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Diffstat (limited to 'dh.c')
-rw-r--r-- | dh.c | 157 |
1 files changed, 157 insertions, 0 deletions
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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 | } | ||