| /* $OpenBSD: dh.c,v 1.66 2018/08/04 00:55:06 djm 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 = NULL; |
| size_t linesize = 0; |
| int best, bestcount, which, 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 (getline(&line, &linesize, f) != -1) { |
| 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++; |
| } |
| free(line); |
| line = NULL; |
| linesize = 0; |
| 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 (getline(&line, &linesize, f) != -1) { |
| 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; |
| } |
| free(line); |
| line = NULL; |
| 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(const DH *dh, const BIGNUM *dh_pub) |
| { |
| int i; |
| int n = BN_num_bits(dh_pub); |
| int bits_set = 0; |
| BIGNUM *tmp; |
| const BIGNUM *dh_p; |
| |
| DH_get0_pqg(dh, &dh_p, NULL, NULL); |
| |
| if (BN_is_negative(dh_pub)) { |
| 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; |
| const BIGNUM *dh_p, *pub_key; |
| |
| DH_get0_pqg(dh, &dh_p, NULL, NULL); |
| |
| 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. |
| */ |
| if (!DH_set_length(dh, MINIMUM(need * 2, pbits - 1))) |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| |
| if (DH_generate_key(dh) == 0) |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| DH_get0_key(dh, &pub_key, NULL); |
| if (!dh_pub_is_valid(dh, pub_key)) |
| return SSH_ERR_INVALID_FORMAT; |
| return 0; |
| } |
| |
| DH * |
| dh_new_group_asc(const char *gen, const char *modulus) |
| { |
| DH *dh; |
| BIGNUM *dh_p = NULL, *dh_g = NULL; |
| |
| if ((dh = DH_new()) == NULL) |
| return NULL; |
| if (BN_hex2bn(&dh_p, modulus) == 0 || |
| BN_hex2bn(&dh_g, gen) == 0) |
| goto fail; |
| if (!DH_set0_pqg(dh, dh_p, NULL, dh_g)) |
| goto fail; |
| return dh; |
| fail: |
| DH_free(dh); |
| BN_clear_free(dh_p); |
| BN_clear_free(dh_g); |
| return NULL; |
| } |
| |
| /* |
| * 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; |
| if (!DH_set0_pqg(dh, modulus, NULL, gen)) { |
| DH_free(dh); |
| return NULL; |
| } |
| |
| 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 */ |