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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: dsa-sign.c,v 1.3 2004/04/08 01:36:15 mdw Exp $ |
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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 | |
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30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include "dsa.h" |
33 | #include "mp.h" |
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34 | #include "mpbarrett.h" |
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35 | #include "mpmont.h" |
36 | |
37 | /*----- Main code ---------------------------------------------------------*/ |
38 | |
39 | /* --- @dsa_mksig@ --- * |
40 | * |
41 | * Arguments: @const dsa_param *dp@ = pointer to DSA parameters |
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42 | * @mp *a@ = secret signing key |
43 | * @mp *m@ = message to be signed |
44 | * @mp *k@ = random data |
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45 | * @mp **rr, **ss@ = where to put output parameters |
46 | * |
47 | * Returns: --- |
48 | * |
49 | * Use: Computes a DSA signature of a message. |
50 | */ |
51 | |
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52 | void dsa_mksig(const dsa_param *dp, mp *a, mp *m, mp *k, mp **rr, mp **ss) |
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53 | { |
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54 | mpmont pm; |
55 | mpbarrett qb; |
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56 | mp *k1, *r; |
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57 | mp *ar; |
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58 | |
59 | /* --- Compute %$r = (g^k \bmod p) \bmod q$% --- */ |
60 | |
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61 | mpmont_create(&pm, dp->p); |
62 | r = mpmont_exp(&pm, MP_NEW, dp->g, k); |
63 | mpmont_destroy(&pm); |
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64 | mp_div(0, &r, r, dp->q); |
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65 | |
66 | /* --- Compute %$k^{-1} \bmod q$% --- */ |
67 | |
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68 | k1 = mp_modinv(MP_NEW, k, dp->q); |
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69 | |
70 | /* --- Now for %$k^{-1}(m + ar)$% --- */ |
71 | |
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72 | mpbarrett_create(&qb, dp->q); |
73 | ar = mp_mul(MP_NEW, a, r); |
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74 | ar = mp_add(ar, ar, m); |
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75 | ar = mpbarrett_reduce(&qb, ar, ar); |
76 | ar = mp_mul(ar, ar, k1); |
77 | ar = mpbarrett_reduce(&qb, ar, ar); |
78 | mpbarrett_destroy(&qb); |
79 | MP_DROP(k1); |
80 | if (*rr) MP_DROP(*rr); |
81 | if (*ss) MP_DROP(*ss); |
82 | *rr = r; |
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83 | *ss = ar; |
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84 | } |
85 | |
86 | /* --- @dsa_sign@ --- * |
87 | * |
88 | * Arguments: @dsa_param *dp@ = pointer to DSA parameters |
89 | * @mp *a@ = pointer to secret signing key |
90 | * @const void *m@ = pointer to message |
91 | * @size_t msz@ = size of the message |
92 | * @const void *k@ = secret random data for securing signature |
93 | * @size_t ksz@ = size of secret data |
94 | * @void *r@ = pointer to output space for @r@ |
95 | * @size_t rsz@ = size of output space for @r@ |
96 | * @void *s@ = pointer to output space for @s@ |
