[openssh.git] / dh.c

/*
 * 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"
RCSID("$OpenBSD: dh.c,v 1.2 2000/10/11 20:11:35 markus Exp $");

#include "xmalloc.h"

#include <openssl/bn.h>
#include <openssl/dh.h>
#include <openssl/evp.h>

#include "ssh.h"
#include "buffer.h"
#include "kex.h"
#include "dh.h"

int
parse_prime(int linenum, char *line, struct dhgroup *dhg)
{
	char *cp, *arg;
	char *strsize, *gen, *prime;

	cp = line;
	arg = strdelim(&cp);
	/* Ignore leading whitespace */
	if (*arg == '\0')
		arg = strdelim(&cp);
	if (!*arg || *arg == '#')
		return 0;

	/* time */
	if (cp == NULL || *arg == '\0')
		goto fail;
	arg = strsep(&cp, " "); /* type */
	if (cp == NULL || *arg == '\0')
		goto fail;
	arg = strsep(&cp, " "); /* tests */
	if (cp == NULL || *arg == '\0')
		goto fail;
	arg = strsep(&cp, " "); /* tries */
	if (cp == NULL || *arg == '\0')
		goto fail;
	strsize = strsep(&cp, " "); /* size */
	if (cp == NULL || *strsize == '\0' ||
	    (dhg->size = atoi(strsize)) == 0)
		goto fail;
	gen = strsep(&cp, " "); /* gen */
	if (cp == NULL || *gen == '\0')
		goto fail;
	prime = strsep(&cp, " "); /* prime */
	if (cp != NULL || *prime == '\0')
		goto fail;

	dhg->g = BN_new();
	if (BN_hex2bn(&dhg->g, gen) < 0) {
		BN_free(dhg->g);
		goto fail;
	}
	dhg->p = BN_new();
	if (BN_hex2bn(&dhg->p, prime) < 0) {
		BN_free(dhg->g);
		BN_free(dhg->p);
		goto fail;
	}

	return (1);
 fail:
	fprintf(stderr, "Bad prime description in line %d\n", linenum);
	return (0);
}

DH *
choose_dh(int minbits)
{
	FILE *f;
	char line[1024];
	int best, bestcount, which;
	int linenum;
	struct dhgroup dhg;

	f = fopen(DH_PRIMES, "r");
	if (!f) {
		perror(DH_PRIMES);
		log("WARNING: %s does not exist, using old prime", DH_PRIMES);
		return (dh_new_group1());
	}

	linenum = 0;
	best = bestcount = 0;
	while (fgets(line, sizeof(line), f)) {
		linenum++;
		if (!parse_prime(linenum, line, &dhg))
			continue;
		BN_free(dhg.g);
		BN_free(dhg.p);

		if ((dhg.size > minbits && dhg.size < best) ||
		    (dhg.size > best && best < minbits)) {
			best = dhg.size;
			bestcount = 0;
		}
		if (dhg.size == best)
			bestcount++;
	}
	fclose (f);

	if (bestcount == 0) {
		log("WARNING: no primes in %s, using old prime", DH_PRIMES);
		return (dh_new_group1());
	}

	f = fopen(DH_PRIMES, "r");
	if (!f) {
		perror(DH_PRIMES);
		exit(1);
	}

	linenum = 0;
	which = arc4random() % bestcount;
	while (fgets(line, sizeof(line), f)) {
		if (!parse_prime(linenum, line, &dhg))
			continue;
		if (dhg.size != best)
			continue;
		if (linenum++ != which) {
			BN_free(dhg.g);
			BN_free(dhg.p);
			continue;
		}
		break;
	}
	fclose(f);

