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Add cyclic group abstraction, with test code. Separate off exponentation
[u/mdw/catacomb] / mpmont-mexp.c
CommitLineData
4cc02d06 1/* -*-c-*-
2 *
34e4f738 3 * $Id: mpmont-mexp.c,v 1.8 2004/04/01 12:50:09 mdw Exp $
4cc02d06 4 *
d34decd2 5 * Multiple simultaneous exponentiations
4cc02d06 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: mpmont-mexp.c,v $
34e4f738 33 * Revision 1.8 2004/04/01 12:50:09 mdw
34 * Add cyclic group abstraction, with test code. Separate off exponentation
35 * functions for better static linking. Fix a buttload of bugs on the way.
36 * Generally ensure that negative exponents do inversion correctly. Add
37 * table of standard prime-field subgroups. (Binary field subgroups are
38 * currently unimplemented but easy to add if anyone ever finds a good one.)
39 *
3beded37 40 * Revision 1.7 2002/01/13 13:49:14 mdw
41 * Make @const@-correct.
42 *
4640a0dd 43 * Revision 1.6 2001/06/16 13:00:20 mdw
44 * Use the generic exponentiation functions.
45 *
22bab86c 46 * Revision 1.5 2000/10/08 12:11:22 mdw
47 * Use @MP_EQ@ instead of @MP_CMP@.
48 *
d34decd2 49 * Revision 1.4 2000/06/17 11:45:09 mdw
50 * Major memory management overhaul. Added arena support. Use the secure
51 * arena for secret integers. Replace and improve the MP management macros
52 * (e.g., replace MP_MODIFY by MP_DEST).
53 *
ef5f4810 54 * Revision 1.3 1999/12/10 23:18:39 mdw
55 * Change interface for suggested destinations.
56 *
79a34029 57 * Revision 1.2 1999/11/21 11:35:10 mdw
58 * Performance improvement: use @mp_sqr@ and @mpmont_reduce@ instead of
59 * @mpmont_mul@ for squaring in exponentiation.
60 *
4cc02d06 61 * Revision 1.1 1999/11/19 13:19:29 mdw
62 * Simultaneous exponentiation support.
63 *
64 */
65
66/*----- Header files ------------------------------------------------------*/
67
68#include "mp.h"
69#include "mpmont.h"
70
4640a0dd 71#define EXP_WINSZ 3
72#include "mpmont-exp.h"
73
4cc02d06 74/*----- Main code ---------------------------------------------------------*/
75
76/* --- @mpmont_mexpr@ --- *
77 *
78 * Arguments: @mpmont *mm@ = pointer to Montgomery reduction context
ef5f4810 79 * @mp *d@ = fake destination
34e4f738 80 * @const mp_expfactor *f@ = pointer to array of factors
4cc02d06 81 * @size_t n@ = number of factors supplied
82 *
83 * Returns: If the bases are %$g_0, g_1, \ldots, g_{n-1}$% and the
84 * exponents are %$e_0, e_1, \ldots, e_{n-1}$% then the result
85 * is:
86 *
4640a0dd 87 * %$g_0^{e_0} g_1^{e_1} \ldots g_{n-1}^{e_{n-1}} \bmod m$%
88 *
89 * except that the %$g_i$% and result are in Montgomery form.
4cc02d06 90 */
91
34e4f738 92static mp *mexpr(mpmont *mm, mp *d, mp_expfactor *f, size_t n)
4cc02d06 93{
34e4f738 94 mp *a = MP_COPY(mm->r);
95 mp *spare = MP_NEW;
96 mp *g = MP_NEW;
4640a0dd 97 size_t i;
98
4640a0dd 99 for (i = 0; i < n; i++) {
34e4f738 100 mp *t;
101 if (f[i].exp->f & MP_BURN)
4640a0dd 102 spare = MP_NEWSEC;
34e4f738 103 if (f[i].exp->f & MP_NEG) {
104 t = mpmont_reduce(mm, f[i].base, f[i].base);
105 mp_gcd(&g, 0, &t, mm->m, t);
106 assert(MP_EQ(g, MP_ONE));
107 f[i].base = mpmont_mul(mm, t, t, mm->r2);
4cc02d06 108 }
109 }
34e4f738 110 mp_drop(g);
4640a0dd 111 EXP_SIMUL(a, f, n);
112 mp_drop(d);
113 mp_drop(spare);
34e4f738 114 for (i = 0; i < n; i++)
115 MP_DROP(f[i].base);
116 xfree(f);
4cc02d06 117 return (a);
118}
119
34e4f738 120mp *mpmont_mexpr(mpmont *mm, mp *d, const mp_expfactor *f, size_t n)
121{
122 mp_expfactor *ff = xmalloc(n * sizeof(mp_expfactor));
123 size_t i;
124
125 for (i = 0; i < n; i++) {
126 ff[i].base = MP_COPY(f[i].base);
127 ff[i].exp = f[i].exp;
128 }
129 return (mexpr(mm, d, ff, n));
130}
131
4cc02d06 132/* --- @mpmont_mexp@ --- *
133 *
134 * Arguments: @mpmont *mm@ = pointer to Montgomery reduction context
ef5f4810 135 * @mp *d@ = fake destination
3beded37 136 * @const mp_expfactor *f@ = pointer to array of factors
4cc02d06 137 * @size_t n@ = number of factors supplied
138 *
139 * Returns: Product of bases raised to exponents, all mod @m@.