97 | * @size_t ssz@ = size of output space for @s@ |
98 | * |
99 | * Returns: --- |
100 | * |
101 | * Use: Signs a message, storing the results in a big-endian binary |
102 | * form. |
103 | */ |
104 | |
105 | void dsa_sign(dsa_param *dp, mp *a, |
106 | const void *m, size_t msz, const void *k, size_t ksz, |
107 | void *r, size_t rsz, void *s, size_t ssz) |
108 | { |
109 | mp *mm = mp_loadb(MP_NEW, m, msz); |
110 | mp *km = mp_loadb(MP_NEW, k, ksz); |
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111 | mp *rm = MP_NEW, *sm = MP_NEW; |
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112 | dsa_mksig(dp, a, mm, km, &rm, &sm); |
113 | mp_storeb(rm, r, rsz); |
114 | mp_storeb(sm, s, ssz); |
115 | mp_drop(mm); mp_drop(km); |
116 | mp_drop(rm); mp_drop(sm); |
117 | } |
118 | |
119 | /*----- Test rig ----------------------------------------------------------*/ |
120 | |
121 | #ifdef TEST_RIG |
122 | |
123 | #include <mLib/testrig.h> |
124 | |
125 | #include "sha.h" |
126 | |
127 | static int verify(dstr *v) |
128 | { |
129 | dsa_param dp; |
130 | mp *x; |
131 | sha_ctx c; |
132 | octet hash[SHA_HASHSZ]; |
133 | dsa_sig s; |
134 | int ok = 1; |
135 | |
136 | dp.q = *(mp **)v[0].buf; |
137 | dp.p = *(mp **)v[1].buf; |
138 | dp.g = *(mp **)v[2].buf; |
139 | x = *(mp **)v[3].buf; |
140 | |
141 | sha_init(&c); |
142 | sha_hash(&c, v[4].buf, v[4].len); |
143 | sha_done(&c, hash); |
144 | |
145 | dsa_sign(&dp, x, hash, sizeof(hash), v[5].buf, v[5].len, |
146 | s.r, sizeof(s.r), s.s, sizeof(s.s)); |
147 | |
148 | if (v[6].len != sizeof(s.r) || v[7].len != sizeof(s.s) || |
149 | memcmp(s.r, v[6].buf, sizeof(s.r)) != 0 || |
150 | memcmp(s.s, v[7].buf, sizeof(s.s)) != 0) { |
151 | fputs("\n*** signature failed", stderr); |
152 | fputs("\nq = ", stderr); mp_writefile(dp.q, stderr, 16); |
153 | fputs("\np = ", stderr); mp_writefile(dp.p, stderr, 16); |
154 | fputs("\ng = ", stderr); mp_writefile(dp.g, stderr, 16); |
155 | fputs("\nx = ", stderr); mp_writefile(x, stderr, 16); |
156 | fprintf(stderr, "\nmessage = `%s'", v[4].buf); |
157 | fputs("\nk = ", stderr); type_hex.dump(&v[5], stderr); |
158 | fputs("\nR = ", stderr); type_hex.dump(&v[6], stderr); |
159 | fputs("\nS = ", stderr); type_hex.dump(&v[7], stderr); |
160 | |
161 | { |
162 | mp *m = MP_NEW; |
163 | m = mp_loadb(m, hash, sizeof(hash)); |
164 | fputs("\nm = ", stderr); mp_writefile(m, stderr, 16); |
165 | m = mp_loadb(m, s.r, sizeof(s.r)); |
166 | fputs("\nr = ", stderr); mp_writefile(m, stderr, 16); |
167 | m = mp_loadb(m, s.s, sizeof(s.s)); |
168 | fputs("\ns = ", stderr); mp_writefile(m, stderr, 16); |
169 | mp_drop(m); |
170 | } |
171 | |
172 | fputc('\n', stderr); |
173 | ok = 0; |
174 | } |
175 | |
176 | mp_drop(dp.p); |
177 | mp_drop(dp.q); |
178 | mp_drop(dp.g); |
179 | mp_drop(x); |
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180 | assert(mparena_count(MPARENA_GLOBAL) == 0); |
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181 | return (ok); |
182 | } |
183 | |
184 | static test_chunk tests[] = { |
185 | { "sign", verify, |
186 | { &type_mp, &type_mp, &type_mp, &type_mp, |
187 | &type_string, &type_hex, &type_hex, &type_hex, 0 } }, |
188 | { 0, 0, { 0 } } |
189 | }; |
190 | |
191 | int main(int argc, char *argv[]) |
192 | { |
193 | sub_init(); |
194 | test_run(argc, argv, tests, SRCDIR "/tests/dsa"); |
195 | return (0); |
196 | } |
197 | |
198 | #endif |
199 | |
200 | /*----- That's all, folks -------------------------------------------------*/ |