| /* $OpenBSD: dh.c,v 1.49 2011/12/07 05:44:38 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" | 
 |  | 
 | #include <sys/param.h> | 
 |  | 
 | #include <openssl/bn.h> | 
 | #include <openssl/dh.h> | 
 |  | 
 | #include <stdarg.h> | 
 | #include <stdio.h> | 
 | #include <stdlib.h> | 
 | #include <string.h> | 
 |  | 
 | #include "dh.h" | 
 | #include "pathnames.h" | 
 | #include "log.h" | 
 | #include "misc.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; | 
 |  | 
 | 	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 fail; | 
 | 	arg = strsep(&cp, " "); /* type */ | 
 | 	if (cp == NULL || *arg == '\0') | 
 | 		goto fail; | 
 | 	/* Ensure this is a safe prime */ | 
 | 	n = strtonum(arg, 0, 5, &errstr); | 
 | 	if (errstr != NULL || n != MODULI_TYPE_SAFE) | 
 | 		goto fail; | 
 | 	arg = strsep(&cp, " "); /* tests */ | 
 | 	if (cp == NULL || *arg == '\0') | 
 | 		goto fail; | 
 | 	/* 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)) | 
 | 		goto fail; | 
 | 	arg = strsep(&cp, " "); /* tries */ | 
 | 	if (cp == NULL || *arg == '\0') | 
 | 		goto fail; | 
 | 	n = strtonum(arg, 0, 1<<30, &errstr); | 
 | 	if (errstr != NULL || n == 0) | 
 | 		goto fail; | 
 | 	strsize = strsep(&cp, " "); /* size */ | 
 | 	if (cp == NULL || *strsize == '\0' || | 
 | 	    (dhg->size = (int)strtonum(strsize, 0, 64*1024, &errstr)) == 0 || | 
 | 	    errstr) | 
 | 		goto fail; | 
 | 	/* The whole group is one bit larger */ | 
 | 	dhg->size++; | 
 | 	gen = strsep(&cp, " "); /* gen */ | 
 | 	if (cp == NULL || *gen == '\0') | 
 | 		goto fail; | 
 | 	prime = strsep(&cp, " "); /* prime */ | 
 | 	if (cp != NULL || *prime == '\0') | 
 | 		goto fail; | 
 |  | 
 | 	if ((dhg->g = BN_new()) == NULL) | 
 | 		fatal("parse_prime: BN_new failed"); | 
 | 	if ((dhg->p = BN_new()) == NULL) | 
 | 		fatal("parse_prime: BN_new failed"); | 
 | 	if (BN_hex2bn(&dhg->g, gen) == 0) | 
 | 		goto failclean; | 
 |  | 
 | 	if (BN_hex2bn(&dhg->p, prime) == 0) | 
 | 		goto failclean; | 
 |  | 
 | 	if (BN_num_bits(dhg->p) != dhg->size) | 
 | 		goto failclean; | 
 |  | 
 | 	if (BN_is_zero(dhg->g) || BN_is_one(dhg->g)) | 
 | 		goto failclean; | 
 |  | 
 | 	return (1); | 
 |  | 
 |  failclean: | 
 | 	BN_clear_free(dhg->g); | 
 | 	BN_clear_free(dhg->p); | 
 |  fail: | 
 | 	error("Bad prime description in line %d", linenum); | 
 | 	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 && | 
 | 	    (f = fopen(_PATH_DH_PRIMES, "r")) == NULL) { | 
 | 		logit("WARNING: %s does not exist, using fixed modulus", | 
 | 		    _PATH_DH_MODULI); | 
 | 		return (dh_new_group14()); | 
 | 	} | 
 |  | 
 | 	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_PRIMES); | 
 | 		return (dh_new_group14()); | 
 | 	} | 
 |  | 
 | 	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) | 
 | 		fatal("WARNING: line %d disappeared in %s, giving up", | 
 | 		    which, _PATH_DH_PRIMES); | 
 |  | 
 | 	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 > 1) | 
 | 		return 1; | 
 |  | 
 | 	logit("invalid public DH value (%d/%d)", bits_set, BN_num_bits(dh->p)); | 
 | 	return 0; | 
 | } | 
 |  | 
 | void | 
 | dh_gen_key(DH *dh, int need) | 
 | { | 
 | 	int i, bits_set, tries = 0; | 
 |  | 
 | 	if (need < 0) | 
 | 		fatal("dh_gen_key: need < 0"); | 
 | 	if (dh->p == NULL) | 
 | 		fatal("dh_gen_key: dh->p == NULL"); | 
 | 	if (need > INT_MAX / 2 || 2 * need >= BN_num_bits(dh->p)) | 
 | 		fatal("dh_gen_key: group too small: %d (2*need %d)", | 
 | 		    BN_num_bits(dh->p), 2*need); | 
 | 	do { | 
 | 		if (dh->priv_key != NULL) | 
 | 			BN_clear_free(dh->priv_key); | 
 | 		if ((dh->priv_key = BN_new()) == NULL) | 
 | 			fatal("dh_gen_key: BN_new failed"); | 
 | 		/* generate a 2*need bits random private exponent */ | 
 | 		if (!BN_rand(dh->priv_key, 2*need, 0, 0)) | 
 | 			fatal("dh_gen_key: BN_rand failed"); | 
 | 		if (DH_generate_key(dh) == 0) | 
 | 			fatal("DH_generate_key"); | 
 | 		for (i = 0, bits_set = 0; i <= BN_num_bits(dh->priv_key); i++) | 
 | 			if (BN_is_bit_set(dh->priv_key, i)) | 
 | 				bits_set++; | 
 | 		debug2("dh_gen_key: priv key bits set: %d/%d", | 
 | 		    bits_set, BN_num_bits(dh->priv_key)); | 
 | 		if (tries++ > 10) | 
 | 			fatal("dh_gen_key: too many bad keys: giving up"); | 
 | 	} while (!dh_pub_is_valid(dh, dh->pub_key)); | 
 | } | 
 |  | 
 | DH * | 
 | dh_new_group_asc(const char *gen, const char *modulus) | 
 | { | 
 | 	DH *dh; | 
 |  | 
 | 	if ((dh = DH_new()) == NULL) | 
 | 		fatal("dh_new_group_asc: DH_new"); | 
 |  | 
 | 	if (BN_hex2bn(&dh->p, modulus) == 0) | 
 | 		fatal("BN_hex2bn p"); | 
 | 	if (BN_hex2bn(&dh->g, gen) == 0) | 
 | 		fatal("BN_hex2bn g"); | 
 |  | 
 | 	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) | 
 | 		fatal("dh_new_group: DH_new"); | 
 | 	dh->p = modulus; | 
 | 	dh->g = gen; | 
 |  | 
 | 	return (dh); | 
 | } | 
 |  | 
 | 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)); | 
 | } | 
 |  | 
 | 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)); | 
 | } | 
 |  | 
 | /* | 
 |  * Estimates the group order for a Diffie-Hellman group that has an | 
 |  * attack complexity approximately the same as O(2**bits).  Estimate | 
 |  * with:  O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3))) | 
 |  */ | 
 |  | 
 | int | 
 | dh_estimate(int bits) | 
 | { | 
 |  | 
 | 	if (bits <= 128) | 
 | 		return (1024);	/* O(2**86) */ | 
 | 	if (bits <= 192) | 
 | 		return (2048);	/* O(2**116) */ | 
 | 	return (4096);		/* O(2**156) */ | 
 | } |