error("moduli:%d: invalid primality trial count", linenum);
1.1 provos 88: goto fail;
1.50 djm 89: }
1.1 provos 90: strsize = strsep(&cp, " "); /* size */
91: if (cp == NULL || *strsize == '\0' ||
1.48 grunk 92: (dhg->size = (int)strtonum(strsize, 0, 64*1024, &errstr)) == 0 ||
1.50 djm 93: errstr) {
94: error("moduli:%d: invalid prime length", linenum);
1.1 provos 95: goto fail;
1.50 djm 96: }
1.9 provos 97: /* The whole group is one bit larger */
98: dhg->size++;
1.1 provos 99: gen = strsep(&cp, " "); /* gen */
100: if (cp == NULL || *gen == '\0')
1.50 djm 101: goto truncated;
1.1 provos 102: prime = strsep(&cp, " "); /* prime */
1.50 djm 103: if (cp != NULL || *prime == '\0') {
104: truncated:
105: error("moduli:%d: truncated", linenum);
1.1 provos 106: goto fail;
1.50 djm 107: }
1.1 provos 108:
1.54 markus 109: if ((dhg->g = BN_new()) == NULL ||
110: (dhg->p = BN_new()) == NULL) {
111: error("parse_prime: BN_new failed");
112: goto fail;
113: }
1.50 djm 114: if (BN_hex2bn(&dhg->g, gen) == 0) {
115: error("moduli:%d: could not parse generator value", linenum);
116: goto fail;
117: }
118: if (BN_hex2bn(&dhg->p, prime) == 0) {
119: error("moduli:%d: could not parse prime value", linenum);
120: goto fail;
121: }
122: if (BN_num_bits(dhg->p) != dhg->size) {
123: error("moduli:%d: prime has wrong size: actual %d listed %d",
124: linenum, BN_num_bits(dhg->p), dhg->size - 1);
125: goto fail;
126: }
127: if (BN_cmp(dhg->g, BN_value_one()) <= 0) {
128: error("moduli:%d: generator is invalid", linenum);
129: goto fail;
130: }
131: return 1;
1.10 provos 132:
1.1 provos 133: fail:
1.63 ! jsing 134: BN_clear_free(dhg->g);
! 135: BN_clear_free(dhg->p);
1.50 djm 136: dhg->g = dhg->p = NULL;
137: return 0;
1.1 provos 138: }
139:
140: DH *
1.9 provos 141: choose_dh(int min, int wantbits, int max)
1.1 provos 142: {
143: FILE *f;
1.28 dtucker 144: char line[4096];
1.1 provos 145: int best, bestcount, which;
146: int linenum;
147: struct dhgroup dhg;
148:
1.59 dtucker 149: if ((f = fopen(_PATH_DH_MODULI, "r")) == NULL) {
1.62 dtucker 150: logit("WARNING: could not open %s (%s), using fixed modulus",
1.59 dtucker 151: _PATH_DH_MODULI, strerror(errno));
1.57 dtucker 152: return (dh_new_group_fallback(max));
1.1 provos 153: }
154:
155: linenum = 0;
156: best = bestcount = 0;
157: while (fgets(line, sizeof(line), f)) {
158: linenum++;
159: if (!parse_prime(linenum, line, &dhg))
160: continue;
1.19 markus 161: BN_clear_free(dhg.g);
162: BN_clear_free(dhg.p);
1.1 provos 163:
1.9 provos 164: if (dhg.size > max || dhg.size < min)
165: continue;
166:
167: if ((dhg.size > wantbits && dhg.size < best) ||
168: (dhg.size > best && best < wantbits)) {
1.1 provos 169: best = dhg.size;
170: bestcount = 0;
171: }
172: if (dhg.size == best)
173: bestcount++;
174: }
1.16 provos 175: rewind(f);
1.1 provos 176:
177: if (bestcount == 0) {
1.16 provos 178: fclose(f);
1.59 dtucker 179: logit("WARNING: no suitable primes in %s", _PATH_DH_MODULI);
1.57 dtucker 180: return (dh_new_group_fallback(max));
1.1 provos 181: }
182:
183: linenum = 0;
1.46 djm 184: which = arc4random_uniform(bestcount);
