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1 | /* -*-c-*- |
2 | * |
3 | * $Id: dsa-sign.c,v 1.1 1999/11/19 19:28:00 mdw Exp $ |
4 | * |
5 | * DSA signing operation |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Catacomb. |
13 | * |
14 | * Catacomb is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * Catacomb is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with Catacomb; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: dsa-sign.c,v $ |
33 | * Revision 1.1 1999/11/19 19:28:00 mdw |
34 | * Implementation of the Digital Signature Algorithm. |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include "dsa.h" |
41 | #include "mp.h" |
42 | #include "mpmont.h" |
43 | |
44 | /*----- Main code ---------------------------------------------------------*/ |
45 | |
46 | /* --- @dsa_mksig@ --- * |
47 | * |
48 | * Arguments: @const dsa_param *dp@ = pointer to DSA parameters |
49 | * @const mp *a@ = secret signing key |
50 | * @const mp *m@ = message to be signed |
51 | * @const mp *k@ = random data |
52 | * @mp **rr, **ss@ = where to put output parameters |
53 | * |
54 | * Returns: --- |
55 | * |
56 | * Use: Computes a DSA signature of a message. |
57 | */ |
58 | |
59 | void dsa_mksig(const dsa_param *dp, const mp *a, const mp *m, const mp *k, |
60 | mp **rr, mp **ss) |
61 | { |
62 | mpmont pm, qm; |
63 | mp *k1, *r; |
64 | mp *rrr, *ar; |
65 | |
66 | /* --- Create the Montgomery contexts --- */ |
67 | |
68 | mpmont_create(&pm, dp->p); |
69 | mpmont_create(&qm, dp->q); |
70 | |
71 | /* --- Compute %$r = (g^k \bmod p) \bmod q$% --- */ |
72 | |
73 | r = mpmont_exp(&pm, dp->g, k); |
74 | mp_div(0, &r, r, dp->q); |
75 | *rr = r; |
76 | |
77 | /* --- Compute %$k^{-1} \bmod q$% --- */ |
78 | |
79 | mp_gcd(0, 0, &k1, dp->q, (mp *)k); |
80 | |
81 | /* --- Now for %$k^{-1}(m + ar)$% --- */ |
82 | |
83 | rrr = mpmont_mul(&qm, MP_NEW, r, qm.r2); |
84 | ar = mpmont_mul(&qm, MP_NEW, a, rrr); |
85 | ar = mp_add(ar, ar, m); |
86 | if (MP_CMP(ar, >=, dp->q)) |
87 | ar = mp_sub(ar, ar, dp->q); |
88 | rrr = mpmont_mul(&qm, rrr, ar, qm.r2); |
89 | ar = mpmont_mul(&qm, ar, rrr, k1); |
90 | *ss = ar; |
91 | |
92 | /* --- Tidy things up a little --- */ |
93 | |
94 | mp_drop(rrr); |
95 | mp_drop(k1); |
96 | mpmont_destroy(&pm); |
97 | mpmont_destroy(&qm); |
98 | } |
99 | |
100 | /* --- @dsa_sign@ --- * |
101 | * |
102 | * Arguments: @dsa_param *dp@ = pointer to DSA parameters |
103 | * @mp *a@ = pointer to secret signing key |
104 | * @const void *m@ = pointer to message |
105 | * @size_t msz@ = size of the message |
106 | * @const void *k@ = secret random data for securing signature |
107 | * @size_t ksz@ = size of secret data |
108 | * @void *r@ = pointer to output space for @r@ |
109 | * @size_t rsz@ = size of output space for @r@ |
110 | * @void *s@ = pointer to output space for @s@ |
111 | * @size_t ssz@ = size of output space for @s@ |
112 | * |
113 | * Returns: --- |
114 | * |
115 | * Use: Signs a message, storing the results in a big-endian binary |
116 | * form. |
