blob: 35e9014333b899c17a98eba015fc8cd673ad434e [file] [log] [blame]
Damien Miller874d77b2000-10-14 16:23:11 +11001/*
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"
Ben Lindstrom14920292000-11-21 21:24:55 +000026RCSID("$OpenBSD: dh.c,v 1.3 2000/11/16 17:55:43 markus Exp $");
Damien Miller874d77b2000-10-14 16:23:11 +110027
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
39int
40parse_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
94DH *
95choose_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) {
Damien Miller874d77b2000-10-14 16:23:11 +1100105 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) {
Ben Lindstrom14920292000-11-21 21:24:55 +0000135 fatal("WARNING: %s dissappeared, giving up", DH_PRIMES);
Damien Miller874d77b2000-10-14 16:23:11 +1100136 }
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}