3 * $Id: dsa-sign.c,v 1.2 1999/12/10 23:18:38 mdw Exp $
5 * DSA signing operation
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
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.
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.
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,
30 /*----- Revision history --------------------------------------------------*
32 * $Log: dsa-sign.c,v $
33 * Revision 1.2 1999/12/10 23:18:38 mdw
34 * Change interface for suggested destinations.
36 * Revision 1.1 1999/11/19 19:28:00 mdw
37 * Implementation of the Digital Signature Algorithm.
41 /*----- Header files ------------------------------------------------------*/
45 #include "mpbarrett.h"
48 /*----- Main code ---------------------------------------------------------*/
50 /* --- @dsa_mksig@ --- *
52 * Arguments: @const dsa_param *dp@ = pointer to DSA parameters
53 * @mp *a@ = secret signing key
54 * @mp *m@ = message to be signed
55 * @mp *k@ = random data
56 * @mp **rr, **ss@ = where to put output parameters
60 * Use: Computes a DSA signature of a message.
63 void dsa_mksig(const dsa_param *dp, mp *a, mp *m, mp *k, mp **rr, mp **ss)
70 /* --- Compute %$r = (g^k \bmod p) \bmod q$% --- */
72 mpmont_create(&pm, dp->p);
73 r = mpmont_exp(&pm, MP_NEW, dp->g, k);
75 mp_div(0, &r, r, dp->q);
77 /* --- Compute %$k^{-1} \bmod q$% --- */
79 mp_gcd(0, 0, &k1, dp->q, k);
81 /* --- Now for %$k^{-1}(m + ar)$% --- */
83 mpbarrett_create(&qb, dp->q);
84 ar = mp_mul(MP_NEW, a, r);
85 ar = mp_add(ar, ar, m);
86 ar = mpbarrett_reduce(&qb, ar, ar);
87 ar = mp_mul(ar, ar, k1);
88 ar = mpbarrett_reduce(&qb, ar, ar);
89 mpbarrett_destroy(&qb);
91 if (*rr) MP_DROP(*rr);
92 if (*ss) MP_DROP(*ss);
97 /* --- @dsa_sign@ --- *
99 * Arguments: @dsa_param *dp@ = pointer to DSA parameters
100 * @mp *a@ = pointer to secret signing key
101 * @const void *m@ = pointer to message
102 * @size_t msz@ = size of the message
103 * @const void *k@ = secret random data for securing signature
104 * @size_t ksz@ = size of secret data
105 * @void *r@ = pointer to output space for @r@
106 * @size_t rsz@ = size of output space for @r@
107 * @void *s@ = pointer to output space for @s@
108 * @size_t ssz@ = size of output space for @s@
112 * Use: Signs a message, storing the results in a big-endian binary
116 void dsa_sign(dsa_param *dp, mp *a,
117 const void *m, size_t msz, const void *k, size_t ksz,
118 void *r, size_t rsz, void *s, size_t ssz)
120 mp *mm = mp_loadb(MP_NEW, m, msz);
121 mp *km = mp_loadb(MP_NEW, k, ksz);
122 mp *rm = MP_NEW, *sm = MP_NEW;
123 dsa_mksig(dp, a, mm, km, &rm, &sm);
124 mp_storeb(rm, r, rsz);
125 mp_storeb(sm, s, ssz);
126 mp_drop(mm); mp_drop(km);
127 mp_drop(rm); mp_drop(sm);
130 /*----- Test rig ----------------------------------------------------------*/
134 #include <mLib/testrig.h>
138 static int verify(dstr *v)
143 octet hash[SHA_HASHSZ];
147 dp.q = *(mp **)v[0].buf;
148 dp.p = *(mp **)v[1].buf;
149 dp.g = *(mp **)v[2].buf;
150 x = *(mp **)v[3].buf;
153 sha_hash(&c, v[4].buf, v[4].len);
156 dsa_sign(&dp, x, hash, sizeof(hash), v[5].buf, v[5].len,
157 s.r, sizeof(s.r), s.s, sizeof(s.s));
159 if (v[6].len != sizeof(s.r) || v[7].len != sizeof(s.s) ||
160 memcmp(s.r, v[6].buf, sizeof(s.r)) != 0 ||
161 memcmp(s.s, v[7].buf, sizeof(s.s)) != 0) {
162 fputs("\n*** signature failed", stderr);
163 fputs("\nq = ", stderr); mp_writefile(dp.q, stderr, 16);
164 fputs("\np = ", stderr); mp_writefile(dp.p, stderr, 16);
165 fputs("\ng = ", stderr); mp_writefile(dp.g, stderr, 16);
166 fputs("\nx = ", stderr); mp_writefile(x, stderr, 16);
167 fprintf(stderr, "\nmessage = `%s'", v[4].buf);
168 fputs("\nk = ", stderr); type_hex.dump(&v[5], stderr);
169 fputs("\nR = ", stderr); type_hex.dump(&v[6], stderr);
170 fputs("\nS = ", stderr); type_hex.dump(&v[7], stderr);
174 m = mp_loadb(m, hash, sizeof(hash));
175 fputs("\nm = ", stderr); mp_writefile(m, stderr, 16);
176 m = mp_loadb(m, s.r, sizeof(s.r));
177 fputs("\nr = ", stderr); mp_writefile(m, stderr, 16);
178 m = mp_loadb(m, s.s, sizeof(s.s));
179 fputs("\ns = ", stderr); mp_writefile(m, stderr, 16);
191 assert(mparena_count(MPARENA_GLOBAL) == 0);
195 static test_chunk tests[] = {
197 { &type_mp, &type_mp, &type_mp, &type_mp,
198 &type_string, &type_hex, &type_hex, &type_hex, 0 } },
202 int main(int argc, char *argv[])
205 test_run(argc, argv, tests, SRCDIR "/tests/dsa");
211 /*----- That's all, folks -------------------------------------------------*/