140 *
141 * Use: Convenient interface over @mpmont_mexpr@.
142 */
143
3beded37 144mp *mpmont_mexp(mpmont *mm, mp *d, const mp_expfactor *f, size_t n)
4cc02d06 145{
34e4f738 146 mp_expfactor *ff = xmalloc(n * sizeof(mp_expfactor));
4640a0dd 147 size_t i;
148
149 for (i = 0; i < n; i++) {
34e4f738 150 ff[i].base = mpmont_mul(mm, MP_NEW, f[i].base, mm->r2);
151 ff[i].exp = f[i].exp;
4640a0dd 152 }
34e4f738 153 d = mexpr(mm, d, ff, n);
154 return (mpmont_reduce(mm, d, d));
4cc02d06 155}
156
157/*----- Test rig ----------------------------------------------------------*/
158
159#ifdef TEST_RIG
160
161#include <mLib/testrig.h>
162
163static int verify(size_t n, dstr *v)
164{
165 mp *m = *(mp **)v[0].buf;
4640a0dd 166 mp_expfactor *f = xmalloc(n * sizeof(*f));
4cc02d06 167 mp *r, *rr;
168 size_t i, j;
169 mpmont mm;
170 int ok = 1;
171
172 j = 1;
173 for (i = 0; i < n; i++) {
174 f[i].base = *(mp **)v[j++].buf;
175 f[i].exp = *(mp **)v[j++].buf;
176 }
177
178 rr = *(mp **)v[j].buf;
179 mpmont_create(&mm, m);
ef5f4810 180 r = mpmont_mexp(&mm, MP_NEW, f, n);
22bab86c 181 if (!MP_EQ(r, rr)) {
4cc02d06 182 fputs("\n*** mexp failed\n", stderr);
183 fputs("m = ", stderr); mp_writefile(m, stderr, 10);
184 for (i = 0; i < n; i++) {
185 fprintf(stderr, "\ng_%u = ", i);
186 mp_writefile(f[i].base, stderr, 10);
187 fprintf(stderr, "\ne_%u = ", i);
188 mp_writefile(f[i].exp, stderr, 10);
189 }
190 fputs("\nr = ", stderr); mp_writefile(r, stderr, 10);
191 fputs("\nR = ", stderr); mp_writefile(rr, stderr, 10);
192 fputc('\n', stderr);
193 ok = 0;
194 }
195
196 for (i = 0; i < n; i++) {
197 MP_DROP(f[i].base);
198 MP_DROP(f[i].exp);
199 }
200 MP_DROP(m);
201 MP_DROP(r);
202 MP_DROP(rr);
203 mpmont_destroy(&mm);
ef5f4810 204 assert(mparena_count(MPARENA_GLOBAL) == 0);
4cc02d06 205 return (ok);
206}
207
208static int t1(dstr *v) { return verify(1, v); }
209static int t2(dstr *v) { return verify(2, v); }
210static int t3(dstr *v) { return verify(3, v); }
211static int t4(dstr *v) { return verify(4, v); }
212static int t5(dstr *v) { return verify(5, v); }
213
214static test_chunk tests[] = {
215 { "mexp-1", t1, { &type_mp,
216 &type_mp, &type_mp,
217 &type_mp, 0 } },
218 { "mexp-2", t2, { &type_mp,
219 &type_mp, &type_mp,
220 &type_mp, &type_mp,
221 &type_mp, 0 } },
222 { "mexp-3", t3, { &type_mp,
223 &type_mp, &type_mp,
224 &type_mp, &type_mp,
225 &type_mp, &type_mp,
226 &type_mp, 0 } },
227 { "mexp-4", t4, { &type_mp,
228 &type_mp, &type_mp,
229 &type_mp, &type_mp,
230 &type_mp, &type_mp,
231 &type_mp, &type_mp,
232 &type_mp, 0 } },
233 { "mexp-5", t5, { &type_mp,
234 &type_mp, &type_mp,
235 &type_mp, &type_mp,
236 &type_mp, &type_mp,
237 &type_mp, &type_mp,
238 &type_mp, &type_mp,
239 &type_mp, 0 } },
240 { 0, 0, { 0 } }
241};
242
243int main(int argc, char *argv[])
244{
245 sub_init();
246 test_run(argc, argv, tests, SRCDIR "/tests/mpmont");
247 return (0);
248}
249
250#endif
251
252/*----- That's all, folks -------------------------------------------------*/
Catacomb cryptographic library (downstream of http://git.distorted.org.uk/~mdw/catacomb/)