[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 1.4 2001/01/15 21:43:51 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:
	error("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) {
		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) {
		fatal("WARNING: %s dissappeared, giving up", DH_PRIMES);
	}

	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"
b5c334cc	26	RCSID("$OpenBSD: dh.c,v 1.4 2001/01/15 21:43:51 markus Exp $");
94ec8c6b	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:
b5c334cc	90	error("Bad prime description in line %d\n", linenum);
94ec8c6b	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) {
94ec8c6b	105	log("WARNING: %s does not exist, using old prime", DH_PRIMES);
	106	return (dh_new_group1());
	107	}
	108
	109	linenum = 0;
	110	best = bestcount = 0;
	111	while (fgets(line, sizeof(line), f)) {
	112	linenum++;
	113	if (!parse_prime(linenum, line, &dhg))
	114	continue;
	115	BN_free(dhg.g);
	116	BN_free(dhg.p);
	117
	118	if ((dhg.size > minbits && dhg.size < best) \|\|
	119	(dhg.size > best && best < minbits)) {
	120	best = dhg.size;
	121	bestcount = 0;
	122	}
	123	if (dhg.size == best)
	124	bestcount++;
	125	}
	126	fclose (f);
	127
	128	if (bestcount == 0) {
	129	log("WARNING: no primes in %s, using old prime", DH_PRIMES);
	130	return (dh_new_group1());
	131	}
	132
	133	f = fopen(DH_PRIMES, "r");
	134	if (!f) {
d343d900	135	fatal("WARNING: %s dissappeared, giving up", DH_PRIMES);
94ec8c6b	136	}
	137
	138	linenum = 0;
	139	which = arc4random() % bestcount;
	140	while (fgets(line, sizeof(line), f)) {
	141	if (!parse_prime(linenum, line, &dhg))
	142	continue;
	143	if (dhg.size != best)
	144	continue;
	145	if (linenum++ != which) {
	146	BN_free(dhg.g);
	147	BN_free(dhg.p);
	148	continue;
	149	}
	150	break;
	151	}
	152	fclose(f);
	153
	154	return (dh_new_group(dhg.g, dhg.p));
	155	}