	return (dh_new_group(dhg.g, dhg.p));
}
Commit	Line	Data
94ec8c6b	1	/*
	2	* Copyright (c) 2000 Niels Provos. All rights reserved.
	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	* 1. Redistributions of source code must retain the above copyright
	8	* notice, this list of conditions and the following disclaimer.
	9	* 2. Redistributions in binary form must reproduce the above copyright
	10	* notice, this list of conditions and the following disclaimer in the
	11	* documentation and/or other materials provided with the distribution.
	12	*
	13	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	14	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	15	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	16	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	17	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	18	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	19	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	20	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	21	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	22	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	23	*/
	24
	25	#include "includes.h"
	26	RCSID("$OpenBSD: dh.c,v 1.2 2000/10/11 20:11:35 markus Exp $");
	27
	28	#include "xmalloc.h"
	29
	30	#include <openssl/bn.h>
	31	#include <openssl/dh.h>
	32	#include <openssl/evp.h>
	33
	34	#include "ssh.h"
	35	#include "buffer.h"
	36	#include "kex.h"
	37	#include "dh.h"
	38
	39	int
	40	parse_prime(int linenum, char line, struct dhgroup dhg)
	41	{
	42	char cp, arg;
	43	char strsize, gen, *prime;
	44
	45	cp = line;
	46	arg = strdelim(&cp);
	47	/* Ignore leading whitespace */
	48	if (*arg == '\0')
	49	arg = strdelim(&cp);
	50	if (!arg \|\| arg == '#')
	51	return 0;
	52
	53	/* time */
	54	if (cp == NULL \|\| *arg == '\0')
	55	goto fail;
	56	arg = strsep(&cp, " "); /* type */
	57	if (cp == NULL \|\| *arg == '\0')
	58	goto fail;
	59	arg = strsep(&cp, " "); /* tests */
	60	if (cp == NULL \|\| *arg == '\0')
	61	goto fail;
	62	arg = strsep(&cp, " "); /* tries */
	63	if (cp == NULL \|\| *arg == '\0')
	64	goto fail;
65	strsize = strsep(&cp, " "); /* size */
66	if (cp == NULL \|\| *strsize == '\0' \|\|
67	(dhg->size = atoi(strsize)) == 0)
68	goto fail;
69	gen = strsep(&cp, " "); /* gen */
70	if (cp == NULL \|\| *gen == '\0')
71	goto fail;
72	prime = strsep(&cp, " "); /* prime */
73	if (cp != NULL \|\| *prime == '\0')
74	goto fail;
75
76	dhg->g = BN_new();
77	if (BN_hex2bn(&dhg->g, gen) < 0) {
78	BN_free(dhg->g);
79	goto fail;
80	}
81	dhg->p = BN_new();
82	if (BN_hex2bn(&dhg->p, prime) < 0) {
83	BN_free(dhg->g);
84	BN_free(dhg->p);
85	goto fail;
86	}
87
88	return (1);
89	fail:
90	fprintf(stderr, "Bad prime description in line %d\n", linenum);
91	return (0);
92	}
93
94	DH *
95	choose_dh(int minbits)
96	{
97	FILE *f;
98	char line[1024];
99	int best, bestcount, which;
100	int linenum;
101	struct dhgroup dhg;
102
103	f = fopen(DH_PRIMES, "r");
104	if (!f) {
105	perror(DH_PRIMES);
106	log("WARNING: %s does not exist, using old prime", DH_PRIMES);
107	return (dh_new_group1());
108	}
109
110	linenum = 0;
111	best = bestcount = 0;
112	while (fgets(line, sizeof(line), f)) {
113	linenum++;
114	if (!parse_prime(linenum, line, &dhg))
115	continue;
116	BN_free(dhg.g);
117	BN_free(dhg.p);
118
119	if ((dhg.size > minbits && dhg.size < best) \|\|
120	(dhg.size > best && best < minbits)) {
121	best = dhg.size;
122	bestcount = 0;
123	}
124	if (dhg.size == best)
125	bestcount++;
126	}
127	fclose (f);
128
129	if (bestcount == 0) {
130	log("WARNING: no primes in %s, using old prime", DH_PRIMES);
131	return (dh_new_group1());
132	}
133
134	f = fopen(DH_PRIMES, "r");
135	if (!f) {
136	perror(DH_PRIMES);
137	exit(1);
138	}
139
140	linenum = 0;
141	which = arc4random() % bestcount;
142	while (fgets(line, sizeof(line), f)) {
143	if (!parse_prime(linenum, line, &dhg))
144	continue;
145	if (dhg.size != best)
146	continue;
147	if (linenum++ != which) {
148	BN_free(dhg.g);
149	BN_free(dhg.p);
150	continue;
151	}
152	break;
153	}
154	fclose(f);
155
156	return (dh_new_group(dhg.g, dhg.p));
157	}