git.distorted.org.uk Git - u/mdw/catacomb/blob - mpbarrett-mexp.c

   1 /* -*-c-*-
   2  *
   3  * $Id$
   4  *
   5  * Multiple simultaneous exponentiations
   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 /*----- Header files ------------------------------------------------------*/
  31
  32 #include "mp.h"
  33 #include "mpbarrett.h"
  34
  35 #define EXP_WINSZ 3
  36 #include "mpbarrett-exp.h"
  37
  38 /*----- Main code ---------------------------------------------------------*/
  39
  40 /* --- @mpbarrett_mexp@ --- *
  41  *
  42  * Arguments:   @mpbarrett *mb@ = pointer to Barrett reduction context
  43  *              @mp *d@ = fake destination
  44  *              @const mp_expfactor *f@ = pointer to array of factors
  45  *              @size_t n@ = number of factors supplied
  46  *
  47  * Returns:     If the bases are %$g_0, g_1, \ldots, g_{n-1}$% and the
  48  *              exponents are %$e_0, e_1, \ldots, e_{n-1}$% then the result
  49  *              is:
  50  *
  51  *              %$g_0^{e_0} g_1^{e_1} \ldots g_{n-1}^{e_{n-1}} \bmod m$%
  52  */
  53
  54 mp *mpbarrett_mexp(mpbarrett *mb, mp *d, const mp_expfactor *f, size_t n)
  55 {
  56   mp_expfactor *ff = xmalloc(n * sizeof(mp_expfactor));
  57   mp *a = MP_ONE;
  58   mp *spare;
  59   mp *g = MP_NEW;
  60   size_t i;
  61
  62   spare = MP_NEW;
  63   for (i = 0; i < n; i++) {
  64     if (f[i].exp->f & MP_BURN)
  65       spare = MP_NEWSEC;
  66     if (MP_NEGP(f[i].exp))
  67       ff[i].base = mp_modinv(MP_NEW, f[i].base, mb->m);
  68     else
  69       ff[i].base = MP_COPY(f[i].base);
  70     ff[i].exp = f[i].exp;
  71   }
  72   mp_drop(g);
  73   EXP_SIMUL(a, ff, n);
  74   mp_drop(d);
  75   mp_drop(spare);
  76   for (i = 0; i < n; i++)
  77     mp_drop(ff[i].base);
  78   xfree(ff);
  79   return (a);
  80 }
  81
  82 /*----- Test rig ----------------------------------------------------------*/
  83
  84 #ifdef TEST_RIG
  85
  86 #include <mLib/testrig.h>
  87
  88 static int verify(size_t n, dstr *v)
  89 {
  90   mp *m = *(mp **)v[0].buf;
  91   mp_expfactor *f = xmalloc(n * sizeof(*f));
  92   mp *r, *rr;
  93   size_t i, j;
  94   mpbarrett mb;
  95   int ok = 1;
  96
  97   j = 1;
  98   for (i = 0; i < n; i++) {
  99     f[i].base = *(mp **)v[j++].buf;
 100     f[i].exp = *(mp **)v[j++].buf;
 101   }
 102
 103   rr = *(mp **)v[j].buf;
 104   mpbarrett_create(&mb, m);
 105   r = mpbarrett_mexp(&mb, MP_NEW, f, n);
 106   if (!MP_EQ(r, rr)) {
 107     fputs("\n*** mexp failed\n", stderr);
 108     fputs("m = ", stderr); mp_writefile(m, stderr, 10);
 109     for (i = 0; i < n; i++) {
 110       fprintf(stderr, "\ng_%u = ", i);
 111       mp_writefile(f[i].base, stderr, 10);
 112       fprintf(stderr, "\ne_%u = ", i);
 113       mp_writefile(f[i].exp, stderr, 10);
 114     }
 115     fputs("\nr = ", stderr); mp_writefile(r, stderr, 10);
 116     fputs("\nR = ", stderr); mp_writefile(rr, stderr, 10);
 117     fputc('\n', stderr);
 118     ok = 0;
 119   }
 120
 121   for (i = 0; i < n; i++) {
 122     MP_DROP(f[i].base);
 123     MP_DROP(f[i].exp);
 124   }
 125   MP_DROP(m);
 126   MP_DROP(r);
 127   MP_DROP(rr);
 128   mpbarrett_destroy(&mb);
 129   assert(mparena_count(MPARENA_GLOBAL) == 0);
 130   return (ok);
 131 }
 132
 133 static int t1(dstr *v) { return verify(1, v); }
 134 static int t2(dstr *v) { return verify(2, v); }
 135 static int t3(dstr *v) { return verify(3, v); }
 136 static int t4(dstr *v) { return verify(4, v); }
 137 static int t5(dstr *v) { return verify(5, v); }
 138
 139 static test_chunk tests[] = {
 140   { "mexp-1", t1, { &type_mp,
 141                     &type_mp, &type_mp,
 142                     &type_mp, 0 } },
 143   { "mexp-2", t2, { &type_mp,
 144                     &type_mp, &type_mp,
 145                     &type_mp, &type_mp,
 146                     &type_mp, 0 } },
 147   { "mexp-3", t3, { &type_mp,
 148                     &type_mp, &type_mp,
 149                     &type_mp, &type_mp,
 150                     &type_mp, &type_mp,
 151                     &type_mp, 0 } },
 152   { "mexp-4", t4, { &type_mp,
 153                     &type_mp, &type_mp,
 154                     &type_mp, &type_mp,
 155                     &type_mp, &type_mp,
 156                     &type_mp, &type_mp,
 157                     &type_mp, 0 } },
 158   { "mexp-5", t5, { &type_mp,
 159                     &type_mp, &type_mp,
 160                     &type_mp, &type_mp,
 161                     &type_mp, &type_mp,
 162                     &type_mp, &type_mp,
 163                     &type_mp, &type_mp,
 164                     &type_mp, 0 } },
 165   { 0, 0, { 0 } }
 166 };
 167
 168 int main(int argc, char *argv[])
 169 {
 170   sub_init();
 171   test_run(argc, argv, tests, SRCDIR "/tests/mpbarrett");
 172   return (0);
 173 }
 174
 175 #endif
 176
 177 /*----- That's all, folks -------------------------------------------------*/