117 | */ |
118 | |
119 | void dsa_sign(dsa_param *dp, mp *a, |
120 | const void *m, size_t msz, const void *k, size_t ksz, |
121 | void *r, size_t rsz, void *s, size_t ssz) |
122 | { |
123 | mp *mm = mp_loadb(MP_NEW, m, msz); |
124 | mp *km = mp_loadb(MP_NEW, k, ksz); |
125 | mp *rm, *sm; |
126 | dsa_mksig(dp, a, mm, km, &rm, &sm); |
127 | mp_storeb(rm, r, rsz); |
128 | mp_storeb(sm, s, ssz); |
129 | mp_drop(mm); mp_drop(km); |
130 | mp_drop(rm); mp_drop(sm); |
131 | } |
132 | |
133 | /*----- Test rig ----------------------------------------------------------*/ |
134 | |
135 | #ifdef TEST_RIG |
136 | |
137 | #include <mLib/testrig.h> |
138 | |
139 | #include "sha.h" |
140 | |
141 | static int verify(dstr *v) |
142 | { |
143 | dsa_param dp; |
144 | mp *x; |
145 | sha_ctx c; |
146 | octet hash[SHA_HASHSZ]; |
147 | dsa_sig s; |
148 | int ok = 1; |
149 | |
150 | dp.q = *(mp **)v[0].buf; |
151 | dp.p = *(mp **)v[1].buf; |
152 | dp.g = *(mp **)v[2].buf; |
153 | x = *(mp **)v[3].buf; |
154 | |
155 | sha_init(&c); |
156 | sha_hash(&c, v[4].buf, v[4].len); |
157 | sha_done(&c, hash); |
158 | |
159 | dsa_sign(&dp, x, hash, sizeof(hash), v[5].buf, v[5].len, |
160 | s.r, sizeof(s.r), s.s, sizeof(s.s)); |
161 | |
162 | if (v[6].len != sizeof(s.r) || v[7].len != sizeof(s.s) || |
163 | memcmp(s.r, v[6].buf, sizeof(s.r)) != 0 || |
164 | memcmp(s.s, v[7].buf, sizeof(s.s)) != 0) { |
165 | fputs("\n*** signature failed", stderr); |
166 | fputs("\nq = ", stderr); mp_writefile(dp.q, stderr, 16); |
167 | fputs("\np = ", stderr); mp_writefile(dp.p, stderr, 16); |
168 | fputs("\ng = ", stderr); mp_writefile(dp.g, stderr, 16); |
169 | fputs("\nx = ", stderr); mp_writefile(x, stderr, 16); |
170 | fprintf(stderr, "\nmessage = `%s'", v[4].buf); |
171 | fputs("\nk = ", stderr); type_hex.dump(&v[5], stderr); |
172 | fputs("\nR = ", stderr); type_hex.dump(&v[6], stderr); |
173 | fputs("\nS = ", stderr); type_hex.dump(&v[7], stderr); |
174 | |
175 | { |
176 | mp *m = MP_NEW; |
177 | m = mp_loadb(m, hash, sizeof(hash)); |
178 | fputs("\nm = ", stderr); mp_writefile(m, stderr, 16); |
179 | m = mp_loadb(m, s.r, sizeof(s.r)); |
180 | fputs("\nr = ", stderr); mp_writefile(m, stderr, 16); |
181 | m = mp_loadb(m, s.s, sizeof(s.s)); |
182 | fputs("\ns = ", stderr); mp_writefile(m, stderr, 16); |
183 | mp_drop(m); |
184 | } |
185 | |
186 | fputc('\n', stderr); |
187 | ok = 0; |
188 | } |
189 | |
190 | mp_drop(dp.p); |
191 | mp_drop(dp.q); |
192 | mp_drop(dp.g); |
193 | mp_drop(x); |
194 | return (ok); |
195 | } |
196 | |
197 | static test_chunk tests[] = { |
198 | { "sign", verify, |
199 | { &type_mp, &type_mp, &type_mp, &type_mp, |
200 | &type_string, &type_hex, &type_hex, &type_hex, 0 } }, |
201 | { 0, 0, { 0 } } |
202 | }; |
203 | |
204 | int main(int argc, char *argv[]) |
205 | { |
206 | sub_init(); |
207 | test_run(argc, argv, tests, SRCDIR "/tests/dsa"); |
208 | return (0); |
209 | } |
210 | |
211 | #endif |
212 | |
213 | /*----- That's all, folks -------------------------------------------------*/ |