1.1 provos 185: while (fgets(line, sizeof(line), f)) {
186: if (!parse_prime(linenum, line, &dhg))
1.9 provos 187: continue;
1.13 markus 188: if ((dhg.size > max || dhg.size < min) ||
189: dhg.size != best ||
190: linenum++ != which) {
1.19 markus 191: BN_clear_free(dhg.g);
192: BN_clear_free(dhg.p);
1.1 provos 193: continue;
194: }
195: break;
196: }
197: fclose(f);
1.54 markus 198: if (linenum != which+1) {
199: logit("WARNING: line %d disappeared in %s, giving up",
1.59 dtucker 200: which, _PATH_DH_MODULI);
1.57 dtucker 201: return (dh_new_group_fallback(max));
1.54 markus 202: }
1.1 provos 203:
204: return (dh_new_group(dhg.g, dhg.p));
1.11 markus 205: }
206:
1.30 djm 207: /* diffie-hellman-groupN-sha1 */
1.11 markus 208:
209: int
210: dh_pub_is_valid(DH *dh, BIGNUM *dh_pub)
211: {
212: int i;
213: int n = BN_num_bits(dh_pub);
214: int bits_set = 0;
1.36 djm 215: BIGNUM *tmp;
1.11 markus 216:
217: if (dh_pub->neg) {
1.45 ray 218: logit("invalid public DH value: negative");
1.11 markus 219: return 0;
220: }
1.36 djm 221: if (BN_cmp(dh_pub, BN_value_one()) != 1) { /* pub_exp <= 1 */
222: logit("invalid public DH value: <= 1");
223: return 0;
224: }
225:
1.45 ray 226: if ((tmp = BN_new()) == NULL) {
227: error("%s: BN_new failed", __func__);
228: return 0;
229: }
1.36 djm 230: if (!BN_sub(tmp, dh->p, BN_value_one()) ||
231: BN_cmp(dh_pub, tmp) != -1) { /* pub_exp > p-2 */
232: BN_clear_free(tmp);
233: logit("invalid public DH value: >= p-1");
234: return 0;
235: }
236: BN_clear_free(tmp);
237:
1.11 markus 238: for (i = 0; i <= n; i++)
239: if (BN_is_bit_set(dh_pub, i))
240: bits_set++;
1.23 markus 241: debug2("bits set: %d/%d", bits_set, BN_num_bits(dh->p));
1.11 markus 242:
1.58 djm 243: /*
244: * if g==2 and bits_set==1 then computing log_g(dh_pub) is trivial
245: */
246: if (bits_set < 4) {
247: logit("invalid public DH value (%d/%d)",
248: bits_set, BN_num_bits(dh->p));
249: return 0;
250: }
251: return 1;
1.11 markus 252: }
253:
1.54 markus 254: int
1.11 markus 255: dh_gen_key(DH *dh, int need)
256: {
1.53 djm 257: int pbits;
1.11 markus 258:
1.54 markus 259: if (need < 0 || dh->p == NULL ||
260: (pbits = BN_num_bits(dh->p)) <= 0 ||
1.56 djm 261: need > INT_MAX / 2 || 2 * need > pbits)
1.54 markus 262: return SSH_ERR_INVALID_ARGUMENT;
1.58 djm 263: if (need < 256)
264: need = 256;
265: /*
266: * Pollard Rho, Big step/Little Step attacks are O(sqrt(n)),
267: * so double requested need here.
268: */
1.61 deraadt 269: dh->length = MINIMUM(need * 2, pbits - 1);
1.54 markus 270: if (DH_generate_key(dh) == 0 ||
271: !dh_pub_is_valid(dh, dh->pub_key)) {
272: BN_clear_free(dh->priv_key);
273: return SSH_ERR_LIBCRYPTO_ERROR;
274: }
275: return 0;
1.11 markus 276: }
277:
278: DH *
279: dh_new_group_asc(const char *gen, const char *modulus)
280: {
281: DH *dh;
282:
1.18 markus 283: if ((dh = DH_new()) == NULL)
1.54 markus 284: return NULL;
285: if (BN_hex2bn(&dh->p, modulus) == 0 ||
286: BN_hex2bn(&dh->g, gen) == 0) {
287: DH_free(dh);
288: return NULL;
289: }
1.11 markus 290: return (dh);
291: }
292:
293: /*
294: * This just returns the group, we still need to generate the exchange
295: * value.
