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comparison gendss.c @ 285:1b9e69c058d2

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propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3) to branch 'au.asn.ucc.matt.dropbear' (head fdf4a7a3b97ae5046139915de7e40399cceb2c01)
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:23:58 +0000
parents c9483550701b
children 740e782679be b50f0107e505 76097ec1a29a
comparison
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281:997e6f7dc01e 285:1b9e69c058d2
1 /*
2 * Dropbear - a SSH2 server
3 *
4 * Copyright (c) 2002,2003 Matt Johnston
5 * All rights reserved.
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23 * SOFTWARE. */
24
25 #include "includes.h"
26 #include "dbutil.h"
27 #include "signkey.h"
28 #include "bignum.h"
29 #include "random.h"
30 #include "buffer.h"
31 #include "gendss.h"
32 #include "dss.h"
33
34 #define QSIZE 20 /* 160 bit */
35
36 /* This is just a test */
37
38 #ifdef DROPBEAR_DSS
39
40 static void getq(dss_key *key);
41 static void getp(dss_key *key, unsigned int size);
42 static void getg(dss_key *key);
43 static void getx(dss_key *key);
44 static void gety(dss_key *key);
45
46 dss_key * gen_dss_priv_key(unsigned int size) {
47
48 dss_key *key;
49
50 key = (dss_key*)m_malloc(sizeof(dss_key));
51
52 key->p = (mp_int*)m_malloc(sizeof(mp_int));
53 key->q = (mp_int*)m_malloc(sizeof(mp_int));
54 key->g = (mp_int*)m_malloc(sizeof(mp_int));
55 key->y = (mp_int*)m_malloc(sizeof(mp_int));
56 key->x = (mp_int*)m_malloc(sizeof(mp_int));
57 m_mp_init_multi(key->p, key->q, key->g, key->y, key->x, NULL);
58
59 seedrandom();
60
61 getq(key);
62 getp(key, size);
63 getg(key);
64 getx(key);
65 gety(key);
66
67 return key;
68
69 }
70
71 static void getq(dss_key *key) {
72
73 char buf[QSIZE];
74
75 /* 160 bit prime */
76 genrandom(buf, QSIZE);
77 buf[0] |= 0x80; /* top bit high */
78 buf[QSIZE-1] |= 0x01; /* bottom bit high */
79
80 bytes_to_mp(key->q, buf, QSIZE);
81
82 /* 18 rounds are required according to HAC */
83 if (mp_prime_next_prime(key->q, 18, 0) != MP_OKAY) {
84 fprintf(stderr, "dss key generation failed\n");
85 exit(1);
86 }
87 }
88
89 static void getp(dss_key *key, unsigned int size) {
90
91 DEF_MP_INT(tempX);
92 DEF_MP_INT(tempC);
93 DEF_MP_INT(tempP);
94 DEF_MP_INT(temp2q);
95 int result;
96 unsigned char *buf;
97
98 m_mp_init_multi(&tempX, &tempC, &tempP, &temp2q, NULL);
99
100
101 /* 2*q */
102 if (mp_mul_d(key->q, 2, &temp2q) != MP_OKAY) {
103 fprintf(stderr, "dss key generation failed\n");
104 exit(1);
105 }
106
107 buf = (unsigned char*)m_malloc(size);
108
109 result = 0;
110 do {
111
112 genrandom(buf, size);
113 buf[0] |= 0x80; /* set the top bit high */
114
115 /* X is a random mp_int */
116 bytes_to_mp(&tempX, buf, size);
117
118 /* C = X mod 2q */
119 if (mp_mod(&tempX, &temp2q, &tempC) != MP_OKAY) {
120 fprintf(stderr, "dss key generation failed\n");
121 exit(1);
122 }
123
124 /* P = X - (C - 1) = X - C + 1*/
125 if (mp_sub(&tempX, &tempC, &tempP) != MP_OKAY) {
126 fprintf(stderr, "dss key generation failed\n");
127 exit(1);
128 }
129
130 if (mp_add_d(&tempP, 1, key->p) != MP_OKAY) {
131 fprintf(stderr, "dss key generation failed\n");
132 exit(1);
133 }
134
135 /* now check for prime, 5 rounds is enough according to HAC */
136 /* result == 1 => p is prime */
137 if (mp_prime_is_prime(key->p, 5, &result) != MP_OKAY) {
138 fprintf(stderr, "dss key generation failed\n");
139 exit(1);
140 }
141 } while (!result);
142
143 mp_clear_multi(&tempX, &tempC, &tempP, &temp2q, NULL);
144 m_burn(buf, size);
145 m_free(buf);
146 }
147
148 static void getg(dss_key * key) {
149
150 DEF_MP_INT(div);
151 DEF_MP_INT(h);
152 DEF_MP_INT(val);
153
154 m_mp_init_multi(&div, &h, &val, NULL);
155
156 /* get div=(p-1)/q */
157 if (mp_sub_d(key->p, 1, &val) != MP_OKAY) {
158 fprintf(stderr, "dss key generation failed\n");
159 exit(1);
160 }
161 if (mp_div(&val, key->q, &div, NULL) != MP_OKAY) {
162 fprintf(stderr, "dss key generation failed\n");
163 exit(1);
164 }
165
166 /* initialise h=1 */
167 mp_set(&h, 1);
168 do {
169 /* now keep going with g=h^div mod p, until g > 1 */
170 if (mp_exptmod(&h, &div, key->p, key->g) != MP_OKAY) {
171 fprintf(stderr, "dss key generation failed\n");
172 exit(1);
173 }
174
175 if (mp_add_d(&h, 1, &h) != MP_OKAY) {
176 fprintf(stderr, "dss key generation failed\n");
177 exit(1);
178 }
179
180 } while (mp_cmp_d(key->g, 1) != MP_GT);
181
182 mp_clear_multi(&div, &h, &val, NULL);
183 }
184
185 static void getx(dss_key *key) {
186
187 gen_random_mpint(key->q, key->x);
188 }
189
190 static void gety(dss_key *key) {
191
192 if (mp_exptmod(key->g, key->x, key->p, key->y) != MP_OKAY) {
193 fprintf(stderr, "dss key generation failed\n");
194 exit(1);
195 }
196 }
197
198 #endif /* DROPBEAR_DSS */