296: */
297:
298: DH *
299: dh_new_group(BIGNUM *gen, BIGNUM *modulus)
300: {
301: DH *dh;
302:
1.18 markus 303: if ((dh = DH_new()) == NULL)
1.54 markus 304: return NULL;
1.11 markus 305: dh->p = modulus;
306: dh->g = gen;
307:
308: return (dh);
309: }
310:
1.60 djm 311: /* rfc2409 "Second Oakley Group" (1024 bits) */
1.11 markus 312: DH *
313: dh_new_group1(void)
314: {
315: static char *gen = "2", *group1 =
316: "FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
317: "29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
318: "EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
319: "E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
320: "EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE65381"
321: "FFFFFFFF" "FFFFFFFF";
322:
323: return (dh_new_group_asc(gen, group1));
1.30 djm 324: }
325:
1.60 djm 326: /* rfc3526 group 14 "2048-bit MODP Group" */
1.30 djm 327: DH *
328: dh_new_group14(void)
329: {
330: static char *gen = "2", *group14 =
331: "FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
332: "29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
333: "EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
334: "E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
335: "EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D"
336: "C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
337: "83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
338: "670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B"
339: "E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9"
340: "DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510"
341: "15728E5A" "8AACAA68" "FFFFFFFF" "FFFFFFFF";
342:
343: return (dh_new_group_asc(gen, group14));
1.57 dtucker 344: }
345:
1.60 djm 346: /* rfc3526 group 16 "4096-bit MODP Group" */
1.57 dtucker 347: DH *
1.60 djm 348: dh_new_group16(void)
1.57 dtucker 349: {
350: static char *gen = "2", *group16 =
351: "FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
352: "29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
353: "EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
354: "E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
355: "EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D"
356: "C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
357: "83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
358: "670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B"
359: "E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9"
360: "DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510"
361: "15728E5A" "8AAAC42D" "AD33170D" "04507A33" "A85521AB" "DF1CBA64"
362: "ECFB8504" "58DBEF0A" "8AEA7157" "5D060C7D" "B3970F85" "A6E1E4C7"
363: "ABF5AE8C" "DB0933D7" "1E8C94E0" "4A25619D" "CEE3D226" "1AD2EE6B"
364: "F12FFA06" "D98A0864" "D8760273" "3EC86A64" "521F2B18" "177B200C"
365: "BBE11757" "7A615D6C" "770988C0" "BAD946E2" "08E24FA0" "74E5AB31"
366: "43DB5BFC" "E0FD108E" "4B82D120" "A9210801" "1A723C12" "A787E6D7"
367: "88719A10" "BDBA5B26" "99C32718" "6AF4E23C" "1A946834" "B6150BDA"
368: "2583E9CA" "2AD44CE8" "DBBBC2DB" "04DE8EF9" "2E8EFC14" "1FBECAA6"
369: "287C5947" "4E6BC05D" "99B2964F" "A090C3A2" "233BA186" "515BE7ED"
370: "1F612970" "CEE2D7AF" "B81BDD76" "2170481C" "D0069127" "D5B05AA9"
371: "93B4EA98" "8D8FDDC1" "86FFB7DC" "90A6C08F" "4DF435C9" "34063199"
372: "FFFFFFFF" "FFFFFFFF";
373:
1.60 djm 374: return (dh_new_group_asc(gen, group16));
375: }
376:
377: /* rfc3526 group 18 "8192-bit MODP Group" */
378: DH *
379: dh_new_group18(void)
380: {
381: static char *gen = "2", *group16 =
382: "FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
383: "29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
384: "EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
385: "E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
386: "EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D"
387: "C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
388: "83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
389: "670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B"
390: "E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9"
391: "DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510"
392: "15728E5A" "8AAAC42D" "AD33170D" "04507A33" "A85521AB" "DF1CBA64"
393: "ECFB8504" "58DBEF0A" "8AEA7157" "5D060C7D" "B3970F85" "A6E1E4C7"
394: "ABF5AE8C" "DB0933D7" "1E8C94E0" "4A25619D" "CEE3D226" "1AD2EE6B"
395: "F12FFA06" "D98A0864" "D8760273" "3EC86A64" "521F2B18" "177B200C"
396: "BBE11757" "7A615D6C" "770988C0" "BAD946E2" "08E24FA0" "74E5AB31"
397: "43DB5BFC" "E0FD108E" "4B82D120" "A9210801" "1A723C12" "A787E6D7"
398: "88719A10" "BDBA5B26" "99C32718" "6AF4E23C" "1A946834" "B6150BDA"
399: "2583E9CA" "2AD44CE8" "DBBBC2DB" "04DE8EF9" "2E8EFC14" "1FBECAA6"
400: "287C5947" "4E6BC05D" "99B2964F" "A090C3A2" "233BA186" "515BE7ED"
401: "1F612970" "CEE2D7AF" "B81BDD76" "2170481C" "D0069127" "D5B05AA9"
402: "93B4EA98" "8D8FDDC1" "86FFB7DC" "90A6C08F" "4DF435C9" "34028492"
403: "36C3FAB4" "D27C7026" "C1D4DCB2" "602646DE" "C9751E76" "3DBA37BD"
404: "F8FF9406" "AD9E530E" "E5DB382F" "413001AE" "B06A53ED" "9027D831"
405: "179727B0" "865A8918" "DA3EDBEB" "CF9B14ED" "44CE6CBA" "CED4BB1B"
406: "DB7F1447" "E6CC254B" "33205151" "2BD7AF42" "6FB8F401" "378CD2BF"
407: "5983CA01" "C64B92EC" "F032EA15" "D1721D03" "F482D7CE" "6E74FEF6"
408: "D55E702F" "46980C82" "B5A84031" "900B1C9E" "59E7C97F" "BEC7E8F3"
409: "23A97A7E" "36CC88BE" "0F1D45B7" "FF585AC5" "4BD407B2" "2B4154AA"
410: "CC8F6D7E" "BF48E1D8" "14CC5ED2" "0F8037E0" "A79715EE" "F29BE328"
411: "06A1D58B" "B7C5DA76" "F550AA3D" "8A1FBFF0" "EB19CCB1" "A313D55C"
412: "DA56C9EC" "2EF29632" "387FE8D7" "6E3C0468" "043E8F66" "3F4860EE"
413: "12BF2D5B" "0B7474D6" "E694F91E" "6DBE1159" "74A3926F" "12FEE5E4"
414: "38777CB6" "A932DF8C" "D8BEC4D0" "73B931BA" "3BC832B6" "8D9DD300"
415: "741FA7BF" "8AFC47ED" "2576F693" "6BA42466" "3AAB639C" "5AE4F568"
416: "3423B474" "2BF1C978" "238F16CB" "E39D652D" "E3FDB8BE" "FC848AD9"
417: "22222E04" "A4037C07" "13EB57A8" "1A23F0C7" "3473FC64" "6CEA306B"
418: "4BCBC886" "2F8385DD" "FA9D4B7F" "A2C087E8" "79683303" "ED5BDD3A"
419: "062B3CF5" "B3A278A6" "6D2A13F8" "3F44F82D" "DF310EE0" "74AB6A36"
420: "4597E899" "A0255DC1" "64F31CC5" "0846851D" "F9AB4819" "5DED7EA1"
421: "B1D510BD" "7EE74D73" "FAF36BC3" "1ECFA268" "359046F4" "EB879F92"
422: "4009438B" "481C6CD7" "889A002E" "D5EE382B" "C9190DA6" "FC026E47"
423: "9558E447" "5677E9AA" "9E3050E2" "765694DF" "C81F56E8" "80B96E71"
424: "60C980DD" "98EDD3DF" "FFFFFFFF" "FFFFFFFF";
425:
426: return (dh_new_group_asc(gen, group16));
427: }
428:
429: /* Select fallback group used by DH-GEX if moduli file cannot be read. */
430: DH *
431: dh_new_group_fallback(int max)
432: {
433: debug3("%s: requested max size %d", __func__, max);
434: if (max < 3072) {
435: debug3("using 2k bit group 14");
1.57 dtucker 436: return dh_new_group14();
1.60 djm 437: } else if (max < 6144) {
438: debug3("using 4k bit group 16");
439: return dh_new_group16();
1.57 dtucker 440: }
1.60 djm 441: debug3("using 8k bit group 18");
442: return dh_new_group18();
1.12 markus 443: }
444:
445: /*
446: * Estimates the group order for a Diffie-Hellman group that has an
1.52 dtucker 447: * attack complexity approximately the same as O(2**bits).
448: * Values from NIST Special Publication 800-57: Recommendation for Key
449: * Management Part 1 (rev 3) limited by the recommended maximum value
450: * from RFC4419 section 3.
1.12 markus 451: */
1.54 markus 452: u_int
1.12 markus 453: dh_estimate(int bits)
454: {
1.52 dtucker 455: if (bits <= 112)
456: return 2048;
1.26 markus 457: if (bits <= 128)
1.52 dtucker 458: return 3072;
1.26 markus 459: if (bits <= 192)
1.52 dtucker 460: return 7680;
461: return 8192;
1.1 provos 462: }
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